MOVPE grown high performance 0.25 μm AlGaAs/InGaAs/GaAs pseudomorphic MODFETs

Abstract We report the growth by MOVPE of Al x Ga 1− x As/In y Ga 1- y As/GaAs strained layer, or pseudomorphic, MODFET structures with x ⩽ 0.28 and y ⩽ 0.20. The metalorganics used were TMGa, TMAl, TMIn; the group V used was arsine at 100% concentration, while silane and disilane were used for doping. Hall measurements on these structures showed 2DEG sheet carrier concentrations up to 2×1012 cm -2 , and excellent room temperature and 77 K mobilities. Devices fabricated from this material with E-beam defined 0.25 μm gate lengths had DC extrinsic transconductances of 300 mS mm -1 . RF testing on wafers up to 40 GHz showed that these MODFETs exhibited good microwave properties, with an extrapolated current gain cut-off frequency ( f T ) of 64 GHz and an estimated maximum frequency of oscillation ( f max ) of 135 GHz.