Performances of laser-processed HEMTs with AlAs-nGaAs superlattice donor layers

The in-site laser desorption of GaAs semi-insulating substrate surfaces prior to MBE (molecular-beam epitaxy) growth and laser processing of ohmic contacts have been used for the fabrication of X-band HEMTs (high-electron-mobility transistors) with superlattice donor layers. The improvements made lead to high-performance devices. The authors discuss details of device fabrication and present electrical characterizations (static measurements and physical investigations, and microwave measurements). In addition, a reliability study indicates that reliability levels comparable to those of GaAs MESFETs are reached. >