Abstract: In a semiconductor laser, a n-type AlGaInP clad layer is formed on a n-type GaAs substrate and an active layer having an emission wavelength of 600 to 850 nm is formed on the n-type AlGaInP clad layer. A p-type AlGaInP clad layer is formed on the active layer and a p-type AlGaAs contact layer in which the Al composition is controlled so that the p-type AlGaAs contact layer has an optical bandgap larger than that of the active layer is formed on the p-type AlGaInP clad layer. A p-type GaAs cap layer is formed on the p-type AlGaAs contact layer.

Abstract: In an optical semiconductor device including, at least, an n-type semiconductor layer having n-type conductivity, an active layer, a p-type semiconductor layer having p-type conductivity, current blocking layers doped with Fe are located on opposite sides of the p-type semiconductor layer. Fe and Be are simultaneously supplied as dopants when forming the p-type semiconductor layer. In this event, the flow rates of source materials supplying the respective elements are adjusted so that the p-type semiconductor layer has a hole concentration of about 1.0×1018/cm3 and an Fe concentration of about 2×1016 to 8×1016/cm3.

Abstract: In an optical semiconductor device including, at least, an n-type semiconductor layer having n-type conductivity, an active layer, a p-type semiconductor layer having p-type conductivity, current blocking layers doped with Fe are located on opposite sides of the p-type semiconductor layer. Fe and Be are simultaneously supplied as dopants when forming the p-type semiconductor layer. In this event, the flow rates of source materials supplying the respective elements are adjusted so that the p-type semiconductor layer has a hole concentration of about 1.0×1018/cm3 and an Fe concentration of about 2×1016 to 8×1016/cm3.

Abstract: A waveguide semiconductor optical device has a pin junction on a semi-insulating substrate. The pin junction consists of an n-type cladding layer, an i-type absorption layer, and a p-type cladding layer. The waveguide semiconductor optical device includes a dopant impurity concentration not higher than 1016 cm-3 in the i-type absorption layer.

Abstract: A distributed feedback semiconductor laser includes an n-InP substrate, an n-InGaAsP diffraction grating layer above the n-InP substrate, an AlGaInAs-MQW active layer above the diffraction grating layer and a ridge portion on the active layer. The ridge portion includes a p-InP cladding layer and a p-InGaAs contact layer. The wavelength ?g corresponding to the bandgap energy of the diffraction grating layer and the oscillation wavelength ? of laser light produced by the laser satisfy the relationship ??150 nm<?g<?+100 nm.

Abstract: A ridge waveguide semiconductor laser includes an active layer, semiconductor layers on the active layer and having a ridge-shaped waveguide, an insulating film on the semiconductor layer, a first electrode layer in contact with the semiconductor layer through an opening in the insulating film, and a second electrode layer on the first electrode layer having a stripe shape and extending along the waveguide. A distance from an end face of a resonator of the laser to an edge of the second electrode layer does not exceed 20 &mgr;m.

Abstract: In a semiconductor light-emitting device, an active layer has a multi quantum well structure (MQW) barrier layers and quantum well layers alternately arranged. Each of the cladding layers has a multi quantum barrier structure (MQB) including barrier layers and well layers alternately arranged. The multi quantum barrier (MQB) of each of the cladding layers varies in a graded or stepwise form. Thus, charge carriers are prevented from overflowing from the active layer, preventing cut-off of a guided wave mode, increasing reflectance of electrons entering the energy barriers, and improving temperature characteristics.

Abstract: A semiconductor optical device with improved optical gain and enhanced switching characteristics. The semiconductor optical device includes positive and negative electrodes for providing holes and electrons, respectively. The semiconductor optical device also includes an active layer between the positive and negative electrodes. The active layer includes a multiple quantum well structure having p-type quantum well layers and barrier layers. The quantum well layers are doped with an impurity that diffuses less than zinc so that trapping holes are produced and excessive electrons contributing no light emission are quenched by the trapping holes. The impurity can be beryllium, magnesium, or carbon.

Abstract: A laser device includes a double hetero-structure element constructed by depositing a p-type cladding layer, a quantum well active layer, an n-type thin first cladding layer and an n-type thick second cladding layer sequentially. A ridge-waveguide is shaped between two trenches formed in the second cladding layer. The first cladding layer serves as an etching stopper while etching the second cladding layer to form the two trenches. The trenches reach to or reach in vicinity to the surface of the first cladding layer. High-resistance regions may be formed in portions of the first cladding layer directly underneath the trenches. The thin first cladding layer, suppresses leakage current and improves the temperature characteristics and the operating speed characteristics of the laser device.

Abstract: The semiconductor laser device includes an active layer, a p-type cladding layer, and a p-type cap layer. The layers are sequentially stacked so that the semiconductor laser device is provided. The p-type cap layer includes both a p-type dopant and an n-type dopant. In another aspect, the p-type cap layer includes a first layer including a first p-type dopant and a second layer including a second p-type dopant having a diffusion coefficient smaller than that of the first p-type dopant. The first layer is far from the active layer, and the second layer is close to the active layer. In further aspect, the p-type cap layer includes carbon (C) as a p-type dopant. According to these configuration, the p-type dopant can be prevented from being diffused in the active layer and the p-type cladding layer.

Abstract: A waveguide-type semiconductor optical device (20) having a pin-type junction formed on a semi-insulating substrate (1). The pin-type junction consists of an n-type cladding layer (2), an i-type absorption layer (4), and a p-type cladding layer (6). The waveguide-type semiconductor optical device includes an impurity concentration of not higher than 1016 cm−3 in the i-type absorption layer.

Abstract: A distributed feedback laser device includes a semiconductor base having a ridge waveguide structure projecting from its principal plane. The ridge waveguide structure extends with a predetermined width from one edge of the semiconductor base to an opposite edge. A diffraction grating layer is confined within the ridge structure. The ridge waveguide structure is formed by etching using an SiO2 film and a resist film as masks so that the diffraction grating layer is produced with substantially the same width as, or a less width than, the width of the ridge waveguide structure. A &lgr;/4 shift diffraction grating or a chirped diffraction grating is preferably employed.

Abstract: In a semiconductor light-emitting device, an active layer has a multi quantum well structure (MQW) that a plurality of barrier layers and a plurality of quantum well layers are alternately arranged. Each of the cladding layers has a multi quantum barrier structure (MQB) that a plurality of barrier layers and a plurality of well layers are alternately arranged. A configuration of the multi quantum barrier (MQB) of each of the cladding layers varies in a graded or stepwise form. Thus, carriers are suppressed from overflowing from the active layer, preventing cut-off of a guided wave mode, increasing a reflectance of electrons entering the energy barriers and improving a temperature characteristic.

Abstract: A laser device includes a double hetero-structure element constructed by depositing a p-type cladding layer, a quantum well active layer, an n-type thin first cladding layer and an n-type thick second cladding layer sequentially. A ridge-waveguide is shaped between two trenches formed in the second cladding layer. The first cladding layer serves as an etching stopper while etching the second cladding layer to form the two trenches. The trenches reach to or reach in vicinity to the surface of the first cladding layer. High-resistance regions may be formed in portions of the first cladding layer directly underneath the trenches. The thin first cladding layer, suppresses leakage current and improves the temperature characteristics and the operating speed characteristics of the laser device.

Abstract: One aspect of the present invention has an object to provide a semiconductor optical device with an improved optical gain and an enhanced switching characteristics one aspect of the present invention is to provide a semiconductor optical device including a positive and negative electrodes for providing holes and electrons, respectively. The semiconductor optical device also includes an active layer provided between the positive and negative electrodes. The active layer includes a multiple quantum well structure having a plurality of quantum well layers and barrier layers. The quantum well layers are doped with a p-type impurity less diffusible than zinc so that a plurality of trapping holes are produced and a plurality of excessive electrons contributing no light emission are quenched by the trapping holes. The p-type impurity can be beryllium, magnesium, or carbon.

Abstract: An electrode for a semiconductor device includes a gold-containing thin film and a gold-containing plated film on the thin film. The plated film covers the entire thin film. No open surface is present between the thin gold film and the gold plating so no excessive current concentration occurs in any area.

Abstract: An electrode for power supply of a semiconductor device is disclosed. The electrode has a gold-containing thin film and a gold-containing plating formed on the thin film. The plating covers the entire thin film.

Abstract: A distributed feedback laser device is disclosed which comprises a semiconductor base having a ridge waveguide structure projecting from its principal plane, the ridge waveguide structure extending with a predetermined width from one edge of the semiconductor base to its opposite edge, wherein a diffraction grating layer is formed confined within the ridge structure. The ridge waveguide structure is formed by an etching process using an SiO2 film and a resist film as masks so that the diffraction grating layer is produced with substantially the same width as, or a less width than, the width of the ridge waveguide structure. A &lgr;/4 wavelength shift diffraction grating or a chirped diffraction grating may preferably be incorporated.