N-CHANNEL ALSB GASB MODULATION-DOPED FIELD-EFFECT TRANSISTORS/

We report the first fabrication of a GaSb n-channel modulation-doped f ield-effect transistor (MODFET) grown by molecular beam epitaxy. The m odulation-doped structure exhibits a room temperature Hall mobility of 3140 cm(2) V-1 s(-1) and 77 K value of 16000 cm(2) V-1 s(-1), with co rresponding sheet carrier densities of 1.3 x 10(12) cm(-2) and 1.2 x 1 0(12) cm(-2). Devices with 1 mu m gate length yield transconductances of 180 mS mm(-1) and output of 5 mS mm(-1) at 85 K. The device charact eristics indicate that electron transport in the channel occurs Primar ily via the L-valley of GaSb above 85 K. The effective electron satura tion velocity is estimated to be 0.9 x 10(7) cm s(-1). Calculations sh ow that a complementary circuit consisting of GaSb n- and p-channel MO DFETs can provide at least two times improvement in performance over A lGaAs/GaAs complementary circuits. (C) 1997 Elsevier Science Ltd.