Abstract: An electronic parts mounting device according to this invention is characterized by including a mount body which is obtained by bonding at least two substrates each having a predetermined thicknesses and a smooth surface and which has at least one bonding portion, the mount body having at least one recessed portion selectively formed in one exposed surface of the mount body to reach the bonding portion, and the recessed portion having a tapered shape widened from the bonding portion to the exposed surface, and an electronic part mounted in the recessed portion.

Abstract: In an integrated optical semiconductor device having an InGaAsP optical waveguide and an InGaAs light absorption layer integrated together therein, the light absorption layer is formed to become gradually thicker in a traveling direction of light in the optical waveguide so that the effective absorption coefficient of the light absorption layer with respect to the optical waveguide can be set to become gradually larger in the traveling direction in the optical waveguide.

Abstract: A semiconductor photo-detector having a two-stepped impurity profile comprises a semiconductor substrate, a light absorption layer of a first conductivity type formed on a semiconductor substrate, a multiplication layer of a first conductivity type formed on the light absorption layer to multiply a photocurrent, a semiconductor region of a second conductivity type formed on the multiplication layer and constituting an abrupt pn junction with the multiplication layer, and a guard ring area of a second conductivity type formed around a periphery of the semiconductor region, whereby the carrier concentration profile of the guard ring region is sharp at its surface and flat below that surface.

Abstract: The invention discloses a method including the following processes (a) through (c) for forming impurity regions in a semiconductor device (a) a process that forms at least one second conductive type impurity-doped region by doping second conductive type impurity selectively to a predetermined region of a first conductive type semiconductor layer constituting a semiconductor substrate, (b) a process that forms on the surface of the semiconductor substrate a diffusion mask having a first opening for exposing at least one of the second conductive type impurity regions and having a second opening for exposing a part adjacent to at least one of the second conductive type impurity regions, (c) a process that forms the second conductive type impurity region and a low concentration second conductive type impurity region being in contact with the former by out-diffusing through the first opening the second conductive type impurity of the second conductive type impurity region and re-doping the out-diffused impurity th