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`Samsung Electronics Co., Ltd. v. Demaray LLC
`Samsung Electronic's Exhibit 1022
`Exhibit 1022, Page 1
`
`

`

`
`
`US 6,911,351 132
`
`
`Page 2
`
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`Mori et al.
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`
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`
`4/2000
`
`
`6,046,465
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`
`Wang et al.
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`
`
`
`6,153,010
`
`
`................ 117/95
`Kiyoku et al.
`Sasanuma et al.
`6/2001
`6,252,894
`
`
`
`
`Tsuda et al.
`1/2002
`6,335,546
`
`
`
`
`Kneissl et 81.
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`6,448,102
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`
`
`
`8/2003
`.................. 257/76
`Davis et al.
`6,608,327
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`
`
`
`
`7/2004
`
`
`
`6,764,932
`
`
`................. 439/589
`Kong et al.
`Takeuchi et al.
`2001/0010372
`8/2001
`
`
`
`
`Althaus et al.
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`
`
`
`
`FOREIGN PATENT DOCUMENTS
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`
`62282474 A
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`
`
`02214182 A
`2/1989
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`
`11068256 A
`8/1997
`
`
`11251631
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`
`
`11312825
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`
`
`
`A *
`
`
`A1
`
`JP
`JP
`JP
`JP
`JP
`
`
`
`
`
`
`
`
`
`
`
`
`
`JP
`JP
`
`
`
`
`
`
`
`
`
`2002-518826
`2000—106455
`
`12/1999
`4/2000
`
`
`
`
`
`OTHER PUBLICATIONS
`
`
`
`
`
`
`
`
`
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`I. Kim et al., “Crystal tilting in GaN grown by pendeopitaxy
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`method on sapphire substrate”, Applied Physics Letters, VOl.
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`75, N0. 26, pp. 4109—4111, Dec. 27, 1999.
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`A. Sakai, “Transmission electron microscopy of defects in
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`GaN films formed by epitaxial lateral overgrowth”, Applied
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`Physics Letters, VOl. 73, N0. 4, pp. 481—483, Jul. 27, 1998.
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`H. Sone et al., “Optical and Crystalline Properties of Epi-
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`Hydride Vapor Phase Epitaxy”, Jpn. J. Appl. Phys. VOl. 38
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`
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`(1999), Part 2, N0. 4A, pp. L356—L359, Apr. 1, 1999.
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`
`Tsvetanka et al., “Pendeo—Epitaxy: A new Approach for
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`Lateral growth of Gallium Nitride Films”, Journal of Elec-
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`
`tronic Materials, VOl. 28, N0. 4., L5—L8, Apr. 1999.
`
`
`
`* cited by examiner
`
`
`
`
`
`
`
`Ex. 1022, Page 2
`
`Ex. 1022, Page 2
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`

`

`
`US. Patent
`
`
`
`
`
`Jun. 28, 2005
`
`
`
`
`
`Sheet 1 0f 43
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`US 6,911,351 132
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`
`H.0:
`
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`
`
`Ex. 1022, Page 3
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`

`

`
`US. Patent
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`
`Jun. 28, 2005
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`Sheet 2 0f 43
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`US 6,911,351 B2
`
`
`FIG. 2 (a)
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`
`40 12a 40 12b
`
`
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`
`12b
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`
`
`40
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`
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` 11
`
`Ex. 1022, Page 4
`
`Ex. 1022, Page 4
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`

`

`
`US. Patent
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`Jun. 28, 2005
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`Sheet 3 0f 43
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`US 6,911,351 B2
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`12b
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`12b
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`
`Ex. 1022, Page 5
`
`Ex. 1022, Page 5
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`

`

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`US. Patent
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`Jun. 28, 2005
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`Sheet 4 0f 43
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`US 6,911,351 132
`
`w.0:
`
`m2.3ma7m:Sonm:I9ONa
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`
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`
`
`NHma
`
`:
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`
`
`Ex. 1022, Page 6
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`

`

`
`US. Patent
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`Jun. 28, 2005
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`Sheet 5 0f 43
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`US 6,911,351 B2
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`FIG. 5
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`Ex. 1022, Page 7
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`Ex. 1022, Page 7
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`US. Patent
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`Jun. 28, 2005
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`Sheet 6 0f 43
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`US 6,911,351 B2
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`FIG. 6 (d)
`
`14a
`
`14a
`
`
`
` 14
`
`
`‘ \‘13.............
`13
`
`
`
`131';23333333335.5111:2313?1321135533133931:35:i:
`12
`
`
`11
`
`
`
`
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`
`
`Ex.1022,Page8
`
`Ex. 1022, Page 8
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`

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`US. Patent
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`Jun. 28, 2005
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`Sheet 7 0f 43
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`US 6,911,351 B2
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`
`FIG. 7
`
`
`
`
`
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`
`
`MASK OF METAL WITH HIGH MELTING POINT
`
`
`
`(ARB.UNITS)
`EL~INTENSITY
`
`
`MASK OF DIELECTRIC
`
`
`
`
`
`ROOM TEMPERATURE
`
`EXCTTATION WAVELENGTH=325nm
`
`
`
`300
`
`
`
`350
`
`
`
`400
`
`
`
`
`
`450
`
`
`
`500
`
`WAVELENGTH (nm)
`
`550
`
`
`
`600
`
`
`
`650
`
`
`
`
`
`Ex. 1022, Page 9
`
`Ex. 1022, Page 9
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`

`
`US. Patent
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`Jun. 28 2005
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`Sheet 8 0f 43
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`US 6,911,351 B2
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`FIG.8
`
`11111111111111
`
`Ex. 1022, Page 10
`
`

`

`
`US. Patent
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`Jun. 28, 2005
`
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`Sheet 9 0143
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`US 6,911,351 132
`
`A m
`
`
`
`zfimsm:n:m:o:o:,wea:E
`
`E
`
`
`
`«N
`
`m.0;
`
`<:-—_.!--
`
`
`.NV.iii“!null...rldanMWWmmwmw
`
`.Ii\lI.IIII:I-All4”.
`
`
`
`
`
`A
`
`Ex. 1022, Page 11
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`US. Patent
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`Jun. 28, 2005
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`Sheet 10 0f 43
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`US 6,911,351 B2
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`4011a 40 11b
`
`
`
`
`
`11b
`
`
`
`
`
`40
`
` 11A
`
`
`
`
`FIG.10(b)
`
`
`
`lla
`
`
`
`
`11b
`
`
`11b
`
`
`11b lla
`
`
`
`
`11A
`
`Ex. 1022, Page 12
`
`Ex. 1022, Page 12
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`

`

`
`US. Patent
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`Jun. 28, 2005
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`Sheet 11 0f 43
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`
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`US 6,911,351 132
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`S.0:
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`Ex. 1022, Page 13
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`Ex. 1022, Page 13
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`

`

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`US. Patent
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`Jun. 28 2005
`
`Sheet 12 0f 43
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` NH.0:
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`
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`Ex. 1022, Page 14
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`

`

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`US. Patent
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`Jun. 28, 2005
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`Sheet 13 0f 43
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`US 6,911,351 B2
`
`
`FIG. 13
`
`
`
`
`
`LIGHTINTENSITY(a.u.)
`
`I
`
`
`C53 CD
`
`I
`
`
`
`4:. O
`
`l
`
`
`
`DO 0
`
`O
`
`
`
`
`
`
`l\3 CD
`
`
`
`
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`“(:1 O
`
`
`
`0') 0
`
`Ex. 1022, Page 15
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`Ex. 1022, Page 15
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`

`

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`US. Patent
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`Jun. 28 2005
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`Sheet 14 0143
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`US 6,911,351 132
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`E.0:
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`Ex. 1022, Page 16
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`US. Patent
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`Jun. 28, 2005
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`Sheet 15 0f 43
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`US 6,911,351 B2
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`FIG. 15
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`LIGHTINTENSITY(8.11.)
`
`
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`
`
`
`
`INDEX
`
`—1
`
`
`
`0
`
`
`
`1
`
`
`
`2
`
`
`
`4
`3
`
`
`
`
`DISTANCE FROM ACTIVE LAYER (u m)
`
`
`
`5
`
`
`
`
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`
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`
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`
`
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`
`
`
`REFRACTIVE
`
`
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`
`
`Ex. 1022, Page 17
`
`Ex. 1022, Page 17
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`US. Patent
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`Jun. 28, 2005
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`Sheet 16 0f 43
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`US 6,911,351 B2
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`FIG. 16
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`
`
`LIGHTINTENSITY(a.u.)
`
`Ex. 1022, Page 18
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`Ex. 1022, Page 18
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`US. Patent
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`Jun. 28, 2005
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`Sheet 17 Of 43
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`US 6,911,351 B2
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`FIG. 17
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`14c 14b 14C 143
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`
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`
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`14a
`
`
`
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`
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`SURFACE PHOTOGRAPH
`
`
`(OPTICAL MICROSCOPE)
`
`
`
`'
`
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`
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`CROSS—SECTION
`
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`Ex.1022,Page19
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`Ex. 1022, Page 19
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`

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`US. Patent
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`Jun. 28 2005
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`US 6,911,351 132
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` m:d:
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`Ex. 1022, Page 20
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`Jun. 28, 2005
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`Sheet 19 0f 43
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`US 6,911,351 B2
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`PIG.19(a>
`
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`
`
`I
`
`EVAPORATION\
`
`
`STEP
`MOLECULE
`
`E’AOSORPTION
`
`,‘flim . ’l
`
`
`
`
`
`
`
`
`
`EVAPORATION
`EVAPORATION\
`.
`;.;.;.;.;.;.;
`
`camaxfizzzazzazzzzaruzz
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`.;.;.;.-_.;.;.;.:.;.3.;;.3.3.3.3.;:.;.3.;.:.;.;_;.;_;.;.;.;
`
`
`
`
`
`
`
`w
`12
`
`11
`
`
`
`
`
`
`E3ABSORPTION
`
`
`EVAPORATION\
`a
`
`
`
`
`
`
`DIFFUSION /EVAPORATION
`
`
`'I/I/I/l/ll/l/l/I/I/I/M 403
`.
`
`-:?:3:?:1:3:3:1:3:3:3:3:3:?:3:3:izi:3:f:f:{:{:{:{:f:{:i_:f:f_:f:i:
`402
`
`
`FIG.19(b)
`
`
`
`MOLECULE
`
`STEP
`
`
`
`
`
`
`
`
`
`ABSORPTION
`
`404'
`
`
`
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`
`
`
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`401
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`
`
`Ex. 1022, Page 21
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`Ex. 1022, Page 21
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`US. Patent
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`Jun. 28, 2005
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`Sheet 20 0f 43
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`US 6,911,351 B2
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`FIG.20(a>
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`
`14C
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`
`
`14A
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`
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`Ex. 1022, Page 22
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`Ex. 1022, Page 22
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`US. Patent
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`Jun. 28, 2005
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`Sheet 21 0f 43
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`US 6,911,351 B2
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`FIG.21(a)
`
`
`
`
`FIG.21(b>
`
`
`FIG.21(c>
`
`
`
`FIG. 21(d)
`
`
`
`
`14B
`
`
`
`
`
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`
`
`14c
`‘ “
`EEB’QEagéyIE;:::'
`.
`13
`
`“#:2231233?
`12
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`Ex. 1022, Page 23
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`Ex. 1022, Page 26
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`Ex. 1022, Page 26
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`Sheet 25 0f 43
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`US 6,911,351 132
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`Ex. 1022, Page 27
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`US 6,911,351 132
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`Ex.1022,Page28
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`Ex. 1022, Page 28
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`Ex. 1022, Page 29
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`Sheet 28 0f 43
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`FIG.28(a)
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`Ex.1022,Page30
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`Sheet 29 0f 43
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`FIG.29(a)
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`FIG.29(b)
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`Ex. 1022, Page 32
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`Sheet 34 0f 43
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`US 6,911,351 132
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`Ex. 1022, Page 36
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`Sheet 36 0f 43
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`FIG. 36 (a)
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`Ex. 1022, Page 38
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`Ex. 1022, Page 38
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`Sheet 37 0f 43
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`US 6,911,351 B2
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`FIG. 37
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`PRIOR ART
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`Ex. 1022, Page 39
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`Ex. 1022, Page 39
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`US 6,911,351 B2
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`Ex. 1022, Page 40
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`Sheet 39 0f 43
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`US 6,911,351 132
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`Ex. 1022, Page 41
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`Ex. 1022, Page 41
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`Sheet 40 0f 43
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`US 6,911,351 B2
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`FIG.40(a)
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`Ex. 1022, Page 42
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`FIG. 41
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`PRIOR ART
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`LIGHTINTENSITY(a.u.)
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`INDEX
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`DISTANCE FROM ACTIVE LAYER (11m)
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`REFRACTIVE
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`Ex. 1022, Page 43
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`Ex. 1022, Page 43
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`Sheet 42 0f 43
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`FIG. 42
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`PRIOR ART
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`INTENSITY(a.u.)
`LIGHT
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`Ex. 1022, Page 44
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`Ex. 1022, Page 44
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`Sheet 43 0f 43
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`FIG. 43
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`PRIOR ART
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`(M PLANE)
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`Ex. 1022, Page 45
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`Ex. 1022, Page 45
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`US 6,911,351 B2
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`2
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`opening is formed over a portion of the insulating film 310
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`above the ridge. Also, on a portion of the n-type contact
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`layer 303 not covered with the insulating film 310, an n-side
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`electrode 312 in ohmic contact with the n-type contact layer
`303 is formed.
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`In the semiconductor laser diode having the aforemen-
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`tioned structure, when a predetermined voltage is applied to
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`the p-side electrode 311 with the n-side electrode 312
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`grounded, optical gain is generated within the MQW active
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`layer 306, so as to show laser action at a wavelength of
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`approximately 400 nm.
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`The wavelength of laser action depends upon the com-
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`position ratios x and y or the thicknesses of the Ga1_xIan
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`and Ga1_yInyN layers included in the MQW active layer 306.
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`At present, the laser diode having this structure has been
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`developed to show continuous laser action at room tempera-
`ture or more.
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`Furthermore, laser action in the fundamental mode of the
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`lateral mode along a horizontal direction (parallel to the
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`substrate surface) can be shown by adjusting the width or
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`height of the ridge. Specifically,
`the laser action of the
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`fundamental lateral mode can be shown by providing a
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`difference in the light confinement coefficient between the
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`fundamental lateral mode and a primary or higher mode.
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`The substrate 301 is formed from, apart from sapphire,
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`silicon carbide (SiC), neodymium gallate (NdGaO3) or the
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`like, and any of these materials cannot attain lattice match
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`with gallium nitride and is difficult to attain coherent growth.
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`As a result, any of these materials includes a large number
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`of mixed dislocations, namely, mixed presence of edge
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`dislocations, screw dislocations and other dislocations. For
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`example, when the substrate is made from sapphire, the
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`substrate includes dislocations at a density of approximately
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`1><109 cm'z, which degrades the reliability of the semicon-
`ductor laser diode.
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`As a method for reducing the density of dislocations,
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`epitaxial
`lateral overgrowth (ELOG) has been proposed.
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`This is an effective method for reducing threading disloca-
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`tions in a semiconductor crystal with large lattice mismatch.
`CONVENTIONAL EXAMPLE 2
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`1
`METHOD OF FABRICATING NITRIDE
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`SEMICONDUCTOR, METHOD OF
`FABRICATING NITRIDE SEMICONDUCTOR
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`DEVICE, NITRIDE SEMICONDUCTOR
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`DEVICE, SEMICONDUCTOR LIGHT
`EMITTING DEVICE AND METHOD OF
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`FABRICATING THE SAME
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`CROSS-REFERENCED TO RELATED
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`APPLICATIONS
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`This application is a Divisional of application Ser. No.
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`09/712,127 filed Nov. 15, 2000, now US. Pat. No. 6,720,
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`586 issued Apr. 13, 2004.
`BACKGROUND OF THE INVENTION
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`The present invention relates to a method of fabricating a
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`nitride semiconductor for use in a short-wavelength semi-
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`conductor laser diode and the like expected to be applied to
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`the fields of optical information processing and the like, a
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`semiconductor device and a semiconductor light emitting
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`device using the nitride semiconductor and a method of
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`fabricating the same.
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`Recently, a nitride semiconductor of a group III—V
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`compound, that is, a group V element including nitride (N),
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`is regarded as a promising material for a short-wavelength
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`light emitting device due to its large energy gap.
`In
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`particular, a gallium nitride-based compound semiconductor
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`(AleayInZN, wherein 0éx, y, z§1 and X+y+z=1) has been
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`earnestly studied and developed, resulting in realizing a
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`practical blue or green light emitting diode (LED) device.
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`Furthermore, in accordance with capacity increase of an
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`optical disk unit, a semiconductor laser diode lasing at
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`approximately 400 nm is earnestly desired, and a semicon-
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`ductor laser diode using a gallium nitride-based semicon-
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`ductor is to be practically used.
`CONVENTIONAL EXAMPLE 1
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`Now, a gallium nitride-based semiconductor laser diode
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`according to Conventional Example 1 will be described with
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`reference to drawings.
`FIG. 37 shows the sectional structure of the conventional
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`gallium nitride-based semiconductor laser diode showing
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`laser action. As is shown in FIG. 37,
`the conventional
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`semiconductor laser diode includes a buffer layer 302 of
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`GaN, an n-type cladding layer 304 of n-type aluminum
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`gallium nitride (AlGaN), an n-type light guiding layer 305
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`of n-type GaN, a multiple quantum well (MQW) active layer
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`306 including gallium indium nitride layers having different
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`wherein 0<y<x<1), a p-type light guiding layer 307 of
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`p-type GaN, a p-type cladding layer 308 of p-type AlGaN
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`and a p-type contact layer 309 of p-type GaN successively
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`formed on a substrate 301 of sapphire by, for example, metal
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`organic vapor phase epitaxial growth (MOVPE).
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`An upper portion of the p-type cladding layer 308 and the
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`p-type contact layer 309 is formed into a ridge with a width
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`of approximately 3 through 10 pm. A lamination body
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`including the MQW active layer 306 is etched so as to
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`expose part of the n-type contact layer 303, and the upper
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`face and the side faces of the etched lamination body are
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`covered with an insulating film 310. In a portion of the
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`insulating film 310 above the p-type contact layer 309, a
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`stripe-shaped opening is formed, a p-side electrode 311 in
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`ohmic contact with the p-type contact layer 309 through the
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`FIG. 38 schematically shows the distribution of crystal
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`dislocations in a semiconductor layer of gallium nitride
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`The outline of the ELOG will be described with reference
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`to FIG. 38. First, a seed layer 402 of GaN is grown on a
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`substrate 401 of sapphire by the MOVPE or the like.
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`Next, a dielectric film of silicon oxide or the like is
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`deposited by chemical vapor deposition (CVD) or the like,
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`and the deposited dielectric film is formed into a mask film
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`403 having an opening pattern in the shape of stripes with a
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`predetermined cycle by photolithography and etching.
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`Then, a semiconductor layer 404 of GaN is formed on the
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`mask film 403 by selective growth with portions of the seed
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`layer 402 exposed from the mask film 403 used as a seed
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`crystal by the MOVPE or halide vapor phase epitaxial
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`growth.
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`At this point, although a dislocation high-density region
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`404a where the dislocation density is approximately 1><109
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`cm"2 is formed in a portion of the semiconductor layer 404
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`above the opening of the mask film 403, a dislocation
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`low-density region 404b where the dislocation density is
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`approximately 1><107 cm"2 can be formed in a portion of the
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`semiconductor layer 404 laterally grown on the mask film
`403.
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`Ex. 1022, Page 46
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`Ex. 1022, Page 46
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`

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`US 6,911,351 B2
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`3
`FIG. 39 shows the sectional structure of a semiconductor
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`laser diode whose active area, namely, a ridge working as a
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`current injecting region, is formed above the dislocation
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`low-density region 404b. In FIG. 39, like reference numerals
`are used to refer to like elements shown in FIGS. 37 and 38.
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`When the current injecting region is formed above the
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`dislocation low-density region 404b of the MQW active
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`layer 306 in this manner, the reliability of the laser diode can
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`be improved.
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`As a result of various examinations, the present inventors
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`have found that semiconductor laser diodes according to
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`Conventional Examples 1 and 2 have the following prob-
`lems:
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`First,
`the problems of the growth method of a nitride
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`semiconductor by the ELOG according to Conventional
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`Example 2 will be described.
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`FIGS. 40(a) through 40(d) schematically show a state
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`where polycrystals 405 of gallium nitride are deposited on
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`the mask film 403 during the growth of the semiconductor
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`layer 404 so as to degrade the crystallinity of the semicon-
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`ductor layer 404.
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`Specifically, the mask film 403 having the openings is first
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`formed on the seed layer 402 as is shown in FIG. 40(a), and
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`plural semiconductor layers 404 are respectively grown by
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`using, as the seed crystal, the portions of the seed layer 402
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`exposed in the openings of the mask film 403 as is shown in
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`FIG. 40(b). At this point, since the mask film 403 is formed
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`from a dielectric, plural polycrystals 405 that cannot be
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`crystallized on a dielectric may be deposited on the mask
`film 403.
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`Next, as is shown in FIGS. 40(6) and 4000, when the
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`plural semiconductor layers 404 are grown to be integrated
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`and to have a flat face with the polycrystals 405 deposited,
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`a region 404C with poor crystallinity is formed on each
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`polycrystal 405.
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`The present inventors have found that a laser diode with
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`good characteristics cannot be obtained when the current
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`injecting region is formed above the region 404C with poor
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`crystallinity.
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`Second, the present inventors have found a problem that,
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`in the semiconductor laser diode according to Conventional
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`Example 1 or 2, it is difficult to increase the light confine-
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`ment coefficient of the active layer along a direction vertical
`to the substrate surface.
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`FIG. 41 shows the relationship, in the semiconductor laser
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`diode of Conventional Example 1, between the distribution
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`of a refractive index of the MQW active layer 306 along the
`direction vertical to the substrate surface and the distribution
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`of light intensity on a cavity facet. It is understood that part
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`of generated light confined within the MQW active layer 306
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`leaks to the substrate 301 so as to generate a standing wave
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`in the n-type contact layer 303. When the generated light is
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`thus largely leaked from the MQW active layer 306 to the
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`substrate 301, the light confinement ratio in the MQW active
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`layer 306 is lowered, resulting in increasing the threshold
`value for laser action.
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`Also, FIG. 42 shows a far-field pattern of the laser diode
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`of Conventional Example 1. In this drawing, the abscissa
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`indicates a shift of emitted light from the normal direction of
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`the cavity facet toward the horizontal direction (along the
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`substrate surface), and the ordinate indicates light intensity
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`of the emitted light. When the generated light is largely
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`leaked to the substrate 301 as in Conventional Example 1, it
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`is also difficult to obtain a unimodal far-field pattern. This
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`goes for the semiconductor laser diode of Conventional
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`Example 2.
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`4
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`Thirdly, the semiconductor laser diode of Conventional
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`Example 1 has a problem that, in dividing plural laser diodes
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`formed on a wafer into individual
`laser chips by,
`for
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`example, cleavage, the facet of the cavity cannot be flat
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`because the substrate of sapphire and the nitride semicon-
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`ductor layer have different crystal planes. Specifically, as is
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`shown in FIG. 43, sapphire forming the substrate 301 is
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`easily cleaved on the (1—100) surface orientation, namely,
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`the so-called M plane, and hence, the substrate is generally
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`cleaved on the M plane of sapphire.
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`However,
`the M plane of a nitride semiconductor, for
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`example, gallium nitride is shifted from the M plane of
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`sapphire by 30 degrees in the plane, and hence, the M plane
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`of sapphire accords with the (11—20) surface orientation,
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`namely,
`the so-called A plane, of gallium nitride.
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`Accordingly, when the substrate 301 is cleaved, cleaved
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`ends of the buffer layer 302 and the lamination body above
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`are shifted from that of the substrate 301 by 30 degrees so
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`as to appear as an irregular face with level differences of
`several hundreds nm.
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`When the cavity facet is such an irregular face, mirror loss
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`of laser at the cavity facet is increased, so as to increase the
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`operation current of the semiconductor laser diode, which
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`can degrade the reliability of the semiconductor laser diode.
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`Furthermore, since the irregularities are randomly formed on
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`the cavity facet, it is difficult to form with good reproduc-
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`ibility a cavity facet having a predetermined reflectance,
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`which lowers the yield. Even when the cavity is formed not
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`by cleavage but by dry etching, the same problem arises.
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`Herein, a minus sign “—” used in a surface orientation
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`indicates inversion of an index following the minus sign.
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`On the other hand, in the semiconductor laser diode of
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`Conventional Example 2, the stripe-shaped opening of the
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`mask film 403 for the selective growth is formed parallel to
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`the M-axis of the semiconductor layer 404. This is because
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`a rate of the lateral growth along the A-axis is much higher
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`than in other directions, and hence, the selective growth can
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`be effectively proceeded in a short period of time. Therefore,
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`the dislocation low-density region 404b is parallel to the
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`M-axis, and therefore, the cavity facet of the laser diode
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`formed above the dislocation low-density region naturally
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`accords with the M plane. As a result, it is necessary to
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`cleave the substrate 401 on the Aplane. Although sapphire
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`can be easily cleaved on the M plane as described above, it
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`cannot be easily cleaved on the A plane, which largely
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`lowers the yield of the semiconductor laser diode.
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`Fourthly,
`it is known that an angle (tilt) between the
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`C-axis of the seed layer 402 and the C-axis of the semicon-
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`ductor layer 404 selectively grown above the seed layer 402
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`is approximately 0.1 through 1 degree in the ELOG.
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`On the other hand, when the ELOG is conducted again by
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`using the dislocation low-density region 404b obtained by
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`the ELOG as the seed crystal and covering the dislocation
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`high-density region 404a with another mask film for selec-
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`tive growth, a nitride semiconductor crystal can be obtained
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`merely from the dislocation low-density region 404b.
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`Accordingly, a cavity having a facet according to the Aplane
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`can be formed on the crystal formed from merely the
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`dislocation low-density region 404b, resulting in largely
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`increasing the yield in the cleavage.
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`When the cavity is formed along the A-axis, however, a
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`waveguide is formed in a Zigzag manner along the C-axis
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`because of the tilt of the C-axis between the seed layer 402
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`and the selectively grown layer above the seed layer 402 as
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`described above. Such a zigzag waveguide causes
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`waveguide loss, resulting in a problem of increase of the
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`Ex. 1022, Page 47
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`Ex. 1022, Page 47
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`

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`5
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`operation current of the laser diode. Moreover, in a vertical
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`cavity surface emitting laser diode array where plural cavi-
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`tys are arranged in a direction vertical
`to the substrate
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`surface, there arises a problem that the directions of emitting
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`laser beams from the respective cavitys in the array do not
`accord with one another.
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`Fifthly, in the semiconductor laser diode of Conventional
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`Example 2, the width of the dislocation low-density region
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`404b is as small as appro