Abstract: A low-cost high-property optical semiconductor element for a long wavelength is provided, using a GaAs substrate. The optical semiconductor element comprises a substrate of GaAs having a first surface and a second surface opposite to each other, a buffer layer of InjGa1−jAs1−kNk (0≦j≦1, 0.002≦k≦0.05) formed on the first surface of the substrate, a first conductive type clad layer formed on the buffer layer, an active layer formed on the first conductive type clad layer and comprising a well layer of InzGa1−zAs (0≦z≦1), the well layer having a smaller bandgap than the first conductive type clad layer, the active layer having a thickness of more than its critical thickness for the substrate based upon equilibrium theories, and a second conductive type clad layer formed on the active layer and having a larger bandgap than the well layer.

Abstract: This invention is a semiconductor device including a p-type InP substrate having a mesa stripe in which at least an active layer and an n-type cladding layer are formed, and a semiconductor layer so formed as to bury the side surfaces of the mesa stripe and having at least an n-type current blocking layer and a p-type current blocking layer, wherein the n-type current blocking layer contains approximately 8.times.10.sup.17 cm.sup.-3 or more of Se as an impurity and the n-type current blocking layer and the n-type cladding layer are not contacting each other.

Abstract: Disclosed herein is an optical interconnection device having a light source, a plurality of optical interconnecting elements, and a light-receiving element. The optical interconnecting elements are located on an output side of the light source. Each of the elements has first and second major surfaces and comprises an integral unit made of an optical semiconductor element and a grating lens having concentric annular grooves and concentric annular projections, and two electrodes formed on the first and second major surfaces, respectively. The optical semiconductor element and grating lens of each optical interconnecting element are formed on the first major surface, for emitting or receiving light. The light-receiving element is located on an output side of the optical interconnecting elements. The optical interconnecting elements are arranged at substantially regular intervals, each positioned such that the semiconductor element and the grating lens face to the same direction.

Abstract: A microcavity semiconductor laser disclosed therein includes a double-heterostructure section including an intermediate active layer sandwiched between a first or lower cladding layer and a second or upper cladding layer above a semiconductive substrate. A first multi-layered reflector section is arranged between the substrate and the double-heterostructure section to have its reflectance which becomes maximum near the oscillation wavelength of the laser. The upper cladding layer is semi-spherically formed. A three-dimensional optical reflector covers the double-heterostructure section, for controlling spontaneous emission obtained in the double-heterostructure section along various directions, and for increasing the coupling ratio of spontaneous emission with a specific laser mode, thereby to decrease the threshold current.

Abstract: A microcavity semiconductor laser disclosed therein includes a double-heterostructure section including an intermediate active layer sandwiched between a first or lower cladding layer and a second or upper cladding layer above a semiconductive substrate. A first multi-layered reflector section is arranged between the substrate and the double-heterostructure section to have its reflectance which becomes maximum near the oscillation wavelength of the laser. The upper cladding layer is semi-spherically formed. A three-dimensional optical reflector covers the double-heterostructure section, for controlling spontaneous emission obtained in the double-heterostructure section along various directions, and for increasing the coupling ratio of spontaneous emission with a specific laser mode, thereby to decrease the threshold current.

Abstract: A p-type GaAs or AlGaAs thin film is formed by a MOCVD method. In the growing step of the thin film, the thin film is doped with a high concentration of carbon atoms forming an acceptor level such that the carrier concentration of the thin film falls within the range of between 1.times.10.sup.18 cm.sup.-3 and 1.times.10.sup.20 cm.sup.-3. At least one of trimethyl gallium and trimethyl aluminum is used as a raw material gaseous compound of III-group element, and arsine is used as a raw material gaseous compound of V-group element. The thin film is formed by an epitaxial growth under the molar ratio V/III of the V-group element supply rate to the III-group element supply rate, which is set at such a small value as 0.3 to 2.5, the temperature of 450 to 700.degree. and the pressure of 1 to 400 Torr. The thin film formed under these conditions exhibits a mirror-like smooth surface, and the film-growth rate is dependent on the supply rate of the V-group element.

Abstract: An impurity-doped double-heterostructure semiconductor laser adapted for single-longitudinal-mode operation is disclosed which includes a semiconductive substrate and a mesa of double-heterostructure formed over the substrate. The mesa comprises an active layer serving as a light-emitting layer, a waveguiding layer adjacent to the active layer and clad layers interposing the active layer and the waveguiding layer therebetween. A high-resistively layer is formed to bury the lateral surfaces of the mesa. The active layer contains impurities of a rare earth element with a previously selected concentration.