HIGH-TRANSCONDUCTANCE P-TYPE SIGE MODULATION-DOPED FIELD-EFFECT TRANSISTOR

High-transconductance 1.5 mu m-gate-length p-type modulation-doped fie ld-effect transistors (MODFETs) have been fabricated using standard op tical lithography on a high hole-mobility SiGe heterostructure grown b y ultrahigh vacuum chemical vapour deposition (UHV-CVD). A maximum DC extrinsic (intrinsic) transconductance of 95mS/mm (138mS/mm) at room t emperature has been achieved, which to our knowledge is the highest fo r p-type field-effect transistors at this gate length. A unity current -gain frequency f(t) of 2.1GHz has been measured. The gate leakage cur rent was quite low and was of the order of a few mu A/mm. These enhanc ement-mode devices exhibit reasonable pinch-off characteristics.