Mitsubishi Denki Kabushiki Kaisha

Nobuaki Kaneno

Hitoshi Tada

Hirotaka Kizuki

Kenzo Mori

Takashi Murakami

Tadashi Kimura

Norio Hayafuji

Tetsuo Shiba

Kenji Ikeda

Tatuya Kimura

Yoshitatu Kawama

Yuji Okura

Takashi Motoda

Masayoshi Takemi

Shoichi Karakida

Shigeki Kageyama

Kazuhisa Takahashi

Syoichi Karakida

A substrate holder employed for MOCVD and supporting a wafer on which crystal growth proceeds includes a molybdenum holder body, a GaAs polycrystalline film with a flat surface grown on a part of the surface of the molybdenum holder body where the wafer is absent, and an InP polycrystalline film grown on the GaAs polycrystalline film. Each of the polycrystalline films is grown to a thickness of 0.3 .mu.m or more at a temperature higher than the epitaxial growth temperature of 575.degree. C. During the MOCVD process, the emissivity of the molybdenum substrate holder is stable at a value near the emissivity of the wafer on the substrate holder and, therefore, the decomposition ratio of PH.sub.3 gas on the substrate holder is stable at a value near the decomposition ratio on the wafer, whereby any variation of the incorporation ratio of P atoms in the grown InGaAsP, i.e., a variation of the composition of the InGaAsP, is reduced and run-to-run variations of the composition of the grown crystal are reduced.

Substrate holder for MOCVD

A semiconductor laser device includes a semiconductor substrate, upper and lower cladding layers each having a composition lattice-matching with the semiconductor substrate, which lower cladding layer is disposed on the semiconductor substrate, and an active layer having a quantum well structure interposed between the upper and lower cladding layers. The active layer includes alternating well layers and barrier layers and outermost guide layers, and these are arranged so that two of the barrier layers and the guide layers sandwich each well layer. The guide layers lattice-match with the upper and lower cladding layers, and the well layer has a lattice constant different from lattice constants of the two layers sandwiching the well layer, thereby applying a tensile strain to the well layer. The tensile strain reduces the effective mass of holes in the quantum well active layer, resulting in low threshold current, high efficiency, and high-power output.

Semiconductor laser device

A method for fabricating a semiconductor laser includes forming a double heterojunction structure on a first conductivity type semiconductor substrate; forming the double heterojunction structure into a stripe mesa shape by selective etching; successively growing a first conductivity type layer, a second conductivity type current blocking layer, and a first conductivity type current blocking layer on opposite sides of the mesa to embed the mesa; and adding an impurity from a surface of the first conductivity type current blocking layer to form impurity doped regions that electrically separate the second conductivity type current blocking layer from an upper part of the mesa at opposite sides of the mesa.

Method of making semiconductor laser

An apparatus for producing a compound semiconductor layer includes a first flow rate controller for adjusting flow rates of respective material source gases, a gas mixing pipe for mixing the respective material source gases, gas distributing pipes for distributing gases and connected to the gas mixing pipe, a second flow rate controller for adjusting flow rates of the material source gases flowing through the gas distributing pipes and for supplying the material source gases to a reaction tube, a pressure detector for detecting pressure in the gas mixing pipe, and a third controller responsive to the pressure detector for controlling the second flow rate controller to maintain a constant pressure in the gas mixing pipe. Retardation of the gases between the first and second flow rate controllers is avoided, improving thickness uniformity in grown layers.

Apparatus for producing compound semiconductor devices

A semiconductor laser device including a semiconductor substrate; a plurality of semiconductor layers including an AlGaAs layer epitaxially grown on said semiconductor substrate; a ridge having a reverse mesa shape and opposed sides formed of said plurality of semiconductor layers; an Al.sub.x Ga.sub.1-x As low temperature buffer layer (0.ltoreq..times..ltoreq.1) disposed on said AlGaAs layer at opposite sides of said ridge; a first semiconductor layer epitaxially disposed on said low temperature buffer layer at opposite sides of said ridge; and a second semiconductor layer epitaxially disposed on said ridge and said first semiconductor layer.

Semiconductor laser including ridge confining buffer layer

A semiconductor laser includes a first conductivity type semiconductor substrate; a double-heterojunction structure including a first conductivity type cladding layer, an active layer, and a second conductivity type cladding layer successively disposed on the semiconductor substrate; two parallel stripe grooves forming the double-heterojunction structure in a mesa shape; a first conductivity type mesa embedding layer, a second conductivity type current blocking layer, and a first conductivity type current blocking layer successively disposed on the semiconductor substrate and contacting opposite sides of the mesa; and impurity doped regions formed by adding an impurity through the surface of the first conductivity type current blocking layer. The impurity doped regions electrically separate an upper part of the mesa from the second conductivity type current blocking layer at opposite sides of the mesa. Since the second conductivity type current blocking layer is not in contact with the mesa structure, no leakage current path is formed in the laser structure.

Semiconductor laser

In a method for producing a semiconductor device, a first semiconductor layer is epitaxially grown on a semiconductor substrate, an insulating film pattern is formed on the first semiconductor layer, and portions of the first semiconductor layer are removed by wet etching using the insulating film pattern as a mask to leave a ridge having a reverse mesa shape and a width. Ends of the insulating film pattern are removed by etching to approximately the width of the ridge, a second semiconductor layer is epitaxially grown on opposite sides of the ridge, and a third semiconductor layer is epitaxially grown on the ridge and the second semiconductor layer. The second semiconductor layer is evenly grown without concave portions at opposite sides of the ridge. In addition, the third semiconductor layer is evenly grown on the ridge and the second semiconductor layer, and an electrode reliably connects the surface of the third semiconductor layer. A semiconductor device with good performance and high reliability is reproducibly manufactured.

Method for producing semiconductor device

A visible light semiconductor laser device has a double heterojunction structure comprising AlGaInP series semiconductors which is produced on a substrate having an electrode on its rear surface. A a p type GaInP buffer layer is provided between a p type GaAs contact layer and a p type AlGaInP cladding layer. The buffer layer has a constant composition ratio and the energy band gap is smaller at the side of the p type GaAs contact layer than at the p type AlGaInP cladding layer. Thus, an energy band discontinuity between the p type GaAs contact layer and the p type AlGaInP cladding layer are relaxed for operation of the laser at low voltage. The laser is produced by varying the growth conditions, such as temperature or V/III ratio during growth, of the buffer layer to vary the energy band gap within the buffer layer.

Method for producing a semiconductor laser device

A semiconductor laser having a double heterojunction structure includes a first semiconductor cladding layer having a stripe-shaped groove, a semiconductor active layer disposed on the cladding layer and having an energy band gap narrower than that of the cladding layer, and a second semiconductor cladding layer disposed on the active layer and having an energy band gap wider than that of the active layer. The thickness of the active layer in the groove is larger than the thickness of the active layer outside the groove and the shape of the active layer has the shape of the groove. The thickness of the active layer is largest in the bottom of the groove and gradually becomes smaller toward the edges of the groove. The semiconductor laser can output a laser beam having nearly a circular cross-section at a low threshold current and is easily fabricated.

A visible light semiconductor laser device has a double heterojunction structure comprising AlGaInP series semiconductors which is produced on a substrate having an electrode on its rear surface. A p type GaInP buffer layer is provided between a p type GaAs contact layer and a p type AlGaInP cladding layer. The buffer layer has a constant composition ratio and the energy band gap is smaller at the p type GaAs contact layer than at the p type AlGaInP cladding layer. Thus, an energy discontinuity between the p type GaAs contact layer and the p type AlGaInP cladding layer are relaxed for operation of the laser at lower voltage.

A semiconductor laser device which includes a semiconductor substrate; a semiconductor active layer; a semiconductor waveguiding layer provided adjacent to the active layer having a larger energy band gap than that of the active layer; a first and a second semiconductor cladding layer provided such that the semiconductor waveguiding layer and the active layer are positioned between by the two cladding layers, which cladding layers have larger energy band gaps than that of the waveguiding layer; and a periodic refractive index distribution being provided in a direction parallel with the active layer inside a waveguide produced by the refractive index differences produced at the above-mentioned four layers.

A semiconductor laser device which includes a first conductivity type semiconductor substrate; a first conductivity type first cladding layer, an active layer, and a second conductivity type second cladding layer successively provided on the substrate, wherein both the cladding layers have energy band gaps larger than that of the active layer; a first conductivity type current blocking layer having an energy band gap larger than that of the second cladding layer being provided on the second cladding layer, having a groove removed therefrom so as to form an exposed stripe portion on the second cladding layer; and a second conductivity type third cladding layer having an energy band gap smaller than that of the current blocking layer and larger than that of the active layer formed on the current blocking layer and on the stripe portion.

A bubbling evaporator comprises: a vessel (11); a partition plate (11a) for dividing the vessel (11) into an upper chamber (11b) for temporarily storing carrier gas and a lower chamber (11c) for containing liquid (2); an inlet pipe (12 or 14) for making the carrier gas blow from the upper chamber (11b) into the liquid (2) in the lower chamber (11c) through the partition plate (11a) to bubble and evaporate the liquid (2); and an outlet pipe (13) for leading the evaporated vapor together with the carrier gas to the exterior of the vessel (11). Thus, backflow of the liquid (2) to the exterior of the vessel (11) can be prevented and stable pressure of the evaporated vapor can be obtained. A method of evaporating a liquid organic metal to be used in a vapor deposition process for manufacturing semiconductor devices and the like is also disclosed.

Growing community of inventors

Itami, Japan

Nobuaki Kaneno