High-f T n-MODFETs Fabricated on Si/SiGe Heterostructures Grown by UHV-CVD

We present high-frequency results of n-channel MODFETs fabricated on high-mobility Si/SiGe strained layer heterostructures grown by ultrahigh vacuum chemical vapor deposition (UHV-CVD). Devices with gate length L_g = 0.2 µm and drain source separation L_ds = 0.9 µm displayed unity current gain cutoff frequencies as high as f_T = 45 GHz (47 GHz) at V_ds=+0.6 V (+1.5V). Similar devices with L_g = 0.2 µm and L_ds=0.5 µm produced values of f_T = 61 GHz (62 GHz) at V_ds = +0.6V (+1.0V). The value f_T = 62 GHz is the highest unity current gain cutoff frequency reported to date for an n-channel strained Si MODFET.