Browse Prior Art Database

Superlattice Hot Electron Transistor

IP.com Disclosure Number: IPCOM000062549D
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Harder, C: AUTHOR [+2]

Abstract

The structure of the proposed device corresponds to that of "normal" hot electron transistors except that the base region is a superlattice consisting of alternating layers of GaAs and AlAs. Carrier injection into the base is either through a tunnel barrier at the emitter or by means of a thermal injector. The hot electrons are injected into the higher one of two subbands of the superlattice and are separated from the other electrons in the base by the superlattice energy gap. Scattering to the lower band is substantially reduced and most injected electrons remain in the higher subband. This results in a significant increase in the lifetime of the injected electrons and thus in increased current gain.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 56% of the total text.

Page 1 of 2

Superlattice Hot Electron Transistor

The structure of the proposed device corresponds to that of "normal" hot electron transistors except that the base region is a superlattice consisting of alternating layers of GaAs and AlAs. Carrier injection into the base is either through a tunnel barrier at the emitter or by means of a thermal injector. The hot electrons are injected into the higher one of two subbands of the superlattice and are separated from the other electrons in the base by the superlattice energy gap. Scattering to the lower band is substantially reduced and most injected electrons remain in the higher subband. This results in a significant increase in the lifetime of the injected electrons and thus in increased current gain. The figure schematically shows an embodiment of the proposed superlattice transistor in which carrier injection into the base is through an emitter-base tunnel barrier. The superlattice consists of alternating layers: one lattice layer AlAs for five GaAs layers. With such superlattice, the Q-minimum (in the energy versus crystal momentum diagram), normally existing in GaAs, exhibits subbands separated by subgaps - for the described superlattice the two first subbands are separated by a gap of 117 meV. In operation, the electrons are injected from the emitter across the emitter-base tunnel barrier into the higher one of the two subbands of the superlattice forming the base. These injected hot electrons have a higher energy than th...