CHEMICAL BEAM EPITAXY SELECTIVELY-REGROWN N-GAAS LAYER ON METALORGANIC CHEMICAL-VAPOR-DEPOSITION GROWN GAINP()GAINAS/GAAS PSEUDOMORPHIC HIGH-ELECTRON-MOBILITY TRANSISTOR STRUCTURE/

We used selective chemical beam epitaxy (CBE) to fabricate low-resista nce contacts on Ga0.5In0.5P/GaInAs/GaAs pseudomorphic high electron mo bility transistor (HEMT) structures. Surfaces prepared by hydrogen rad ical beam irradiation exhibited better electrical and morphological pr operties than those cleaned by an HCI/H2 gas mixture. After preparing the surface, an n+-GaAs layer was selectively grown at the drain and s ource areas. A pseudomorphic HEMT, with a 0.3 mum gate length, had a c ontact resistance of 0.5 OMEGA mm, an extrinsic transconductance of 40 0 mS/mm and a cutoff frequency of 55 GHz.