Fabrication and characterisation of double heterojunction In0.48Ga0.52P/In0.20Ca0.80As high electron mobility transistors grown by solid-source molecular beam epitaxy

Double heterojunction (DPI) In0.48Ga0.52P/In0.20Ga0.80As pseudomorphic high electron mobility transistor (p-DHHEMT) structures were grown by solid-sourer molecular beam epitaxy (SSMBE) using a valved phosphorus cracker cell. Maximum drain current (I-DSmax) and transconductance (G(m)) of 370 mA/mm and 360 mS/mm for the 1.25-mu m device, and about 500 mA/mm and 440 mS/mm for the 0.35-mu m device, were measured. The current-voltage (I-V) characteristic shows that possible formation of parasitic channels at the InGaP/GaAs interface could give rise to 'soft' pinch-off behaviour. Cut-off frequency (f(T)) of 12 GHz and maximum oscillation frequency (f(max)) of 33 GHz were achieved for the 1.25-mu m device, and f(T) of 40 GHz and S-max of 130 GHz were measured for the 0.35-mu m device. (C) 1999 Elsevier Science Ltd. All rights reserved.