title: Sidewall GaAs tunnel junctions fabricated using molecular layer epitaxy.
abstract: In this article we review the fundamental properties and applications of sidewall GaAs tunnel junctions. Heavily impurity-doped GaAs epitaxial layers were prepared using molecular layer epitaxy (MLE), in which intermittent injections of precursors in ultrahigh vacuum were applied, and sidewall tunnel junctions were fabricated using a combination of device mesa wet etching of the GaAs MLE layer and low-temperature area-selective regrowth. The fabricated tunnel junctions on the GaAs sidewall with normal mesa orientation showed a record peak current density of 35 000 A cm-2. They can potentially be used as terahertz devices such as a tunnel injection transit time effect diode or an ideal static induction transistor.
authors.affiliation: Department of Materials Science, Graduate School of Engineering, Tohoku University, Aramaki Aza Aoba 6-6-11-1020, Sendai, 980-8579, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Ohno
authors.affiliation: International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Namiki 1-1, Tsukuba, 305-0044, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Oyama
keywords: Deep level; Impurity doping; Molecular layer epitaxy of gallium arsenide; Quantum-confined tunnelling; Sidewall tunnel junction; Terahertz devices; Thin film