James P Eisenstein, 721852 Monterey Rd, South Pasadena, CA 91030

5241190, Aug 31, 1993

Oct 17, 1991

7/779429

James P. Eisenstein - Summit NJ
Loren N. Pfeiffer - Morristown NJ

AT&T Bell Laboratories - Murray Hill NJ

H01L 2906
H01L 31072

257 24

Quantum wells are typically formed in a semiconductor body comprising alternating barrier layers and quantum well layers. A longitudinal dimension can be defined along the layers, and the body has a pair of surfaces on opposite sides of the set of layers. In accordance with the invention, apparatus for contacting a plurality of layers within the semiconductor body comprises a first contact for contacting a plurality of wells at a first position and a second contact for contacting the wells at a second position longitudinally spaced apart from the first contact. A first electrode overlies and extends across the wells on one surface at a longitudinal position intermediate the two contacts, and second electrode on the opposite surface overlies and extends across the wells intermediate the contacts. By applying appropriate voltages to the electrodes, one or more of the underlying quantum wells can be selectively depleted locally of carriers, thereby controlling which of the wells can conduct between the contacts. This arrangement permits fabrication of a variety of new switching devices and transistors.