Abstract: The contact resistance between an Ohmic electrode and an electron transit layer is reduced compared with a case in which the Ohmic electrode is provided to a depth less than the heterointerface. As a result, for an Ohmic electrode provided in a structure comprising an electron transit layer formed of a first semiconductor layer formed on a substrate, an electron supply layer comprising a second semiconductor layer forming a heterojunction with the electron transit layer and having a smaller electron affinity than the first semiconductor layer, and a two-dimensional electron layer induced in the electron transit layer in the vicinity of the heterointerface, the end portion of the Ohmic electrode is positioned in the electron transit layer in penetration into the electron supply layer at a depth equal to or greater than the heterointerface.

Abstract: The contact resistance between an Ohmic electrode and an electron transit layer is reduced compared with a case in which the Ohmic electrode is provided to a depth less than the heterointerface. As a result, for an Ohmic electrode provided in a structure comprising an electron transit layer formed of a first semiconductor layer formed on a substrate, an electron supply layer comprising a second semiconductor layer forming a heterojunction with the electron transit layer and having a smaller electron affinity than the first semiconductor layer, and a two-dimensional electron layer induced in the electron transit layer in the vicinity of the heterointerface, the end portion of the Ohmic electrode is positioned in the electron transit layer in penetration into the electron supply layer at a depth equal to or greater than the heterointerface.

Abstract: The contact resistance between an Ohmic electrode and an electron transit layer is reduced compared with a case in which the Ohmic electrode is provided to a depth less than the heterointerface. As a result, for an Ohmic electrode provided in a structure comprising an electron transit layer formed of a first semiconductor layer formed on a substrate, an electron supply layer comprising a second semiconductor layer forming a heterojunction with the electron transit layer and having a smaller electron affinity than the first semiconductor layer, and a two-dimensional electron layer induced in the electron transit layer in the vicinity of the heterointerface, the end portion of the Ohmic electrode is positioned in the electron transit layer in penetration into the electron supply layer at a depth equal to or greater than the heterointerface.

Abstract: An etching structure includes a substrate, a to be etched filmcovering the principal surface of the substrate, and an exposure region exposing the principal surface of the substrate and obtained by removing a part of the to be etched film. A region of the to be etched film constitutes a peripheral region surrounding the exposure region. Another region of the to be etched film outside the peripheral region constitutes a flat region. The film thickness of the to be etched film increases as the distance from the exposure region increases, such that the inclination of the outline of the cross section of the to be etched film that exists within the peripheral region decreases as the distance from the exposure region increases. The to be etched film has a side wall that extends perpendicularly to the principal surface at a boundary between the peripheral region and the flat region.

Abstract: There is provided an etching method in which a protective film existing in an etching-destined region of a substrate structure is removed by means of ICP-RIE to form an exposure region of the principal surface of the substrate. The substrate structure comprises a substrate, a protective film formed on the substrate, a photoresist layer formed on the protective film, and a hole formed throughout the photoresist layer. The hole comprises an opening formed in the photoresist layer surface and a hollow linked to the opening in the thickness direction of the photoresist layer and reaching the protective film. ICP-RIE is performed under conditions such that (1) ICP power is 20 to 100 W, (2) RIE power is 5 to 50 W, and (3) the pressure in the etching chamber is 1 to 100 mTorr.

Abstract: The contact resistance between an Ohmic electrode and an electron transit layer is reduced compared with a case in which the Ohmic electrode is provided to a depth less than the heterointerface. As a result, for an Ohmic electrode provided in a structure comprising an electron transit layer formed of a first semiconductor layer formed on a substrate, an electron supply layer comprising a second semiconductor layer forming a heterojunction with the electron transit layer and having a smaller electron affinity than the first semiconductor layer, and a two-dimensional electron layer induced in the electron transit layer in the vicinity of the heterointerface, the end portion of the Ohmic electrode is positioned in the electron transit layer in penetration into the electron supply layer at a depth equal to or greater than the heterointerface.

Abstract: There is provided an etching method in which a protective film existing in an etching-destined region of a substrate structure is removed by means of ICP-RIE to form an exposure region of the principal surface of the substrate. The substrate structure comprises a substrate, a protective film formed on the substrate, a photoresist layer formed on the protective film, and a hole formed throughout the photoresist layer. The hole comprises an opening formed in the photoresist layer surface and a hollow linked to the opening in the thickness direction of the photoresist layer and reaching the protective film. ICP-RIE is performed under conditions such that (1) ICP power is 20 to 100 W, (2) RIE power is 5 to 50 W, and (3) the pressure in the etching chamber is 1 to 100 mTorr.

Abstract: In a semiconductor fabrication process, a compound semiconductor layer including nitrogen is treated with nitrogen plasma to recover from nitrogen vacancies in its surface. For example, in the fabrication of a compound semiconductor transistor, a first compound semiconductor layer including nitrogen and a second compound semiconductor layer differing in composition from the first compound semiconductor layer are deposited, source and drain electrodes are formed on the second compound semiconductor layer, and part of the second compound semiconductor layer between the source and drain electrodes is removed by dry etching to expose the first compound semiconductor layer. The first compound semiconductor layer is annealed to remove adsorbed dry etching gas species; then its exposed surface is treated with nitrogen plasma to recover from nitrogen vacancies left by the dry etching and annealing processes.

Abstract: A polymer material containing a repetitive unit having a formula: The polymer material has a higher glass transition temperature and a lower water absorption than those of deuterated PMMA, but has a transparency equivalent with that of deuterated PMMA. The material also shows neither light absorption nor scattering in an operating wavelength region.

Abstract: A polymer pattern forming method including the steps of (a) generating radicals in a pattern forming region of a matrix layer which uniformly contains a radical generating agent, thereby forming a patterned latent image due to the radicals in the pattern forming region; and (b) bringing a monomer which polymerizes by radical polymerization into contact with the matrix layer in which the patterned latent image has been or is being formed, to have the radicals which have been or are being generated induce a chain addition polymerization of the monomer so as to form a polymer pattern on the pattern forming region.

Abstract: An optical waveguide having a clad and a core, the core being made of polymer material containing a repetitive unit having formula (1), (2) or (3): 1

Abstract: An optical waveguide having a clad and a core, the core being made of polymer material containing a repetitive unit having formula (1), (2) or (3): Each of these polymer materials has a higher glass transition temperature and lower water absorption than those of deuterated PMMA, has a transparency equivalent with that of deuterated PMMA, and shows neither light absorption nor scattering in the operating wavelength region. An optical waveguide with a core fabricated using these polymer materials is high in heat resistance and low in water absorption. Thus using the waveguide will successfully provide optical communication elements with an advanced durability against the environment.

Abstract: A diazonium salt for a color-forming layer of a thermosensitive recording medium, having formula (1): ##STR1## wherein R is an alkyl group having four carbon atoms which is selected from the group consisting of n-butyl, t-butyl, and sec-butyl, and X.sup.- is selected from the group consisting of hexafluorophosphate ion PF.sub.6.sup.-, tetrafluoroborate ion BF.sub.4.sup.- and tetraphenylborate ion (C.sub.6 H.sub.5).sub.4 B.sup.-. In a first embodiment, a thermosensitive recording medium has a color-forming layer which includes a diazonium salt as described above, a basic compound and a coupler. In a second embodiment, a thermosensitive recording medium has a color-forming layer which includes: a diazonium salt, a basic compound, and a coupler, wherein the diazonium salt has a formula (2): ##STR2## where R.sup.1 and R.sup.2 are alkyl groups each having one or more carbon atoms, and X.sup.- is selected from the group consisting of hexafluorophosphate ion PF.sub.6.sup.-, tetrafluoroborate ion BF.sub.4.sup.

Abstract: A process for forming a photoresist pattern comprises the steps of forming a photoresist layer on an underlying layer, forming a contrast enhancement layer for enhancing the contrast of light entering the photoresist layer on the photoresist layer, selectively exposing the photoresist layer through the contrast enhancement layer to light, and developing the photoresist layer to form a photoresist pattern. The contrast enhancement layer is formed as a layer containing a photobleachable agent and a material soluble in both of a nonpolar organic solvent and an aqueous alkali solution. The material is selected from the group of abietic acid, a derivative thereof, a rosin containing abietic acid as the main component, and a derivative thereof. The contrast enhancement layer is treated and removed simultaneously with development for the photoresist. The stability of a coating solution for the contrast enhancement layer is remarkably high.

Abstract: A photoconductor for electrophotography prepared by forming a carrier generation layer made from an organic photoconducting material on a conductive substrate and further forming a carrier transport layer on the carrier generation layer wherein the organic photoconducting material has a basic structure corresponding to phthalocyanine having the following general formula: ##STR1## wherein a central metal Me is selected from the group consisting of indium, gallium and aluminum, and X is a combined halogen, and the above phthalocyanine is the one in which some hydrogen of benzene rings positioned around the phthalocyanine ring of the above basic structure are substituted by the same halogen with the combined halogen, and furthermore the above organic photoconducting material may be a mixture of the former phthalocyanine and the latter phthalocyanine.