Abstract: A semiconductor photodetector comprises: a semiconductor substrate; a first multilayer reflective layer on a first surface of the semiconductor substrate and including semiconductor layers; a first optically-resonant layer on the first multilayer reflective layer; a second multilayer reflective layer on the first optically-resonant layer and including semiconductor layers; a light absorbing layer on the second multilayer reflective layer; a reflective film on the light absorbing layer; and an antireflective film on a second surface of the semiconductor substrate. The first optically-resonant layer has a larger thickness than the semiconductor layers of the first and second multilayer reflective layers. The combined optical thickness of the layers between the second multilayer reflective layer and the reflective film is not equal to the optical thickness of the first optically-resonant layer.

Abstract: An optical semiconductor device includes a distributed Bragg reflection layer of a first conductivity type, a distortion elaxation layer of the first conductivity type, a light absorbing layer, and a semiconductor layer of a second conductivity type, sequentially arranged on a semiconductor substrate. The distortion relaxation layer the same material as the semiconductor substrate. The total optical length of layers between the distributed Bragg reflection layer and the light absorbing layer is an integer multiple of one-half the wavelength of incident light that is detected.

Abstract: An optical semiconductor device comprises a distributed Bragg reflector layer of a first conductivity type, an optical absorption layer, and a semiconductor layer of a second conductivity type, sequentially formed on a semiconductor substrate; wherein said Bragg reflection layer of the first conductivity type has first semiconductor layers having a band gap wavelength larger than the wavelength of incident light, and second semiconductor layers having a band gap wavelength smaller than the wavelength of incident light; and an optical layer thickness of each of said first semiconductor layers is larger than the optical layer thickness of each of said second semiconductor layers.

Abstract: A semiconductor light detecting device includes an n-contact layer selectively disposed on an Fe—InP substrate. An optical waveguide layer is disposed on the n-contact layer and includes an n-cladding layer, a light absorption layer, and a p-cladding layer, laminated on one another over the n-contact layer, in that order. An Fe—InP current blocking layer is disposed on the n-cladding layer such that sides of the optical waveguide layer are buried in the Fe—InP current blocking layer. A p-electrode includes a contact electrode electrically connected to the p-cladding layer of the optical waveguide layer, a lead-out electrode portion extending on a side wall of the current blocking layer from the contact electrode and extending on the Fe—InP substrate, and an electrode pad disposed on a surface of the Fe—InP substrates with an SiN film between the electrode pad and the surface of the Fe—InP substrate and connected to the lead-out electrode portion.

Abstract: A semiconductor photosensitive element comprises: a semiconductor substrate of a first conductivity type; a first light absorption layer, a first semiconductor layer of a second conductivity type, a first semiconductor layer of the first conductivity type, a second light absorption layer, and a second semiconductor layer of a second conductivity type, arranged in this order on the semiconductor substrate; a first electrode connected to the second semiconductor layer of the second conductivity type; a second electrode connected to the semiconductor substrate; and a third electrode electrically connecting the first semiconductor layer of the first conductivity type to the first semiconductor layer of the second conductivity type. The third electrode is located outside a light detection region for detecting optical signals.

Abstract: A semiconductor light detecting element comprises: a semiconductor substrate having a first major surface and a second major surface opposite each other; a first reflective layer, an absorptive layer, a phase adjusting layer, and a second reflective layer sequentially disposed, from the semiconductor substrate, on the first major surface of the semiconductor substrate; and an anti-reflection film on the second major surface of the semiconductor substrate, The first reflective layer is a multilayer reflective layer including laminated semiconductor layers having different refractive indices; the absorptive layer has a band gap energy smaller than band gap energy of the semiconductor substrate; the phase adjusting layer has a band gap energy larger than the band gap energy of the absorptive layer; and the first reflective layer contacts the absorptive layers without intervention of other layers.

Abstract: A semiconductor light detecting device includes an n-contact layer selectively disposed on an Fe—InP substrate. An optical waveguide layer is disposed on the n-contact layer and includes an n-cladding layer, a light absorption layer, and a p-cladding layer, laminated on one another, over the n-contact layer, in that order. An Fe—InP current blocking layer is disposed on the n-cladding layer such that sides of the optical waveguide layer are buried in the Fe—InP current blocking layer. A p-electrode includes a contact electrode electrically connected to the p-cladding layer of the optical waveguide layer, a lead-out electrode portion extending on a side wall of the current blocking layer from the contact electrode and extending on the Fe—InP substrate, and an electrode pad disposed on a surface of the Fe—InP substrate, with an SiN film between the electrode pad and the surface of the Fe—InP substrate and connected to the lead-out electrode portion.

Abstract: The present invention provides an avalanche photodiode capable of raising productivity. An n-type InP buffer layer, an n-type GaInAs light absorption layer, an n-type GaInAsP transition layer, an n-type InP electric field adjusting layer, an n-type InP avalanche intensifying layer, an n-type AlInAs window layer and a p-type GaInAs contact layer are grown in order on an n-type InP substrate. Next, Be is ion-injected into an annular area along the outer periphery of a light receiving area which is activated by heat treatment so as to form an inclined joint, to obtain a p-type peripheral area for preventing an edge break down. Further, Zn is selectively diffused thermally into the light receiving area until it reaches the n-type InP avalanche intensifying layer so as to form a p-type conductive area.

Abstract: An n-type InGaAs light absorbing layer and an n-type InP layer (first conductivity type semiconductor layer), which is a window layer, and a multiplication layer are multilayered one atop another on an n-type InP substrate. By selectively diffusing impurities and implanting ions, a p-type InP region second conductivity type semiconductor region) is formed on a part of the top surface of the n-type InP layer. The top surfaces of the n-type InP layer and p-type InP region are covered with a surface protection film. A cathode electrode (first electrode) is connected to the underside of the n-type InP substrate. A ring-shaped anode electrode (second electrode) is connected to the top surface of the p-type InP region. A low-voltage electrode surrounds the anode electrode. A voltage lower than that of the cathode electrode is applied to this low-voltage electrode.

Abstract: An avalanche photodiode according to this invention include a light receiving region 101 surrounded by a ring-shaped trench 13, a first electrode 11 formed on the light receiving region 101, a second electrode 12 formed on the periphery of the ring-shaped trench 13 surrounding the light receiving region, a first semiconductor layer lying just under the first electrode 11, and a second semiconductor layer lying just under the second electrode 12. Conductivity types of the first semiconductor and the second semiconductor are identical.

Abstract: A semiconductor light-receiving device and its manufacturing method are provided which are capable of suppressing dark current and deterioration. Semiconductor crystals were sequentially grown over an n-type InP substrate, including an n-type InP buffer layer, an undoped GaInAs light absorption layer, an undoped InP diffusion buffer layer, and a p-type InP window layer. Next, a first mesa was formed by removing a part from the p-type InP window layer to the n-type InP buffer layer with a Br-based etchant having low etching selectivity, so as to form a sloped “normal” mesa structure. Next, a second mesa having a smaller diameter than the first mesa was formed by dry etching, by precisely removing a part from the p-type InP window layer to a certain mid position of the undoped InP diffusion buffer layer.

Abstract: A buried-waveguide light detecting element includes an n-type cladding layer on a Fe-InP substrate, a waveguide on a portion of the n-type cladding layer, and in which an n-type light guide layer, an i-light guide layer having a refractive index equal to or higher than that of the n-type cladding layer and undoped or having an impurity concentration of 1×1017 cm?3 or less, lower than the impurity concentration in the n-type light guide layer, a light absorption layer having a refractive index higher than that of the i-light guide layer, a p-type light guide layer, and a p-type cladding layer are successively layered in mesa form, from the Fe—InP substrate, and a blocking layer on the Fe—InP substrate and in which side walls of the waveguide are embedded.

Abstract: A transmitted light absorption/recombination layer, a barrier layer, a wavelength selection/absorption layer, and an InP window layer having a p-type region are supported by an n-type substrate and arranged in that order. Light with a wavelength of 1.3 ?m reaches the wavelength selection/absorption layer through the InP window layer. Then, the light is absorbed by the wavelength selection/absorption layer and drawn from the device as an electric current signal. Light with a wavelength of 1.55 ?m reaches the transmitted light absorption/recombination layer through the barrier layer. Then, the light is absorbed by the transmitted light absorption/recombination layer, generating electrons and holes. These electrons and holes recombine with each other and, hence, disappear.

Abstract: An avalanche photodiode including a first electrode; and a substrate including a first semiconductor layer of a first conduction type electrically connected to the first electrode, in which at least an avalanche multiplication layer, a light absorption layer, and a second semiconductor layer of a second conduction type with a larger band gap than the light absorption layer are deposited on the substrate. The second semiconductor layer is separated into inner and outer regions by a groove formed therein, the inner region electrically connected to a second. With the configuration, the avalanche photodiode has a low dark current and high long-term reliability. In addition, the outer region includes an outer trench, and at least the light absorption layer is removed by the outer trench to form a side face of the light absorption layer. With the configuration, the dark current can be further reduced.

Abstract: A buried-waveguide light detecting element includes an n-type cladding layer on a Fe—InP substrate, a waveguide on a portion of the n-type cladding layer, and in which an n-type light guide layer, an i-light guide layer having a refractive index equal to or higher than that of the n-type cladding layer and undoped or having an impurity concentration of 1×1017 cm?3 or less, lower than the impurity concentration in the n-type light guide layer, a light absorption layer having a refractive index higher than that of the i-light guide layer, a p-type light guide layer, and a p-type cladding layer are successively layered in mesa form, from the Fe—InP substrate, and a blocking layer on the Fe—InP substrate and in which side walls of the waveguide are embedded.

Abstract: In an avalanche photodiode provided with a substrate including a first electrode and a first semiconductor layer, formed of a first conductivity type, which is connected to the first electrode, the configuration is in such a way that, at least an avalanche multiplication layer, a light absorption layer, and a second semiconductor layer having a bandgap that is larger than that of the light absorption layer are layered on the substrate; a second conductivity type conductive region is formed in the second semiconductor layer; and the second conductivity type conductive region is arranged so as to be connected to a second electrode. With the foregoing configuration, an avalanche photodiode having a small dark current and a high long-term reliability can be provided with a simple process.

Abstract: An avalanche photodiode has improved low-noise characteristics, high-speed response characteristics, and sensitivity. The avalanche photodiode includes a first conductivity type semiconductor layer, a second conductivity type semiconductor layer, a semiconductor multiplication layer interposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer, and a semiconductor light-absorbing layer interposed between the semiconductor multiplication layer and the second conductivity type semiconductor layer. The avalanche photodiode further comprises a multiplication suppressing layer which suppresses multiplication of charge carriers in the semiconductor light-absorbing layer, located between the semiconductor light-absorbing layer and the second conductivity type semiconductor layer.

Abstract: An objective is to provide an avalanche photodiode that is excellent in device characteristics such as reliability. An avalanche photodiode is provided, which includes a substrate 1 formed with a light receiving region 3 on a multiplication layer 119, and formed with layers of differing semiconductor type with the multiplication layer 119 intervening, a ring-shaped groove 7 formed on the end face of the substrate 1 on its light-receiving-region side, in such a way that the groove surrounds the light receiving region 3, and one or more steps 5 provided on a side wall of the ring-shaped groove 7, in a range of from ¼ to ¾ of the depth of the groove.

Abstract: An avalanche photodiode has improved low-noise characteristics, high-speed response characteristics, and sensitivity. The avalanche photodiode includes a first conductivity type semiconductor layer, a second conductivity type semiconductor layer, a semiconductor multiplication layer interposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer, and a semiconductor light-absorbing layer interposed between the semiconductor multiplication layer and the second conductivity type semiconductor layer. The avalanche photodiode further comprises a multiplication suppressing layer which suppresses multiplication of charge carriers in the semiconductor light-absorbing layer, located between the semiconductor light-absorbing layer and the second conductivity type semiconductor layer.

Abstract: The present invention provides an avalanche photodiode capable of raising productivity. An n-type InP buffer layer, an n-type GaInAs light absorption layer, an n-type GaInAsP transition layer, an n-type InP electric field adjusting layer, an n-type InP avalanche intensifying layer, an n-type AlInAs window layer and a p-type GaInAs contact layer are grown in order on an n-type InP substrate. Next, Be is ion-injected into an annular area along the outer periphery of a light receiving area which is activated by heat treatment so as to form an inclined joint, to obtain a p-type peripheral area for preventing an edge break down. Further, Zn is selectively diffused thermally into the light receiving area until it reaches the n-type InP avalanche intensifying layer so as to form a p-type conductive area.