Patent number 8541734 is assigned to
The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to semiconductor structures, and particularly to avalanche amplification photodetectors and avalanche impact ionization transistors, and methods of operating the same.
"Currently available avalanche photodetectors require about 30V or more in order to achieve a usable level of amplification of generated photo-carriers. Further, currently available avalanche photodetectors require separate regions for absorption and amplification to achieve low noise operation, which are provided by growing various layers having different dopant concentrations and/or types. As a result, the currently available avalanche photodetectors tend to be bulky and expensive to manufacture.
"In addition, current amplification in semiconductor devices typically requires large bipolar devices that require additional processing steps than standard complementary metal oxide semiconductor devices.
"In view of the above, compact and effective devices for detecting photons and/or amplifying current are desired."
In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "A semiconductor photodetector that provides charge carrier amplification by impact ionization in high fields regions inside a semiconductor material layer and a semiconductor current amplifier that effecting current amplification by impact ionization inside a high field region are provided. A plurality of metal electrodes are formed on a surface of a semiconductor material layer and electrically biased to produce a non-uniform electric field in which the high electric field with strength close to avalanche breakdown accelerates electron-hole pairs over impact ionization threshold thus producing avalanche amplification which is employed as an effective photodetection mechanism or as a current amplification mechanism.
"According to an aspect of the present invention, a semiconductor structure is provided, which includes a semiconductor material layer having a doping of a same conductivity type throughout and located on a substrate; at least one first-type metallic electrode located over a top surface of the semiconductor material layer; at least one second-type electrode contacting the semiconductor structure; and a plurality of non-uniform high electric field regions with strength exceeding the impact ionization threshold located in the semiconductor material layer and around angled corners of the at least one first-type electrode, wherein the non-uniform electric field is generated by a voltage bias across the at least one first-type electrode and the at least one second-type electrode. The non-uniform field localized with sub-100 nm around the metal contact has field values higher than the impact ionization threshold of the semiconductor material.
"In one embodiment, the semiconductor structure further includes a current detection device configured to measure current that flows through the at least one first-type electrode and the at least one second-type electrode.
"In another embodiment, the semiconductor structure further includes at least one third-type electrode contacting the same semiconductor material layer; and a current detection device configured to measure current that flows through the at least one third-type electrode and the at least one second-type electrode, wherein the at least one first first-type electrode is located above a portion of the semiconductor layer including a path of the current.
"According to another aspect of the present invention, a method of operating a semiconductor device embodied in a semiconductor structure is provided. The method includes providing a semiconductor structure described above; inducing high electric field regions with strength exceeding impact ionization threshold to induce avalanche amplification of charge carriers in the semiconductor material layer described above; and detecting a change in current through a portion of the semiconductor material layer caused by the avalanche amplification, wherein the portion of the semiconductor material layer includes a portion located between a pair of the plurality of non-uniform high electric field regions.
"In one embodiment, the method further includes exposing the semiconductor material layer to electromagnetic radiation having an energy that is greater than a band gap of a semiconductor material of the semiconductor material layer, wherein the avalanche amplification of the carriers generated by the absorption of electromagnetic radiation is induced by high non-uniform electric field regions.
"In another embodiment, the method further includes providing a voltage bias across the at least one first-type electrode and the at least one second-type electrode."
URL and more information on this patent, see: Assefa, Solomon; Vlasov, Yurii A.; Xia, Fengnian. Avalanche Impact Ionization Amplification Devices. U.S. Patent Number 8541734, filed
Keywords for this news article include: Electronics, Semiconductor,
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