Abstract: The present invention provides an optical waveguide structure comprising plural periods of a multi-layered structure which comprises an InGaAs optical absorption layer of a first conductivity type, a pair of first and second InGaAsP cladding layers of the first conductivity type sandwiching the InGaAs optical absorption layer, and a pair of a first InP layer of the first conductivity type and a second InP layer of a second conductivity type, and the first and second InP layers sandwiching the first and second InGaAsP cladding layers.

Abstract: The present invention provides an optical waveguide structure comprising plural periods of a multi-layered structure which comprises an InGaAs optical absorption layer of a first conductivity type, a pair of first and second InGaAsP cladding layers of the first conductivity type sandwiching the InGaAs optical absorption layer, and a pair of a first InP layer of the first conductivity type and a second InP layer of a second conductivity type, and the first and second InP layers sandwiching the first and second InGaAsP cladding layers.

Abstract: A compound semiconductor multilayer structure includes a plurality of core layers absorbing light and exhibiting a photoelectric transfer; and a plurality of cladding layers, adjacent two of which sandwich each of the core layers so that the core layers are separated from each other by the cladding layers.

Abstract: A semiconductor light-receiving device including (a) a semiconductor substrate, (b) a multi-layered including a first buffer layer having a first electrical conductivity and lying on the semiconductor substrate, a first clad layer having a first electrical conductivity and lying on the first buffer layer, a light-absorbing layer having a first electrical conductivity and lying on the first clad layer, a second clad layer having a second electrical conductivity and lying on the light-absorbing layer, and a second buffer layer having a second electrical conductivity and lying on the second clad layer, (c) a first electrode formed on the second buffer layer, and (d) a second electrode formed on a lower surface of the semiconductor substrate. The multi-layered structure has at least one portion which is inclined to a direction in which a light introduced into the device is directed. For instance, the multi-layered structure has opposite end portions inclined to the direction.

Abstract: A semiconductor light-receiving device including (a) a semiconductor substrate, (b) a multi-layered including a first buffer layer having a first electrical conductivity and lying on the semiconductor substrate, a first clad layer having a first electrical conductivity and lying on the first buffer layer, a light-absorbing layer having a first electrical conductivity and lying on the first clad layer, a second clad layer having a second electrical conductivity and lying on the light-absorbing layer, and a second buffer layer having a second electrical conductivity and lying on the second clad layer, (c) a first electrode formed on the second buffer layer, and (d) a second electrode formed on a lower surface of the semiconductor substrate. The multi-layered structure has at least one portion which is inclined to a direction in which a light introduced into the device is directed. For instance, the multi-layered structure has opposite end portions inclined to the direction.

Abstract: A semiconductor photo detector has its construction such that on a substrate made of InP are formed light absorption layer having a supperlattice structure made of n- type InGaAsP and InAsP, an intermediate layer made of n- type InGaAs, a multiplication layer made of n- type InP and a layer made of p- type layer. The light having a wavelength 1.65 .mu.m being made incident into the detector from the p- type InP layer is absorbed in the superlattice structure light absorption layer of n- type InGaAs/InAsP and changed into carriers, which flowed out an external circuit. Since the superlattice of InGaAs and InAsP makes a lattice matching to InP, it may be possible to prevent that a dark current is generated by a lattice mismatching. The carriers generated by the absorbed light in the light absorption layer pass from the p type side electrode 11 into an external circuit via the n type InGaAsP intermediate layer 4, n+ type InP multiplication layer 5 and p+ type InP layer 8.

Abstract: An n.sup.- -InGaAs first photo-absorbing layer, an n.sup.+ -InP multiplication layer, and a p.sup.+ -type photo-incident region are formed on the first major surface of an n.sup.+ -InP substrate. An n.sup.- -InGaAs second photo-absorbing layer and a p.sup.+ -InP rear window layer are formed on the second major surface of the substrate. A p-side electrode, an n-side electrode and a transmission carrier absorption electrode are connected to the photo-incident region, the substrate and the rear window layer via contact electrodes, respectively. Since light passing through the first photo-absorbing layer is absorbed in the second photo-absorbing layer, it can be prevented that carriers are generated outside the depletion layer by light reflected by the rear surface. Thus, the trailing response characteristic of the avalanche photodiode (APD) in response to pulse incidental light can be improved.

Abstract: An avalanche photo-diode in the InP-InGaAs-InGaAsP system has a thin main photo-absorbing layer for converting light into carriers, and an auxiliary photo-absorbing layer and a protection layer are provided under the main photo-absorbing structure for absorbing residue of the light without attracting toward electrodes, thereby producing an photo-detecting signal with a sharp trailing edge.