Influence of buffer thickness on the performance of GaAs field effect transistors prepared by molecular beam epitaxy

The influence of buffer thickness on the performance of GaAs metal semiconductor field effect transistors prepared by molecular beam epitaxy is investigated. Little or no looping or light dependence and good transconductances are obtained for devices with buffer thicknesses of 1 μm and greater. For maximum drain saturation resistance and minimum molecular beam epitaxy growth time, buffer thicknesses of 1 to 1.5 μm are indicated. The dependence of field effect transistor performance, as well as observed backgating effects on buffer thickness are attributed to improvements in the quality of both the buffer and active layers. In addition, preliminary results indicate that the saturation characteristics can be improved and looping reduced if the layers are grown at higher temperatures.