Abstract: Disclosed is a method of growing 4 gallium nitride-based crystal by vapor phase epitaxy, suitable for mass production, without the necessity of thermal processing after completion of the crystal growth. The temperature of the substrate crystal immediately after completion of the crystal growth is 700.degree. C. or higher, and cooling of the substrate crystal at 700.degree. C. or lower after completion of the crystal growth is performed in an atmosphere of a hydrogen-fee carrier gas.

Abstract: A crystal growth method for growing on a gallium arsenide (GaAs) substrate a gallium nitride (GaN) film which is good in surface flatness and superior in crystallinity. According to the method, a GaAs substrate having a surface which is inclined with respect to the GaAs(100) face is used. The inclination angle of the substrate surface is larger than 0 degree but smaller than 35 degrees with respect to the GaAs(100) face. The inclination direction of the substrate surface is within a range of an angular range from the ?0,0,1! direction of GaAs to the ?0,-1,0! direction past the ?0,-1,1! direction and angles less than 5 degrees on opposite sides of the angular range around an ?1,0,0! direction of gallium arsenide taken as an axis, or within another range crystallographically equivalent to the range. The GaN layer is formed on the surface of the GaAs substrate preferably by hydride vapor deposition method.

Abstract: In a heterostructure III-V nitride semiconductor device, an InP substrate has a surface having a sloped angle of 0.degree. to 16.degree. with respect to a (100) surface thereof. At least one GaN layer is formed on the InP substrate.

Abstract: A gallium nitride type compound semiconductor light emitting element, such as a semiconductor laser, a light emitting diode is constructed by forming an In.sub.0.06 Ga.sub.0.94 N buffer layer, an n-type In.sub.0.06 Ga.sub.0.94 N clad layer, an n-type In.sub.0.06 Al.sub.0.15 Ga.sub.0.79 N clad layer, an undoped GaN active layer having layer thickness of 50 nm, a p-type In.sub.0.06 Al.sub.0.15 Ga.sub.0.79 N clad layer and a p-type In.sub.0.06 Ga.sub.0.94 N cap layer on a (0001) azimuth sapphire substrate. A p-side electrode is formed on the p-type In.sub.0.06 Ga.sub.0.94 N cap layer, and an n-side electrode is formed on the n-type In.sub.0.06 Ga.sub.0.94 N clad layer. In the construction set forth above, a greater thickness for the active layer is provided. Also, tensile strain is applied to the active layer. Light is taken out in parallel direction to the substrate. This threshold current of the semiconductor laser is lowered and light emitting efficiency of the light emitting diode is improved.

Abstract: A stripe structure including an MQW active layer has a width equal to or smaller than twice the diffusion length of holes, and a p type semiconductor layer for injecting holes into the MQW active layer is formed on both sides of the stripe structure in contact with the sides of the stripe structure. Even when any MQW structure is used as the MQW active layer in order to reduce the temperature dependency of the threshold current, holes are injected into QW layers from the p type semiconductor layer which is in direct contact with all the QW layers in the MQW active layer, so that no local presence of holes in some QW layers occurs. Since the width of the stripe structure is equal to or smaller than twice the diffusion length of holes, the holes are uniformly injected in the direction parallel to the QW surface.

Abstract: A refractive index control optical semiconductor device includes a semiconductor p-n junction structure, and a refractive index control semiconductor layer. The semiconductor p-n junction structure outputs light with a forward current. The refractive index control semiconductor layer is formed on a semiconductor substrate, is stacked on the semiconductor p-n junction structure to constitute an optical waveguide, causes a refractive index change of light to occur by carrier injection, and includes a multi-quantum well structure formed by alternately stacking a semiconductor quantum well layer and a barrier layer having a bandgap larger than that of the semiconductor quantum well layer at a plurality of periods. The semiconductor quantum well layer has a lattice constant smaller than that of the semiconductor substrate.