Abstract: An optical semiconductor device includes a semiconductor substrate; a light receiving element formed on the semiconductor substrate; a light absorbing element formed on the semiconductor substrate and located adjacent to the light receiving element; and a semiconductor element formed on the semiconductor substrate and used for signal processing. The light absorbing element includes a fifth semiconductor layer, and a light absorption region in the light receiving element has a different structure from a light absorption region in the light absorbing element.

Abstract: An optical semiconductor device includes a phototransistor for receiving incident light. The phototransistor includes a collector layer of a first conductivity type formed on a semiconductor substrate, a base layer of a second conductivity type formed on the collector layer, and an emitter layer of a first conductivity type formed on the base layer. A thickness of the emitter layer is equal to or less than an absorption length of the incident light in the semiconductor substrate.

Abstract: An optical semiconductor device comprises a first semiconductor region of a first conductivity type and a second semiconductor region of a second conductivity type formed on the first semiconductor region. The device further comprises a third semiconductor region of the first conductivity type formed in a semiconductor layer, which is separated from the first and second semiconductor regions by an element separation region, and a fourth semiconductor region of the first conductivity type formed between a semiconductor substrate and third semiconductor region. The device further comprises a fifth semiconductor region of the first conductivity type formed across the semiconductor substrate and the first semiconductor region. An upper portion of the fifth semiconductor region penetrates into a specific depth of the first semiconductor region. Amplification of a current signal occurs when a reverse voltage is applied between the second semiconductor region and a surface portion of the third semiconductor region.

Abstract: A semiconductor photodetector device includes a light receiving operation section converting incident light to an electric signal and a current amplifying operation section amplifying the electric signal. The light receiving operation section includes: a first conductivity type semiconductor layer a formed on a first conductivity type semiconductor substrate; a second conductivity type first semiconductor region formed on the semiconductor layer; and a first conductivity type second semiconductor region formed on the semiconductor layer and separated from the first semiconductor region. The current amplifying operation section includes: the second semiconductor region; a second conductivity type third semiconductor region formed in the semiconductor substrate; a second conductivity type fourth semiconductor region formed on the third semiconductor region and separated from the second semiconductor region.

Abstract: An optical semiconductor device includes a light-receiving element on a semiconductor substrate of a first conductivity type, the light-receiving element including a light-receiving portion for converting incident light to an electrical current signal and performing a current amplification. The light-receiving portion includes: a semiconductor layer formed on the semiconductor substrate and having an impurity concentration substantially equal to or less than that of the semiconductor substrate; a first semiconductor region of a second conductivity type formed on the semiconductor layer and having an impurity concentration higher than that of the semiconductor layer; and a second semiconductor region of the first conductivity type selectively formed between the semiconductor substrate and the semiconductor layer and having an impurity concentration higher than those of the semiconductor substrate and the semiconductor layer.

Abstract: A transistor that forms an integrated circuit, a photo detector and a micromirror are mounted on the same semiconductor substrate in an optical semiconductor device of the present invention, which has an antireflection film that is formed on the photo detector, a first insulating film which is formed on the antireflection film and in which an opening is created in the state where the antireflection film is exposed, and an etching stopping film which is formed on the first insulating film and which has been left in the periphery around the opening in the first insulating film on the antireflection film and in the periphery around the portion above the micromirror.

Abstract: An optical semiconductor device includes a semiconductor substrate; a light receiving element formed on the semiconductor substrate; a light absorbing element formed on the semiconductor substrate and located adjacent to the light receiving element; and a semiconductor element formed on the semiconductor substrate and used for signal processing. The light absorbing element includes a fifth semiconductor layer, and a light absorption region in the light receiving element has a different structure from a light absorption region in the light absorbing element.

Abstract: An optical semiconductor device includes a first light receiving region and a second light receiving region provided on a substrate and the first and second light receiving regions include light receiving elements, respectively. A first anti-reflection film is formed in the first light receiving region of the substrate and a second anti-reflection film is formed in the second light receiving region of the substrate. The reflectance of the first anti-reflection film for a first wavelength range of light is lower than the reflectance of the second anti-reflection film for the first wavelength range of light and the reflectance of the second anti-reflection film for a second wavelength range of light which is different from the first wavelength range of light is lower than the reflectance of the first anti-reflection film for the second wavelength range of light.

Abstract: An optical semiconductor device includes a phototransistor for receiving incident light. The phototransistor includes a collector layer of a first conductivity type formed on a semiconductor substrate, a base layer of a second conductivity type formed on the collector layer, and an emitter layer of a first conductivity type formed on the base layer. A thickness of the emitter layer is equal to or less than an absorption length of the incident light in the semiconductor substrate.

Abstract: The semiconductor laser unit comprises a laser emission part having a plurality of semiconductor laser elements of different laser beam wavelengths, and a mirror part having an optical reflection film for reflecting laser beams emitted from the laser emission part. The mirror part is blocked out into a plurality of areas to which each laser beam emitted from each of the plurality of semiconductor laser elements enters, and at the same time the reflection film having high reflectance for the laser beams that enter selectively on the areas is provided in each of the plurality of areas.

Abstract: There is provided a light receiving circuit capable of preventing an output variation of the light receiving circuit due to a change in ambient temperature with a simple configuration. The light receiving circuit is provided with a photodiode 4 for LD power monitoring and an I-V amplifier 5 connected with a feedback resistor 13, wherein a light receiving section 16 of the photodiode 4 is covered with a protective film 19. Temperature dependences between a light transmittance of the protective film 19 in accordance-with a shift of a wavelength of a laser beam due to a change in ambient temperature, and a resistance value of the feedback resistor 13 are set in such a way that they may be mutually compensated and an output voltage from the light receiving circuit may be constant for a temperature change.

Abstract: A semiconductor photodetector device includes a light receiving operation section converting incident light to an electric signal and a current amplifying operation section amplifying the electric signal. The light receiving operation section includes: a first conductivity type semiconductor layer a formed on a first conductivity type semiconductor substrate; a second conductivity type first semiconductor region formed on the semiconductor layer; and a first conductivity type second semiconductor region formed on the semiconductor layer and separated from the first semiconductor region. The current amplifying operation section includes: the second semiconductor region; a second conductivity type third semiconductor region formed in the semiconductor substrate; a second conductivity type fourth semiconductor region formed on the third semiconductor region and separated from the second semiconductor region.

Abstract: A semiconductor photodetector device includes: a first semiconductor layer of a first conductivity type; and a second semiconductor layer of a second conductivity type formed on the first semiconductor layer and having a light-receiving region. The first semiconductor layer includes a first region containing an impurity of the first conductivity type at a high concentration and a second region formed on the first region and containing an impurity of the first conductivity type at a concentration lower than that of the first region. The second semiconductor layer includes a third region containing an impurity of the second conductivity type at a concentration higher than that of the second region and a fourth region formed on the third region and containing an impurity of the second conductivity type at a concentration higher than that of the third region.

Abstract: The semiconductor laser unit comprises a laser emission part having a plurality of semiconductor laser elements of different laser beam wavelengths, and a mirror part having an optical reflection film for reflecting laser beams emitted from the laser emission part. The mirror part is blocked out into a plurality of areas to which each laser beam emitted from each of the plurality of semiconductor laser elements enters, and at the same time the reflection film having high reflectance for the laser beams that enter selectively on the areas is provided in each of the plurality of areas.

Abstract: An optical semiconductor device includes a first light receiving region and a second light receiving region provided on a substrate and the first and second light receiving regions include light receiving elements, respectively. A first anti-reflection film is formed in the first light receiving region of the substrate and a second anti-reflection film is formed in the second light receiving region of the substrate. The reflectance of the first anti-reflection film for a first wavelength range of light is lower than the reflectance of the second anti-reflection film for the first wavelength range of light and the reflectance of the second anti-reflection film for a second wavelength range of light which is different from the first wavelength range of light is lower than the reflectance of the first anti-reflection film for the second wavelength range of light.

Abstract: There is provided a light receiving circuit capable of preventing an output variation of the light receiving circuit due to a change in ambient temperature with a simple configuration. The light receiving circuit is provided with a photodiode 4 for LD power monitoring and an I-V amplifier 5 connected with a feedback resistor 13, wherein a light receiving section 16 of the photodiode 4 is covered with a protective film 19. Temperature dependences between a light transmittance of the protective film 19 in accordance-with a shift of a wavelength of a laser beam due to a change in ambient temperature, and a resistance value of the feedback resistor 13 are set in such a way that they may be mutually compensated and an output voltage from the light receiving circuit may be constant for a temperature change.

Abstract: Since a plurality of light-receiving elements have heretofore led an electrode from a semiconductor substrate through an impurity-diffused and -buried region, series resistance has been relatively high, so that it has been difficult to improve the frequency characteristics of the light-receiving element. The present invention reduces parasitic capacitance by isolating the light-receiving elements from one another with insulator or dielectric isolation regions 6 and further reduces series resistance by making a direct contact with a P-type semiconductor substrate 2 functioning as an anode region through the medium of a conductor-buried region 11 formed by burying a low-resistance conductor in an opening formed in the isolation region 6, so that the frequency characteristics of the light-receiving element can be improved.

Abstract: A transistor that forms an integrated circuit, a photo detector and a micromirror are mounted on the same semiconductor substrate in an optical semiconductor device of the present invention, which has an antireflection film that is formed on the photo detector, a first insulating film which is formed on the antireflection film and in which an opening is created in the state where the antireflection film is exposed, and an etching stopping film which is formed on the first insulating film and which has been left in the periphery around the opening in the first insulating film on the antireflection film and in the periphery around the portion above the micromirror.

Abstract: A semiconductor photodetector device includes: a first semiconductor layer of a first conductivity type; and a second semiconductor layer of a second conductivity type formed on the first semiconductor layer and having a light-receiving region. The first semiconductor layer includes a first region containing an impurity of the first conductivity type at a high concentration and a second region formed on the first region and containing an impurity of the first conductivity type at a concentration lower than that of the first region. The second semiconductor layer includes a third region containing an impurity of the second conductivity type at a concentration higher than that of the second region and a fourth region formed on the third region and containing an impurity of the second conductivity type at a concentration higher than that of the third region.