An accurate calculation of the d.c. electrical and thermal characteristics of GaAs transferred-electron devices

Abstract

A physical model to simulate the d.c. behaviour of GaAs transferred-electron devices has been developed. An accurate calculation of the electrical and thermal characteristics is made possible by solving the semiconductor device equations self-consistently with the heat flow equation. A novel heat flow analysis has been developed to model non-uniform heat generation/absorption across the whole GaAs region including high-low junctions, substrates, buffer and contact regions. Since a thermal current term is included in the current density equation, commonly consisting of drift and diffusion terms only, the analysis is referred to as a drift-diffusion-thermal model. The model is shown to be useful for the thermal design of transferred-electron devices for operation in CW transferred-electron oscillators. In addition to the design of the heat sink configuration, the doping concentration profile of the GaAs region can also be designed to reduce operating temperatures, thereby ensuring improved d.c. microwave conversion efficiency and lifetime.