Abstract:

High-mobility Ge p-MOSFETs with relaxed high-quality Ge channel layers directly grown on silicon substrates by surfactant- mediated epitaxy (SME) have been realised. The devices with 30 nm thick LPCVD gate oxides were fabricated with a low-temperature self-aligned W-gate process which is compatible with conventional Si CMOS technology. The influence of a Si cap layer with 0 to 10 11m thickness on top of the Ge channel layer under the gate oxide was investigated yielding a strong increase of saturation transconductance and effective p-channel mobility with decreasing cap layer thickness. For 2 nm Si cap layer devices the intrinsic saturation transconductance reached a maximum of 46 mSlmm (at LG = 1 J.Il1'l) and an effective p-channel mobility value of 31 0 cm21Vs at large gate voltages, which exceeds the mobilities of any pMOSFET fabricated on a silicon substrate