Physical and materials limitations on burnout voltage of GaAs power MESFET's

This paper presents a study of factors limiting the burnout voltage of GaAs power MESFET's. A new device geometry had been investigated. Novel techniques using electron-beam induced current (EBIC) in the drain loop in a scanning electron microscope (SEM) and the shift in carbon Auger line in a scanning Auger microscope (SAM) have been applied to study the bulk electric field distribution and the surface voltage distribution. These techniques have been used to identify the regions of high electric field that lead to device burnout. The highest burnout voltages were observed at 8 × 10
¹⁶
-cm
^-3
doping with at least 60-V burnout at full channel current and 85 V near pinchoff conditions. This is a new state of the art. An optimum undoped buffer-layer thickness is observed to be compatible with high burnout voltage and low leakage current. Finally, under optimized conditions of doping and geometry, no improvement is observed in the burnout voltage with the use of a higher doped contact layer.