Mitsubishi Denki Kabushiki Kaisha

Yuji Ohkura

Motoharu Miyashita

Hirotaka Kizuki

Shoichi Karakida

Harumi Nishiguchi

Masatoshi Fujiwara

Yutaka Mihashi

Tohru Takiguchi

Norio Hayafuji

Yasuaki Yoshida

Masayoshi Takemi

Akihiro Shima

Yasutomo Kajikawa

Akihiro Takami

Kotaro Mitsui

Seiji Ochi

Kazuo Mizuguchi

Mari Tsugami

Manabu Katoh

Zenpei Kawazu

A forward mesa ridge-embedded semiconductor laser device provides a high power output and includes a base portion of a forward mesa ridge having a narrow width to stabilize transverse mode oscillation and an upper cladding layer having a thickness sufficient to reduce loss of the laser beam, a top portion of the forward mesa ridge being interposed between parts of the current blocking layer to reduce the device resistance. The upper cladding layer includes a first cladding layer having the forward mesa ridge and a second cladding layer opposite the first cladding layer. The second cladding layer is deposited over the first cladding layer through the forward mesa ridge and a current blocking layer is positioned on both sides of the forward mesa ridge.

Semiconductor laser device and process for manufacturing the same

A semiconductor laser diode includes a p-type GaAs semiconductor substrate, a p-type region which includes a p-type AlGaAs lower cladding layer, an active layer and an n-type region which includes an n-type AlGaAs upper cladding layer, wherein the n-type AlGaAs upper cladding layer is Al.sub.x Ga.sub.1-x As (x.gtoreq.0.4) having a carrier concentration of no more than 6.times.10.sup.17 cm.sup.-3.

Semiconductor laser diode

A semiconductor laser includes a first conductivity type GaAs substrate; a AlGaAs double heterojunction structure disposed on the GaAs substrate and including an upper cladding layer having a mesa ridge stripe with a side surface that makes an angle larger than 90.degree. with a front surface of the upper cladding layer; a first current blocking layer of first conductivity type AlGaAs; and a second current blocking layer of first conductivity type AlGaAs, the first and second current blocking layers covering the mesa ridge stripe. The Al compositions of the first and second current blocking layers are larger than that of the upper cladding layer, maintaining an equivalent refractive index of an active region higher than that of other portions of the semiconductor laser. As a result, the differences between the lattice constant of the second current blocking layer and the GaAs substrate or the AlGaAs upper cladding layer are smaller than in prior art semiconductor lasers. Since the second current blocking layer is in the vicinity of the active region in the mesa ridge stripe, stress applied to the active region is reduced, thereby producing a semiconductor laser that facilitates ridge width control and burying layer growth, and with improved reliability.

Semiconductor laser

A method of fabricating a semiconductor laser device includes successively forming an active layer and upper cladding layers on a lower cladding layer, etching and removing portions except regions of the upper cladding layers where a current is to flow to form a stripe-shaped ridge structure, and forming a buffer layer comprising Al.sub.x Ga.sub.1-x As having an Al composition ratio x of 0 to 0.3 on a surface of the upper cladding layers exposed by the etching and forming a current blocking layer of first conductivity type Al.sub.y Ga.sub.1-y As having an Al composition ratio y of at least 0.5 on the buffer layer to bury portions of the upper cladding layers which are not removed by the etching process. Therefore, since the layer grown on the upper cladding layer exposed by etching of AlGaAs or GaAs having a low Al composition ratio (0-0.3), three-dimensional growth of and crystalline defects in the buffer layer are suppressed. Current leakage is suppressed, so that a semiconductor laser device having a low threshold current and a high efficiency is fabricated with a stable yield.

Semiconductor laser device and method of fabricating semiconductor laser

In a thermal radiation type substrate heating system of an MOCVD growth apparatus, a susceptor includes a semi-circular concavity is formed in each of wafer pockets at the forward area in a wafer rotation direction so that P-richness in a crystalline film grown at the gas upstream area is suppressed. Specifically, the conventional wafer holder exhibits a non-uniform temperature distribution so that the surface temperature is high at the gas upstream area and low at the downstream area. On the other hand, the structure according to the present invention realizes a high temperature at a wafer contact area and a low temperature at a wafer non-contact area, thus leading to a uniform surface temperature over the entire gas upstream and downstream areas.

Vapor-phase growth apparatus and compound semiconductor device

A semiconductor laser device includes a first conductivity type GaAs substrate; a first conductivity type first lower cladding layer disposed on the GaAs substrate, lattice-matching with the GaAs substrate, and having an energy band gap; a first conductivity type AlGaAs second lower cladding layer disposed on the first lower cladding layer and having an energy band gap larger than the energy band gap of the first lower cladding layer; an active layer disposed on the second lower cladding layer and having an energy band gap smaller than the energy band gap of the first lower cladding layer; a second conductivity type AlGaAs second upper cladding layer disposed on the active layer and having an energy band gap; a second conductivity type first upper cladding layer disposed on the second upper cladding layer, lattice-matching with the GaAs substrate, and having an energy band gap larger than the energy band gap of the active layer and smaller than the energy band gap of the second upper cladding layer; a second conductivity type GaAs contact layer disposed on the first upper cladding layer; and first and second electrodes respectively disposed on the substrate and the contact layer. In this structure, the stress within the crystalline structure of the laser device is reduced and the crystalline defect density is reduced, whereby the reliability of the device is improved.

Semiconductor laser device

In a method for fabricating an infrared detector, initially, a CdHgTe layer of a first conductivity type is produced on a front surface of a semiconductor substrate, a plurality of spaced apart CdHgTe regions of a second conductivity type, opposite the first conductivity type, are produced at the surface of the first conductivity type CdHgTe layer, and part of the surface of the first conductivity type CdHgTe layer between the second conductivity type CdHgTe regions is selectively irradiated with a charged particle beam to evaporate Hg atoms from that part, whereby a CdHgTe separation region of the first conductivity type and having a Cd composition larger than that of the first conductivity type CdHgTe layer is produced penetrating through the first conductivity type CdHgTe layer and surrounding each of the second conductivity type CdHgTe regions. Therefore, a highly-integrated high-resolution infrared detector with no crosstalk between pixels is achieved.

Infrared detector having active regions and isolating regions formed of

A single wavelength oscillating semiconductor laser device having at least two diffraction gratings in an active region in which the order of a first diffraction grating disposed in the center of the laser is higher than that of a second diffraction grating disposed in the neighborhood of resonator facets.

Semiconductor laser including periodic structures with different periods

A method for manufacturing a diffraction grating includes applying a resist, the developing speed of which has an extreme at a certain exposure intensity, to a substrate on which the diffraction grating is to be formed, performing interference exposure of the resist with maximum and minimum values of exposure intensity respectively larger and smaller than the intensity which makes the developing speed an extreme, developing the resist, and etching the substrate using the remaining resist as a mask.

Method of manufacturing a diffraction grating for a semiconductor laser

In a method of producing an infrared detector, a first conductivity type semiconductor layer, in which lattice vacancies acting as first conductivity type carriers are formed by evaporation of an element during annealing, is formed on a substrate and dopant impurities producing a second conductivity type are diffused in an annealing step from the impurity layer into the first conductivity type semiconductor layer to form pixel regions. During the diffusion, the surface of the first conductivity type compound semiconductor layer corresponding to non-pixel regions is exposed. In the regions of the first conductivity type semiconductor layer which becomes non-pixel regions, the first conductivity type carrier concentration increases due to the lattice vacancies generated by the evaporation of an element and, even when the dopant impurity is diffused into these regions, these regions remain first conductivity type regions.

Method for producing an infrared detector

In a single wavelength oscillation semiconductor laser having a diffraction grating at the active region, the coupling coefficient between the light and the diffraction grating is low within the laser and high in the neighborhood of the resonator end surface. The amplitude of the diffraction grating is low within the laser and high in the neighborhood of the resonator end surface, or the active layer or the guide layer is thick within the laser and thin in the neighborhood of the resonator end surface. Thus, the laser oscillates at a single wavelength even at high power output operation.

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Tokyo, Japan

Yuji Ohkura