A semiconductor light detector includes a first semiconductor layer of a first conductivity type having a multi-layer structure including a light absorbing layer and an avalanche multiplicating layer, an annular second semiconductor layer formed on the first semiconductor layer, a light detecting region formed by doping an impurity of a second conductivity type in a surface region of the first semiconductor layer, in such a manner that a peripheral portion of the light detecting region is located outside an inner periphery of the second semiconductor layer, the light deflecting region defining a first p-n junction in combination with the first semiconductor layer, and a guard ring formed by doping an impurity of the second conductivity type in a surface region of the second semiconductor layer to surround the peripheral portion of the light receiving region with the first semiconductor layer, the second p-n junction having a concentration gradient lower than that of the first p-n junction. By virtue of the presence of the second semiconductor layer, the junction depth of the peripheral portion of the light detecting region is less than that of the central portion of the light detecting region, and the junction depth of the guard ring is greater than that of the peripheral portion of the light detecting region. As a result, a sufficient guard ring effect can be obtained without a guard ring having a great junction depth.
Disclosed is a preferable method for producing an avalanche photo diode in which an impurity-doped region having a relatively high concentration and a step-like distribution has a step portion in another impurity-doped region having a relatively low concentration and a gradational distribution so that the circumferential portion of the high concentration region is made shallow in comparison with the central portion of the same, the step portion having a shape so that the radius of curvature thereof varies continuously.
A method for manufacturing semiconductor light-receiving elements is provided. The method includes the steps of forming an epitaxial layer including a light-receiving layer composed of at least In, Ga, and As on an n-InP substrate by supplying at least In gas, Ga gas, and As gas to a surface of the n-InP substrate from one side of a container accommodating the n-InP substrate, forming a p-type layer in the configuration of a floating island by thermally diffusing a p-type impurity into the light-receiving layer, and separating the n-InP substrate on which the p-type layer has been formed into semiconductor light-receiving elements.
A MISFET having a graded semiconductor alloy channel layer of silicon germanium in which the germanium is graded to a single peak percentage level. The single peak percentage level defines the location of the charge carriers within the layer. The transconductance of the device can be optimized by controlling the location of the carriers within the channel.
A dual gate thin film or SOI MOSFET device having a sufficiently thin body thickness with one or more semiconductor channel layer(s) sandwiched by semiconductor layers having a different energy band structure to automatically confine carriers to the channel layer(s) without the need for channel grading or modulation doping. Preferred embodiments employ strained layer epitaxy having Si/SiGe/Si or SiGe/Si/SiGe semiconductor layers.
A semiconductor photodetection device includes a semiconductor structure including an optical absorption layer having a photo-incidence surface on a first side thereof, a dielectric reflecting layer formed on a second side of the semiconductor structure opposite to the first side, a contact electrode surrounding the dielectric reflecting layer and contacting with the semiconductor structure, and a close contact electrode covering the dielectric reflecting layer and contacting with the contact electrode and the dielectric reflecting layer, wherein the close contact electrode adheres to the dielectric reflecting layer more strongly than to the contact electrode.
