Properties and design theory of ultrafast GaAs metal-semiconductor-metal photodetector with symmetrical Schottky contacts

Abstract

A GaAs metal-semiconductor-metal photodetector fabricated in a symmetrical and interdigital Schottky contact structure on a semi-insulating GaAs substrate is discussed. The device exhibits a high-speed response and a very low dark current, even with a moderate size (200 mu m/sup 2/). Ultrafast responsivity is due to the high drift velocity of the photoelectrons and low capacitance. A design theory for optimum performance which includes a compromise between the circuit time constant and the transit time is described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>