An analytical model for the photodetection mechanisms in high-electron mobility transistors

Abstract

The use of microwave high-electron mobility transistois (HEMT's) as photodetectors or optically controlled circuit elements have attracted interest. A model of the optical characterisl cs of HEMT's, which takes into account carrier transport as we 11 as the quantum mechanical nature of the two-dimensional (2-D) electron gas channel, is presented. It is shown that the effeci of illumination is equivalent to a shift in the gate to source bias voltage, referred to as the internal photovoltaic effect:. The theoretical model is supported by experimental results that demonstrate that the HEMT photoresponse is a nonlinear funcl on of light intensity with very high responsivity at low optical power levels. © 1996 IEEE.