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:
Aug. 29, 1989
Filed:
Apr. 15, 1987
Hugh I Ralph, Lewes, GB;
U.S. Philips Corp., New York, NY (US);
Abstract
A high mobility p channel semiconductor device (such as a field-effect transistor) is suitable for operation at room temperature, for example in a circuit with an n channel device. Whereas hole modulation doping both in single heterojunction and in heterostructure quantum well devices provides a significant increase in hole mobility only at cryogenic temperatures, the present invention employs less than 5 nm wide and very deep quantum wells (about 0.4 eV and deeper) to reduce the effective mass of 'heavy' conduction holes for motion in the plane of the quantum well. Hole mobilities at 300 degrees K. are obtained in excess of 2.5 times those in bulk material of the same narrow bandgap semiconductor as used for the quantum well. In a particular example such a quantum well is formed of GaAs (or GaInAs) between AlAs barrier layers.