The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 14, 1996
Filed:
Jun. 24, 1994
Ahmad N Ishaque, Albany, NY (US);
General Electric Company, Schenectady, NY (US);
Abstract
A large area deep-diffused phototransistor having a photosensitive area of at least 1 mm.sup.2, and typically 25 mm.sup.2 or larger includes a light entry layer of a deep-diffused p type semiconductor material; at least one well of an n type semiconductor material that is disposed in contact with the light entry layer so as to form a first p-n junction therebetween; and a respective readout contact comprising a p type semiconductor material that is disposed in the n type well so as to form a second p-n junction. The p type material light entry layer, the n type material well, and the p type material readout contact respectively comprises the collector, base and emitter of the phototransistor. The concentration of the p type dopant in the deep diffused light entry layer has a positive gradient extending from the first p-n junction towards the surface of the light entry layer such that the concentration of the p type dopant is greater the closer the proximity to that surface. The base width of the well is selected such that capacitance of the device is in the range between 0.5 pf/mm.sup.2 and 2 pf/mm.sup.2, whereby the phototransistor provides a desired frequency response up to several GHz.