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-resistance contacts on Ga0.5In0.5P/GaInAs/GaAs pseudomorphic high electron mobility transistor (HEMT) structures. Surfaces prepared by hydrogen radical beam irradiation exhibited better electrical and morphological properties than those cleaned by an HCI/H2 gas mixture. After preparing the surface, an n+-GaAs layer was selectively grown at the drain and source areas. A pseudomorphic HEMT, with a 0.3 mum gate length, had a contact resistance of 0.5 OMEGA mm, an extrinsic transconductance of 400 mS/mm and a cutoff frequency of 55 GHz.