Quantum Device Development

Abstract

Abstract : The results of the first year of research on and development of resonant tunneling transistors are described. A true resonant tunneling transistor consists of a single-well, double-barrier resonant tunneling diode structure to which a third terminal, directly contacting the quantum well, has been added. Two types of resonant tunneling transistors (RTT) are included within the scope of the contract: a unipolar version called the Quantum Excited-State Tunneling Transistor (QuESTT), and a pseudomorphic bipolar version called the Bipolar Quantum Resonant Tunneling Transistor (BiQuaRTT). A lattice-matched version of the BiQuaRTT has been developed. The report describes the development of a theory of resonant tunneling structures and its use to derive device models that have been used in the design of device structures. It also describes the extensive process development required to permit contacting the very thin (50 A) quantum well base layers, and also to isolate the emitter, base, and collector layers. The processes developed have been used to fabricate transistors, and these devices have been characterized electrically. The characterization reveals that a pseudomorphic BiQuaRTT that shows transistor action with a current gain of 5 has been fabricated. Achievement of a functional QuESTT is thought to be imminent. Keywords: Semiconductor devices; Gallium arsenide devices; Heterojunction transistors; Resonant tunneling transistors; Quantum semiconductor devices.