GaAs devices and circuits for terahertz applications

GaAs diodes are used as mixer and multiplier elements throughout the terahe rtz frequency range. This is primarily because the technology is well-under stood, convenient to use and supplies adequate performance for most applica tions. GaAs Schottky diodes are the mixer element of choice for terahertz a pplications where the added expense of cryogenic superconductive (SIS) or h ot electron bolometric (HEB) mixers is not warranted. Furthermore, GaAs (an d InP) multiplier diodes, used in conjunction with millimeter wave oscillat ors, are presently the best available technology for generating terahertz p ower from solid-state sources. In this paper, we will first review the stat us of terahertz diode technology with emphasis on the recent results which define the cutting edge of diode performance. We will then discuss the impr ovements that are needed to ensure that this technology not only meets the expanding needs of scientific researchers, but also is extended to future m ilitary and commercial applications. (C) 1999 Elsevier Science B.V. All rig hts reserved.