Hot-electron-injection and resonant-tunneling heterojunction devices.

This article will appear in a volume entitled "Heterojunctions: a Modern View of Band Discontinuities and Device Applications", edited by F. Capasso and G. Margaritondo, to be published by North Holland. A number of heterojunction device concepts are reviewed with the emphasis on their potential for applications and the limitations. The discussion includes charge-injection devices, i.e., those in which hot electrons are transported either ballistically or thermionically between adjacent layers, as well as resonant-tunneling diodes and transistors.