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`According to the present invention, an apparatus for forming a single-crystalline thin film of a prescribed
`material on a substrate having a single-crystalline structure comprises irradiation means for irradiating the
`substrate with gas beams of low energy levels causing no sputtering of the prescribed material from
`directions which are perpendicular to a plurality of densest crystal planes having different directions in the
`single-crystalline thin film to be formed, and attitude control means for controlling the attitude of the
`substrate for setting prescribed relations between directions of crystal axes of the substrate and directions
`of incidence of the beams.
`The apparatus according to the tenth aspect of the present invention comprises attitude control means,
`whereby it is possible to set prescribed relations between the crystal axes of the single-crystalline substrate
`10 and the directions of incidence of the gas beams by employing this apparatus. Thus, it is possible to
`epitaxially form a new single~crystalline thin film on a single-crystalline substrate at a temperature below the
`crystallization temperature.
`According to the present invention, an apparatus for forming a single-crystalline thin film of a prescribed
`material on a substrate comprises film forming means for forming an amorphous or polycrystalline thin film
`15 of the prescribed material on the substrate by supplying a reaction gas, irradiation means for irradiating the
`substrate with gas beams of low energy levels causing no sputtering of the prescribed material from
`directions which are perpendicular to a. plurality of densest crystal planes having different directions in the
`single-crystalline thin film to be formed, and substrate rotating means for rotating the substrate.
`The apparatus according to the present invention comprises substrate rotating means, whereby it is
`20 possible to facilitate formation of an amorphous or polycrystalline thin film by intermittently applying the
`beams while regularly supplying the reaction gas and rotating the substrate during application pauses.
`Thus, it is possible to form an amorphous or polycrystalline thin film having high homogeneity, whereby
`high homogeneity is also attained in a single-crystalline thin film which is obtained by converting the same.
`According to the present invention, an apparatus for forming a single-crystalline thin film of a prescribed
`25 material on a substrate comprises film forming means for forming an amorphous or polycrystalline thin film
`of the prescribed material on the substrate by supplying a reaction gas, and irradiation means for irradiating
`the substrate with gas beams of low energy levels causing no sputtering of the prescribed material from
`directions which are perpendicular to a plurality of densest crystal planes having different directions in the
`single-crystalline thin film to be formed. The film forming means has supply system rotating means for
`rotating an end portion of a supply path for supplying the substrate with the reaction gas with respect to the
`substrate.
`The apparatus according to the present invention comprises supply system rotating means, whereby it
`is possible to obtain a single-crystalline thin film having high homogeneity while regularly supplying the
`reaction gas and applying the beams with no intermittent application of the beams. Namely, it is possible to
`35 efficiently form a single-crystalline thin film having high homogeneity.
`·According to the present invention, an apparatus for forming a single-crystalline thin film of a prescribed
`material on a substrate comprises a plurality of irradiation means for irradiating the substrate with a plurality
`of gas beams of low energy levels causing no sputtering of the prescribed material from directions which
`are perpendicular to a plurality of densest crystal planes having different directions in the single-crystalline
`thin film to be formed respectively, and control means for independently controlling operating conditions in
`the plurality of irradiation means respectively.
`In the apparatus according to the present invention, control means independently controls operating
`conditions in irradiation means such as output beam densities, for example, whereby states of a plurality of
`beams which are applied to the substrate are optimumly controlled. Thus, it is possible to efficiently form a
`45 high-quality single-crystalline thin film.
`The irradiation means preferably comprises an electron cyclotron resonance type ion source, and the
`gas beams are supplied by the ion source.
`According to the present invention, an apparatus for forming a single-crystalline thin film of a prescribed
`material on a substrate comprises irradiation means for irradiating the substrate with beams of a gas
`50 supplied by an ion source at low energy levels causing no sputtering of the prescribed material from
`directions which are perpendicular to a plurality of densest crystal planes having different directions in the
`single-crystalline thin film to be formed, and bias means for applying a bias voltage across the ion source
`and the substrate in a direction for accelerating ions.
`In the apparatus according to the present invention, bias means applies a bias voltage across the ion
`source and the substrate, whereby the gas beams are improved in directivity. Thus, it is possible to form a
`high-quality single-crystalline thin film having high homogeneity of the crystal orientation.
`According to the present invention, an apparatus for forming a single-crystalline thin film of a prescribed
`material on a substrate comprises irradiation means for irradiating the substrate with beams of a gas
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`supplied by an ion source at low energy levels causing no sputtering of the prescribed material from
`directions which are perpendicular to a plurality of densest crystal planes having different directions in the
`single-crystalline thin film to be formed, with a grid which is provided in the vicinity of an ion outlet of the
`ion source, and grid voltage applying means for applying a voltage to the grid for controlling conditions for
`extracting ions from the ion source.
`In the apparatus according to the present invention, grid voltage applying means optimumly controls
`conditions for extracting ions from the ion source, whereby it is possible to efficiently form a high-quality
`single-crystalline thin film.
`In the apparatus according to the present invention, the beam source is preferably an electron cyclotron
`resonance type ion source.
`In the apparatus according to the present invention, the gas beams are supplied by an electron
`cyclotron resonance type ion source, whereby the ion beams are excellent in directivity while it is possible
`to obtain strong neutral beams having excellent directivity at positions beyond a prescribed distance from
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`the ion source without employing means for neutralizing ions.
`According to the present invention, a beam irradiator for irradiating a target surface of a sample with a
`gas beam comprises a container for storing the sample, and a beam source for irradiating the target surface
`of the sample which is set in a prescribed position of the container with the gas beam, and at least a
`surface of a portion irradiated with the beam is made of a material having tt:ireshold energy which is higher
`than energy of the beam in sputtering by irradiation with the beam among an inner wall of the container and
`20 a member which is stored in the container.
`At least the surface of the portion irradiated with the beam is made of a material having threshold
`energy which is higher than energy of the beam in sputtering by the irradiation with the beam among the
`inner wall of the container and the member stored in the container, whereby no sputtering is caused even if
`the beam reaches the member. Therefore, consumption of the member by sputtering is suppressed, while
`25 contamination of the target sample with the material element forming the member is prevented.
`According to the present invention, a beam irradiator for irradiating a target surface of a sample with a
`gas beam comprises a container for storing the sample, and a beam source for irradiating the target surface
`of the sample which is set in a prescribed position of the container with the gas beam, and at least a
`surface of a portion irradiated with the beam is made of a material having threshold energy with respect to
`30 sputtering which is higher than that in the target surface of the sample among an inner wall of the container
`and a member which is stored in the container.
`At least the surface of the portion irradiated. with the beam is made of a material having threshold
`energy with respect to sputtering which is higher than that in the target surface of the sample among the
`inner wall of the container and the member stored in the container, whereby no sputtering is caused in this
`35 member when the target surface of the sample is irradiated with the beam causing no sputtering. Therefore,
`consumption of the member by sputtering is suppressed under such usage, while contamination of the
`target sample with the material element forming the member is prevented.
`According to the present invention, a beam irradiator for irradiating a target surface of a sample with a
`gas beam comprises a container for storing the sample, and a beam source for irradiating the target surface
`40 of the sample which is set in a prescribed position of the container with the gas beam, and at least a
`surface of a portion irradiated with the beam is made of a material containing an element which is larger in
`atomic weight than that forming the gas among an inner wall of the container and a member which is stored
`in the container.
`At least the surface of the portion irradiated with the beam is made of a material containing an element
`45 which is larger in atomic weight than that forming the beam gas among the inner wall of the container and
`the member stored in the container, whereby permeation of a different element in the member is
`suppressed. Therefore, deterioration of the member caused by invasion of the different element is
`suppressed.
`According to the present invention, a beam irradiator for irradiating a target surface of a sample with a
`50 gas beam comprises a container for storing the sample, and a beam source for irradiating the target surface
`of the sample which is set in a prescribed position of the container with the gas beam, and at least a
`surface of a portion irradiated with the beam is made of the same material as that forming the target surface
`of the sample among an inner wall of the container and a member which is stored in the container.
`At least the surface of the portion irradiated with the beam is made of the same material as that forming
`the target surface of the sample among the inner wall of the container and the member stored in the
`container, whereby the target sample is not contaminated with the material element forming the member
`even if sputtering is caused in this member.
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`The member stored in the container preferably includes reflecting means which is interposed in a path
`of the beam for separating the beam into a plurality of components and irradiating the target surface of the
`sample with the plurality of components from directions which are different from each other.
`The reflecting means is stored in the container and at least the surface of the portion irradiated with the
`s beam is made of a material causing no sputtering, the same material as that of the target surface of the
`sample, or a material containing an element which is larger in atomic weight than that forming the beam
`gas, whereby contamination of the sample by sputtering of the reflecting means is prevented or deteriora(cid:173)
`tion of the reflecting means is suppressed.
`The present invention is also directed to a beam irradiating method. According to the present invention,
`10 a beam irradiating method of irradiating a target surface of a sample with a gas beam comprises a step of
`setting the sample in a prescribed position of a container, and a step of irradiating the target surface of the
`sample which is set in the container with the gas beam, and the target surface is irradiated with the beam at
`energy which is lower than threshold energy of sputtering in a surface of a portion which is irradiated with
`the beam among an inner wall of the container and a member stored in the container.
`The target surface is irradiated with the beam at energy which· is lower than threshold energy of
`sputtering on the surface of the portion irradiated with the beam among the inner wall of the container and
`the member stored in the container, whereby no sputtering is· caused even if the beam reaches the
`member. Therefore, consumption of the member by sputtering is suppressed, while contamination of the
`target sample with the material element forming the member is prevented.
`The present invention is also directed to a method of forming single-crystalline thin film. According to
`the present invention, a method of forming a single-crystalline thin film of a prescribed material on a
`substrate comprises a step of depositing the prescribed material on the substrate under a low temperature
`causing no crystallization of the prescribed material and irradiating the prescribed material as deposited
`with a gas beam of low energy causing no sputtering of the prescribed material from one direction, thereby
`forming an axially oriented polycrystalline thin film of the material, and a step of irradiating the axially
`oriented polycrystalline thin film with gas beams of low energy causing no sputtering of the prescribed
`material under a high temperature below a crystallization temperature of the prescribed material from
`directions which are perpendicular to a plurality of densest crystal planes of different directions in the
`single-crystalline thin film, thereby converting the axially oriented polycrystalline thin film to a single-
`30 crystalline thin film.
`The axially oriented polycrystalline thin film is previously formed on the substrate and thereafter
`irradiated with the beams from a plurality of directions so that the thin film is converted to a single(cid:173)
`crystalline thin film. Therefore, even if the substrate is not uniformly irradiated with the beams from the
`plurality of directions due to a screen formed on the substrate, for example, at least either a single-
`35 crystalline thin film or an axially oriented polycrystalline thin film is formed on any portion on the substrate,
`whereby no remarkable deterioration of characteristics is caused.
`According to the ·present invention, a method of forming a single-crystalline thin film of a prescribed
`material on a substrate comprises a step of depositing the prescribed material on the substrate thereby
`forming a thin film of the material, a step of irradiating the thin film with a gas beam of low energy causing
`40 no sputtering of the prescribed material under a high temperature below a crystallization temperature of the
`prescribed material from one direction after the step, thereby converting the thin film to an axially oriented
`polycrystalline thin film, and a step of irradiating the axially oriented polycrystalline thin film with gas beams
`of low energy causing no sputtering of the prescribed material under a high temperature below the
`crystallization temperature of the prescribed material from directions which are perpendicular to a plurality
`45 of densest crystal planes of different directions in the single-crystalline thin film, thereby converting the
`axially oriented polycrystalline thin film to a single-crystalline thin film.
`The axially oriented polycrystalline thin film is previously formed on the substrate and thereafter
`irradiated with the beams from a plurality of directions, so that the thin film is converted to a single(cid:173)
`crystalline thin film. Therefore, even if the substrate is not uniformly irradiated with the beams from the
`so plurality of directions due to a screen formed on the substrate, for example. at least either a single.:
`crystalline thin film or an axially oriented polycrystalline thin film is formed on any portion on the substrate,
`whereby no remarkable deterioration of characteristics is caused.
`The direction of the gas beam in formation of the axially oriented polycrystalline thin film is preferably
`identical to one of the plurality of directions of the gas beams in the conversion of the axially oriented
`55 polycrystalline thin film to the single-crystalline thin film.
`The direction of application of the gas beam in formation of the axially oriented polycrystalline thin film
`is identical to one of the plurality of directions of gas beams for converting the axially oriented polycrystal(cid:173)
`line thin film to a single-crystalline thin film, whereby conversion to the single-crystalline thin film is
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`smoothly carried out.
`The gas is preferably an inert gas.
`The beam of an inert gas is so applied that no particularly remarkable influence is exerted on the
`electrophysical properties of the thin film even if the gas remains in the single-crystalline thin film as
`formed, while it is possible to easily remove the as-invaded gas from the thin film.
`The atomic weight of an element forming the inert gas is preferably lower than the maximum atomic
`weight among those of elements forming the prescribed material.
`The atomic weight of the element forming the inert gas is lower than the maximum atomic weight of
`elements forming the prescribed material which is grown as the thin film, whereby most part of atoms or
`ions of the applied inert gas are rearwardly scattered on the surface of the thin film or in the vicinity thereof,
`to hardly remain in the thin film.
`The prescribed material preferably contains an element forming a gas material which is a gas under a
`normal temperature, and the gas beam is preferably a beam of the gas material.
`The gas as applied contains an element forming the material grown as a thin film. Even if. atoms or ions
`15 of the element remain in the thin film after irradiation, therefore, these will not exert a bad influence on the
`single-crystalline thin film as impurities.
`The gas beam is preferably formed by an electron cyclotron resonance ion source.
`The beam generation source is an electron cyclotron resonance ion generation source. Therefore, the
`ion beam has high directivity, while a strong neutral beam can be obtained at a distance exceeding a
`20 prescribed length from the ion generation source without employing means for neutralizing ions. Further, it
`is possible to employ an electrically insulating substrate without employing means for neutralizing the ions.
`According to the present invention, a beam irradiator for irradiating a target surface of a sample with a
`gas beam comprises a single beam source for supplying the beam, and reflecting means for reflecting the
`beam which is supplied by the beam source, thereby enabling irradiation of the target surface with the gas
`in a plurality of prescribed directions of incidence, and the reflecting means comprises a reflector having a
`plurality of reflecting surfaces for reflecting the beam in a plurality of directions, and a screen which is
`interposed in a path of the beam between the beam source and the reflecting surfaces for selectively
`passing the beam thereby preventing multiple reflection by the plurality of reflecting surfaces.
`Multiple reflection of the beam by the plurality of reflecting surfaces is prevented by the screen,
`30 whereby no beam is applied from a direction other than a prescribed direction of incidence.
`The screen preferably further selectively passes the beam to uniformly irradiate the target surface with
`the beam.
`The target surface is uniformly irradiated with the beam by action of the screen. Therefore, a high
`quality single-crystalline thin film is formed when the apparatus is applied to formation of a single-crystalline
`thin film, for example.
`The present invention is also directed to a beam reflecting device. According to the present invention, a
`beam reflecting device for reflecting a gas beam which is supplied from a single beam source thereby
`enabling irradiation of a target surface of a sample with the gas in a plurality of prescribed directions of
`incidence comprises a reflector having a plurality of reflecting surfaces for reflecting the beam in a plurality
`40 of directions, and a screen which is interposed in a path of the beam between the beam source and the
`reflecting surfaces for selectively passing the beam thereby preventing multiple reflection by the plurality of
`reflecting surfaces.
`Multiple reflection of the beam by the plurality of reflecting surfaces is prevented by the screen,
`whereby no beam is applied from a direction other than a prescribed direction of incidence.
`The screen preferably further selectively passes the beam to uniformly irradiate the target surface with
`the beam.
`The target surface is uniformly irradiated with the beam by action of the screen. Therefore, a high(cid:173)
`quality single-crystalline thin film is formed when the apparatus is applied to formation of a single-crystalline
`thin film, for example.
`According to the present invention, a beam irradiator for irradiating a target surface of a sample with a
`gas beam comprises a single beam source for supplying the beam, and reflecting means for reflecting the
`beam which is supplied by the beam source, thereby enabling irradiation of the target surface with the gas
`in a plurality of prescribed directions of incidence, and the reflecting means comprises a first reflector which
`is arranged in a path of the beam. supplied from the beam source for reflecting the beam in a plurality of
`55 directions thereby generating a plurality of divergent beams having beam sections which are two(cid:173)
`dimensionally enlarged with progress of the beams, and a second reflector having a concave reflecting
`surface for further reflecting the plurality of divergent beams to be incident upon the target surface
`substantially as parallel beams from a plurality of directions.
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`The gas beams applied to the target surface of the sample are obtained by the single beam source and
`the reflecting means provided in the path, whereby it is possible to irradiate the target surface with gas
`beams from a plurality of different prescribed directions with no requirement for a plurality of beain sources.
`Further, the beam is reflected by the first reflector to be two-dimensionally diverged in a plurality of
`directions and then converted .to substantially parallel beams by the second reflector, whereby the beam
`· can be uniformly applied to the target surface which is wider than the section of the beam supplied from the
`beam source. Therefore, it is possible to widely and efficiently form a single-crystalline thin film of a
`prescribed material on a wide substrate provided with a thin film of the prescribed material on its surface or
`a wide substrate· having a thin film of the prescribed material being grown on its surface without scanning
`the substrate, by irradiating the substrate with a gas beam by this apparatus.
`The reflecting means preferably further comprises rectifying means which is provided in a path of the
`beams between the first reflector and the substrate for regularizing directions of the beams.
`The rectifying means is arranged in the path of the beam between the first reflector and the sample,
`whereby the beam can be regulated along a prescribed direction. Therefore, no strict accuracy is required
`tor the shapes and arrangement of the respective reflectors, whereby the apparatus can be easily
`structured.
`The reflecting means preferably further comprises beam distribution adjusting means which is inter(cid:173)
`posed in a path of the beam between the beam source and the first reflector for adjusting distribution of the
`beam on a section which is perpendicular to the path, thereby adjusting the amounts of respective beam
`20 components reflected by the first reflector in the plurality of directions.
`The beam distribution adjusting means adjusts the amounts of a plurality of beam components reflected
`by the first reflector, whereby the amounts of a plurality of beam components which are incident upon the
`target surface from a plurality of directions can be adjusted. Therefore, the amounts of the respective beam
`components incident upon the substrate can be optimumly set to be identical to each other, for example,
`25 whereby it is possible to efficiently form a high-quality single-crystalline thin film.
`According to the present invention, a beam reflecting device for reflecting a gas beam which is supplied
`from a single beam source thereby enabling irradiation of a target surface of a sample with the gas in a
`plurality of prescribed directions of incidence comprises a first reflector for reflecting the beam in a plurality
`of directions thereby generating a plurality of divergent beams having beam sections which are two-
`30 dimensionally enlarged with progress of the beams, and a second reflector having a concave reflecting
`surface for further reflecting the plurality of divergent beams to be incident upon the target surface
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`substantially as parallel beams from a plurality of directions.
`The gas beam which is supplied from the single beam source is reflected by the first reflector to be
`two-dimensionally diverged in a plurality of directions and then converted to substantially parallel beams by
`the second reflector, whereby it is possible to irradiate the target surface which is wider than the section of
`the beam supplied from the beam source from a plurality of directions with no requirement for a plurality of
`beam sources. Therefore, it is possible to widely and efficiently form a single-crystalline thin film of a
`prescribed material on a wide substrate provided with a thin film of the prescribed material on its surface or
`a wide substrate having a thin film of the prescribed material being grown on its surface without scanning
`the substrate, by irradiating the substrate with a gas beam by this apparatus.
`According to the present invention, a beam irradiator for irradiating a target surface of a sample with
`gas beams comprises a plurality of beam sources for supplying the gas beams, and a plurality of reflecting
`means for reflecting the beams which are supplied by the plurality of beam sources thereby enabling
`irradiation of a common region of the target surface with the gas in a plurality of prescribed directions of
`incidence, and each reflecting means comprises a first reflector which is arranged in a path of each beam
`supplied from each beam source for reflecting the beam thereby generating a beam having a beam section
`which is two-dimensionally enlarged with progress of the beam, and a second reflector having a concave
`reflecting surface for further reflecting the divergent beam to be incident upon a linear or strip-shaped
`common region of the target surface substantially as a parallel beam, while the beam irradiator further
`50 comprises moving means for scanning the sample in a direction intersecting with the linear or strip-shaped
`common region.
`The beams are reflected by the first reflector to be substantially one-dimensionally diverged and
`thereafter converted to substantially parallel beams by the second reflector, whereby it is possible to
`irradiate a linear or strip-shaped region which is wider than the beams supplied from the beam sources with
`55 parallel beams from prescribed directions of incidence. Further, the sample is scanned in a direction
`intersecting with the linear or strip-shaped region, whereby the beams can be uniformly applied to a wide
`target surface. In addition, a plurality of beam sources and a plurality of reflecting means are so provided
`that a wide target surface can be uniformly irradiated with beams from a plurality of directions of incidence.
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`Each reflecting means preferably further comprises rectifying means which is provided in a path of
`each beam between the first reflector and the substrate for regulating the direction of the beam.
`The rectifying means is arranged in the beam path between the first reflector and the substrate,
`whereby the beams can be regulated in a prescribed direction. Therefore, no strict accuracy is required for
`the shapes and arrangement of the respective reflectors, whereby the apparatus can be easily structured.
`According to the present invention, a beam reflecting device for reflecting a gas beam which is supplied
`from a beam source thereby enabling irradiation of a target surface of a sample with the gas in a prescribed
`direction of incidence comprises a first reflector for reflecting the beam thereby generating a divergent
`beam having a beam section which is two-dimensionally enlarged with progress of the beam, and a second
`reflector having a concave reflecting surface for further reflecting the divergent beam to be incident upon a
`linear or strip-shaped region of the target surface substantially as a parallel beam.
`The beams are reflected by the first reflector to be substantially one-dimensionally diverged and
`thereafter converted to substantially parallel beams by the second reflector, whereby it is possible to
`irradiate a linear or strip-shaped region which is wider than the beams supplied from the beam sources with
`the beams.
`Accordingly, an object of the present invention is to provide a technique which can form an axially
`oriented polycrystalline thin film oriented in a desired direction and a single-crystalline thin film having a
`desired crystal orientation on an arbitrary substrate including a single-crystalline substrate.
`Another object of the present invention is to provide a beam irradiator and a beam reflecting device for
`20 enabling efficient formation of a single-crystalline thin film.
`Throughout the specification, the term "substrate" is not restricted to a substance simply serving as a
`base to be provided thereon with a thin film, but generally indicates a medium to be provided thereon with a
`thin film, including a device having a prescribed function, for example.
`Throughout the specification, the term "gas beam" is a concept including all of a beam-type ion
`25 current, an atom current and a molecular flow.
`The foregoing and other objects, features, aspects and advantages of the present invention will become
`more apparent from the following detailed description of the present invention when taken in conjunction
`with the accompanying drawings.
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`30 BRIEF DESCRIPTION OF THE DRAWINGS
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`Fig. 1 is a model diagram showing an apparatus which is suitable for carrying out a method according to
`a first preferred embodiment of the present invention;
`Figs. 2A to 2C are perspective views showing a structure of a collimator;
`Figs. 3A and 38 are sectional views showing a sample;
`Fig. 4 is a front sectional view showing an apparatus which is suitable for carrying out a method
`according to a second preferred embodiment of the present invention;
`Fig. 5 is a perspective view showing a reflector which is employed in the method according to the
`second preferred embodiment of the present invention;
`· Figs. BA, BB and BC are a plan view, a side elevational view and a front elevational view showing an
`example of the reflector which is employed in the method according to the second preferred embodi·
`ment of the present invention;
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`Fig. 7 is a graph showing characteristics of an ECR ion generator which is employed in the method
`according to the second preferred embodiment of the present invention;
`Fig. 8 illustrates experimental data verifying