Drive current enhancement in high-K/metal gate germanium-carbide pMOSFETs fabricated directly on Si substrates

High-k/metal gate pMOSFETs were fabricated on high-quality Ge_1-xC_x for the first time. Ge_1-xC_x layers with very low RMS roughness of ~3Aring were grown directly on Si by ultra-high-vacuum chemical vapor deposition (UHVCVD), without the use of relaxed Si_1-xGe_x virtual substrates. Ge_1-xC_x buried-channel (BC) and surface-channel (SC) pMOSFETs with EOT = 1.9 nm and L = 10 mum exhibited high drive currents of 10.8 and 15.2 muA/mum, respectively, for V_GS-V_T = -1.0 V. Compared to Si control devices, the BC pMOSFETs showed 2times enhancement in I_Dsat and 1.6times enhancement in the transconductance (G _m). The corresponding enhancements for the SC devices were 3times and 2times, respectively. These results represented an effective hole mobility enhancement of ~1.5times for the BC devices and ~2.5times for the SC devices over the universal curve for Si