MOVPE GROWN HIGH-PERFORMANCE 0.25 MU-M ALGAAS/INGAAS/GAAS PSEUDOMORPHIC MODFETS

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 less-than-or-equal-to 0.28 and y less-than-or-equal-to 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 x 1012 cm-2, and excellent room temperature and 77 K mobilities. Devices fabricated from this material with E-beam defined 0.25-mu-m 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.