HIGH-TRANSCONDUCTANCE DELTA-DOPED INAS ALSB HFETS WITH ULTRATHIN SILICON-DOPED INAS QUANTUM-WELL DONOR LAYER/

Modulation-doping of InAs/AlSb quantum wells generally requires the us e of chalcogenide donor impurities because silicon, the usual donor of choice in MBE, displays an amphoteric behavior in antimonide compound s, In this letter, we demonstrate the use of an ultrathin 9 Angstrom s ilicon-doped InAs well to delta-dope the current-carrying InAs channel of an InAs/AlSb heterostructure field-effect transistor (HFET), Using this new approach, we have fabricated delta-doped 0.6-mu m gate InAs/ AlSb HFET's with a measured extrinsic transconductance of 800 mS/mm at V-DS = 0.8 V, a cutoff frequency f(T) = 60 GHz (f(MAX) = 87 GHz), and well-behaved I-V curves, HFET's with a 2-mu m gatelength also feature very high transconductances in the 700-800 mS/mm range at V-DS = 1.5 V, The present work eliminates the requirement for chalcogenide compou nd donor sources to delta-dope InAs/AlSb quantum wells by allowing the use of silicon in the fabrication of high-performance InAs/AlSb HFET' s.