Abstract: A waveguide type semiconductor photodetector comprises a n-InP substrate, and a laminate including a first and second optical confinement layers and an undoped optical absorption layer interposed therebetween. The optical absorption layer has a thickness between 0.2 and 0.5 .mu.m, and a bandgap wavelength smaller than the bandgap wavelength of the first and second optical confinement layers. The photodetector has a large mode field diameter and a small coupling loss between the same and a glass fiber.

Abstract: A field effect transistor having an excellent transfer conductance and an improved gate leakage current and breakdown voltage is provided. In the transistor, a multiquantum barrier structure 4 is arranged between a gate and a channel layer 3 along a channel layer 3 and having an effect of reflecting incident overflowing carriers a s waves in with with phase conditions of total reflection allowing mutual enhancement of the incident and reflected wave in a region between a channel layer 3 and a gate electrode 10 and/or in a region opposite to the gate electrode 10 relative to the channel layer 3.

Abstract: A waveguide type light receiving element (10) comprises a photodetector section (14), a photo-attenuator section (18), and an electrical isolation section (20) having a light transmission property which electrically isolates the photodetector section from the photo-attenuator section for allowing light transmission. The photodetector section comprises n-type light guide layer (28) and i-type light absorption layer (30) formed on a substrate (22), and a pair of n- and p-type light confinement layers (26 and 32) which sandwich the light guide layer and the light absorption layer therebetween, thereby forming a double hetero junction structure. The photo-attenuator section has a layer structure similar to the photodetector section except for a strained MQW layer disposed instead of the light absorption layer and has an absorption controlling electrode (16) and an electrode (40) disposed on the top and bottom, respectively, of the substrate.

Abstract: The present invention provides a semiconductive light-emitting device involving a light-emitting layer of the multilayer strained quantum well structure that has a plurality of quantum well layers and a plurality of barrier layers, where each of said quantum well layers is constituted of a semiconductive crystal subjected to intraplanar compressive strain; each of the barrier layers is constituted of semiconductor crystal of AlInAs, AlGaInAs or AlGaInAsP. For high differential gain, each quantum well layer is 6nm thick or less, and the summed quantum well layers measure 13 to 1000 nm in thickness.

Abstract: A photo diode in which an optical absorption layer and a p-type semiconductor layer neighboring on each other are designed to be at almost the same valence band level (their offset not exceeding 0.05 eV). Preferably the optical absorption layer is a GaInAsP layer with an absorption edge wavelength of 1.65 to 1.55 .mu.m, and the p-type semiconductor layer and lattice-matching with the preceding semiconductor layer are each an AlGaInAs layer with an absorption edge wavelength of 1.55 to 1.30 .mu.m remaining shorter than that of the optical absorption layer.

Abstract: There is provided a semiconductor device comprising a Schottky junction having a very low leakage current and a high forward voltage. The device comprises a Schottky junction realized by a semiconductor 4 and a metal 6 and a multiquantum barrier structure 5 disposed on the interface of said semiconductor 4 and said metal 6 and having an effect of reflecting incident carriers as waves ?in phase conditions capable of allowing mutual enhancement of the incident and reflected waves!.

Abstract: The present invention provides an optical semiconductive device of a type wherein current is laterally injected toward the MQW structure to exhibit impartial distribution of carriers, low threshold current, enhanced optical output and improved response speed, in which an active layer has MQW structure 34, inplanar compression strain is included at least in well layer 34a or barrier 34b. The latent inplanar compression strain produces compressive stress, which serves to vary an energy bandwidth when injecting current in parallel with the MQW structure 34, so as to lessen effective mass of heavy holes; accordingly, those holes are accelerated, where carriers are impartially distributed to improve the device performance.

Abstract: There is provided an MSM type semiconductor photodetector having a strained superlattice structure that shows a high responsiveness and, at the same time, a reduced dark current. Such a strained superlattice semiconductor photodetector comprising semiconductor layers including a photodetective layer having an intra-planar compressive strain type strained superlattice layer formed on a semiconductor substrate by epitaxial growth is characterized in that the epitaxially grown layers are partly removed from the side walls of the semiconductor layers to produce cut-out sections (grooves 8a, 8b) and arranging electrodes in said cut-out sections respectively. Consequently, the fast responsiveness of the semiconductor photodetector is remarkably improved and the dark current of the device is greatly reduced.

Abstract: There is provided a semiconductor optical device having remarkable features including a low threshold current, a high light emitting efficiency, a high and stable optical output, a fast modulation capability, a large gain characteristics, resistance against oxidization, a high quality and a high degree of processibility. The device comprises a pair of optical confinement layers 13, 17 and a pair of cladding layers 12 and 18 arranged on and under an active layer 15 to produce a SCH structure, at least one of said optical confinement layers 13 and 17 comprising multiquantum barrier (MQB) structures 14, 16 as part thereof. If the active layer 15 is of multiquantum well type, the barrier layer 15a of the active layer 15 also comprises a multiquantum barrier (MQB) structure. With such an arrangement, the barrier height of the barrier layer 15a and the optical confinement layers 13, 17 can be made very high relative to the active layer 15 (well layer 15b).

Abstract: To provide a Schottky junction device having a super-lattice arranged in the Schottky interface in order to secure a high Schottky barrier and at the same time showing a high speed response by resolving the phenomenon of piled-up holes at the upper edge of the valence band, while maintaining the height of the Schottky barrier. A Schottky junction device having a Schottky junction of a semiconductor and a metal and a superlattice on the interface of the semiconductor and the metal, wherein the upper edge of the valence band of said superlattice is varied to show a turn to a specific direction. The phenomenon of hole-piling up at the upper end of the valence band is resolved while maintaining the height of the Schottky barrier and consequently such a Schottky junction device shows an excellent high speed response.

Abstract: There is provided a strained superlattice light emitting device for emitting light with a wavelength band around 0.8 .mu.m that is free from polarization dependency or can emit light either in the TE or TM mode with an output level much higher than that of an ordinary bulk layer, regardless of the density of injected current or carriers. Such a device comprises an InP substrate 1 and a pair of latticematched cladding layers 2 and 6 arranged on the substrate 1 and including first and second conductive type Al(Ga) InAs layers and an active layer 4 sandwiched by the pair of cladding layers 2 and 6 and having a strained superlattice structure, wherein the well layers 4a and 4b of the active layer 4 strained superlattice structure are respectively a GaInAsP layer showing an inplane tensile strain of 0.3 to 3% relative to the substrate and a GaInAsP layer showing an in-plane compressive strain of 0.

Abstract: A semiconductor laser device comprising a semiconductor substrate, a multi-layered double heterostructure having active layers, a pair of cladding layers, a ridged waveguide structure and a current confining structure formed between the semiconductor substrate and the active layer. With such an arrangement, injected current is narrowed not only on the side above the ridge of the active layer but also on the substrate side of the active layer to improve the threshold current and its current confinement performance. When the two lateral trenches of the ridge are embedded with resin layers, the ridge stripe width can be made narrow to improve the threshold current of the device. When the active layer is realized in a DCC structure having two active layers and having an intermediary clad layer sandwiched therebetween, the device will show a low threshold current circular beam divergence and stabilized thermal characteristics.

Abstract: There is provide a method of manufacturing a compound semiconductor (MBE) that can make the substrate surface of the semiconductor highly clean and plane so that no impurity may be left between the substrate surface and the grown crystal layer. In the step of cleaning a substrate with MBE, the substrate surface is irradiated with V molecular beams that cannot be significantly deposited out of molecular beams to be used for the crystal growth step, said V molecular beams being irradiated under a condition of P.sub.1 .ltoreq.(P.sub.2 .times.1/2), where P.sub.1 is the pressure of V molecular beams and P.sub.2 is the pressure of molecular beams in the crystal growth step and the temperature of the substrate surface is raised by heating until stabilized group III surfaces appear on the substrate surface. A very cleanand smooth substrate surface can be obtained with such an arrangement. Harmful impurities can be completely eliminated from the interface of the substrate and the crystal.

Abstract: There is provided a semiconductor laser device capable of emitting a laser beam having stable transverse modes. A ridge type semiconductor laser device comprises an upper clad layer 15 left on its active layer to a thickness (d) between 0.25 and 0.50 m in order to ensure a stable production of fundamental transverse modes for laser operation and a rib-shaped clad layer 16 having a bottom width (W) between 2.0 .mu.m and 3.5 .mu.m and projecting from the upper clad layer in juxtaposition with the light emitting region of the active layer 13. When d and W are found within the respective ranges, the device emits a laser beam having stable transverse modes.

Abstract: There is provided a semiconductor device comprising a current confinement structure capable of reducing leakage currents. The semiconductor device comprising a current confinement structure and a multiquantum barrier structure 10 disposed in said current confinement structure and having an effect of reflecting incident carriers as waves in phase conditions capable of allowing mutual enhancement of the incident and reflected waves.

Abstract: This invention provides a blue light semiconductor optical device capable of effectively oscillating in a temperature range above room temperature. A double hetero structure semiconductor optical device according to the invention is made of a compound semiconductor containing Zn and/or Cd as group II elements and S and/or Se and/or Te as group VI elements and comprises an active layer, a light confining layer and a cladding layer arranged on a semiconductor substrate as well as a multiquantum barrier structure having a strained superlattice layer in part of the cladding layer or the light confining layer for an effect of reflecting incident carriers as waves in phase conditions capable of allowing mutual enhancement of the incident and reflected waves.

Abstract: A semiconductor laser device comprising a semiconductor substrate, a multi-layered double heterostructure having active layers, a pair of cladding layers, a ridged waveguide structure and a current confining structure formed between the semiconductor substrate and the active layer. With such an arrangement, injected current is narrowed not only on the side above the ridge of the active layer but also on the substrate side of the active layer to improve the threshold current and its current confinement performance. When the two lateral trenches of the ridge are embedded with resin layers, the ridge stripe width can be made narrow to improve the threshold current of the device. When the active layer is realized in a DCC structure having two active layers and having an intermediary clad layer sandwiched therebetween, the device will show a low threshold current circular beam divergence and stabilized thermal characteristics.

Abstract: The quantum barrier semiconductor optical devices according to this invention are characterized by strained layer super lattice multiple quantum barriers provided between active layer and p-clad layer or within p-clad layer to obtain resonance scattering of incident overflowing electrons, that is to realize phase condition in which the incident overflowing electron wave and reflected electron wave enhance each other, in the double heterostructure where active layer having at least one GaInAs(P) layer is sandwiched between n-clad layer and p-clad layer. In this case, the active layer should desirably have quantum well structure.

Abstract: A semiconductor optical device comprising a mesa shaped double heterostructure having an active layer on an InP substrate, and pn junction current blocking layers embedded at all sides of the said double heterostructure, wherein at least portion of said current blocking layers consists of a semiconductor layer lattice-matched to InP and having a band gap larger than that of the InP at a room temperature. Therefore, the current blocking characteristics of the current blocking layer is improved so that the increase of leakage current under operating condition of high temperature and high output power is well suppressed, and the nonlinearity in the optical output-current characteristic is drastically reduced even under such operating conditions.

Abstract: A semiconductor laser diode of pn double hetero junction type which comprises a first active layer formed on a substrate for imparting a main oscillation, a second active layer adjacent to the first active layer in such a manner that at least one of the first and second active layers is formed of a multi quantum well or single quantum well structure, an intermediate clay layer interposed between the first active layer and the second active layer for preventing duplication of wave function of confined electrons of the respective active layers, and a graded refractive index distribution region (GRIN-SCH structure layer) provided on at least one of under the first active layer and over second active layer to reduce the refractive index thereof remotely from the active layers.