High-transconductance p-type SiGe modulation-doped field-effect transistor

High-transconductance 1.5μm-gate-length p-type modulation-doped field-effect transistors (MODFETs) have been fabricated using standard optical lithography on a high hole-mobility SiGe heterostructure grown by ultrahigh vacuum chemical vapour deposition (UHV-CVD). A maximum DC extrinsic (intrinsic) transconductance of 95mS/mm (138mS/mm) at room temperature has been achieved, which to our knowledge is the highest for p-type field-effect transistors at this gate length. A unity current-gain frequency ft of 2.1 GHz has been measured. The gate leakage current was quite low and was of the order of a few μA/mm. These enhancement-mode devices exhibit reasonable pinch-off characteristics. © 1995, IEE. All rights reserved.