Hitachi, Ltd.

Makoto Kudo

Tomoyoshi Mishima

Mitsuhiro Mori

Takuma Tanimoto

Masataka Shirai

Kouji Nakahara

Masao Yamane

Shigehisa Tanaka

Chushiro Kusano

Misuzu Sagawa

Masahiko Kondow

Kiyoshi Ouchi

Takeshi Kitatani

Katsuhiko Higuchi

Akishige Nakajima

In the semiconductor laser or electro-absorption optical modulator that includes strained quantum well layers as active layers, making laser characteristics or modulator characteristics adequate has seen the respective limits since band structures, especially, &#x394;Ec and &#x394;Ev, have been unable to be adjusted independently. This invention is constructed by stacking an n-type InGaAlAs-GRIN-SCH layer, an MQW layer, a p-type InGaAlAs-GRIN-SCH layer, a p-type InAlAs electron-stopping layer, and others, in that order, on an n-type InP wafer; wherein the MQW layerincludes InGaAlAs-strained quantum well layers and InGaAlAsSb-formed barrier layers each having strain of an opposite sign to the strain applied to the quantum well layers.

Optical semiconductor device

In a semiconductor laser for emitting light perpendicular to substrate crystal, including, on the substrate crystal, an active layer for generating light, a cavity structure sandwiching the active layer by reflecting mirrors so as to obtain a laser beam from the light generated from the active layer, and a regrown semiconductor layer between the active layer and one of the reflecting mirrors, a regrown interface or a face very close to the regrown interface is formed by a thin film containing dopants of high concentration. With the configuration, an adverse influence of a contamination deposit on the regrown interface is eliminated by delta-doping the regrown interface. The cost is reduced and device resistance is also reduced to 50 &OHgr; or less. Thus, an edge emitting laser (VCSEL) for realizing a optical module achieving a high speed characteristic over 10 Gb/s is obtained.

Semiconductor laser, ray module using the same and ray communication system

A semiconductor laser which has an active layer of a lattice strain of less than 2% of a thickness mean on a GaAs substrate and can be used in a long wavelength band of 1.3 &mgr;m band or more and a photo module which uses the semiconductor laser are provided. The semiconductor laser device has a first semiconductor layer and second semiconductor layers , the layer and the layers forming a type-II heterojunction structure, in which an energy of conduction band edge of said first conductor layer is larger than the energy of conduction band of said second semiconductor layers . The device has third semiconductor layers as barrier layers formed on both sides of said type-II heterojunction structure. In the device, the second semiconductor layers are arranged on both sides of the first semiconductor layer and the thickness of the first semiconductor layer is set in such a degree of thickness that a wave function of an electron of a quantum well formed by making the second semiconductor layer well layers is coupled.

Semiconductor laser and photo module using the same

A semiconductor device has a lattice-mismatched crystal structure including a semiconductor film formed on a substrate with an intervening buffer layer. The buffer layer has a plurality of layers, including first sublayers, or regions, in which an element that controls the lattice constant is provided in increasing mole fraction, and second sublayers, or regions, in which the lattice constant is maintained. The first sublayers and second sublayers are provided in alternating fashion. The resulting device has an increased electron mobility as compared with the prior art.

Lattice-mismatched crystal structures and semiconductor device using the

In a semiconductor device using tunnel current and a barrier layer, arrangements are provided to lower the resistance of the semiconductor device. In particular, arrangements are provided to lower the parasitic resistance of a device such as a field effect transistor or an HBT, as well as to provide high-performance low noise amplifiers, mixers and the like using such reduced resistance semiconductor devices. To achieve this reduced resistance, carrier concentration or effective mass is designed not to be uniform in at least one of the semiconductor layers holding a barrier layer therebetween. For example, in an area near the barrier layer, the carrier concentration distribution can be large or the effective mass distribution can be small.

Semiconductor device with reduced tunnel resistance and circuitry using

A semiconductor crystalline laminate structure wherein between a first semiconductor layer consisting of a first alloyed semiconductor and a second semiconductor layer which has an energy gap wider than that of the first alloyed semiconductor and a lattice constant smaller than that of the first alloyed semiconductor and consists of one semiconductor selected from a group of single-element semiconductor, compound semiconductor, and alloyed semiconductor which contain no semiconductor having a largest lattice constant among the semiconductor constituting the first alloyed semiconductor, a third semiconductor layer which consists of a second alloyed semiconductor having an energy gap wider than that of the first alloyed semiconductor and contains the semiconductor having a largest lattice constant among the semiconductors constituting the first alloyed semiconductor is formed in contact with these layers, a forming method for the semiconductor crystalline laminate structure, and a semiconductor device using the method are indicated.

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Hamura, Japan

Makoto Kudo