DC and RF performance of 0.25 μm p-type SiGe MODFET

The DC and RF performance of a 0.25 μm gate-length p-type SiGe modulation-doped field-effect transistor (MODFET) is reported. The hole channel consists of compressively strained Si/sub 0.3/Ge/sub 0.7/ layer grown on a relaxed Si/sub 0.7/Ge/sub 0.3/ buffer on a Si substrate. The combination of high-hole mobility, low-gate leakage current, and improved ohmic contact metallization results in an enhancement of the DC and RF performance. A maximum extrinsic transconductance (g(m/sub e/xt)) of 230 mS/mm was measured. A unity current gain cut-off frequency (fT) of 24 GHz and a maximum frequency of oscillation (fmax) of 37 GHz were obtained for these devices.