First Stacked Ge0.88Sn0.12 pGAAFETs with Cap, LG=4Onm, Compressive Strain of 3.3, and High S/D Doping by CVD Epitaxy Featuring Record ION of 58μA at VOV=VDS= -0.5V, Record Gm,max of 172μS at VDS

摘要

Record [Sn]=12% and record compressive strain of 3.3% among GeSn 3D transistors to enhance the ION are demonstrated by CVD epitaxy. For the first time, in-situ Ge_0.95Sn_0.05 caps are grown on stacked Ge_0.88Sn_0.12 channels to improve interface quality and separate carriers from the interface to achieve high mobility. L_G is scaled down to 40nm to further boost the ION. Low channel doping and high S/D doping ([B]_peak~1E21cm^{-3) can suppress the impurity scattering in the channels and reduce the contact resistivity for the S/D, respectively, to reveal the intrinsic merit of the high mobility of GeSn. The stacked 3 Ge_0.88Sn_0.12 nanosheets achieve record ION of 58μA at V_OV=V_DS= -0.5V and record G_m,max of 172μS at V_DS= -0.5V among GeSn pFETs, and the performance is comparable to mature Si FinFETs, stacked Si channels, and stacked Ge channels. The caps as barriers on the Ge_0.88Sn_0.12 channels decrease the low frequency noise by reducing trapping/detrapping between the GeSn channels and the gate dielectrics.}