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= -0.5V, and Low Noise

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
0.95
Sn
0.05
caps are grown on stacked Ge0.ssSn0.12 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
0.88
Sn
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 Ge0.ssSn0.12 channels decrease the low frequency noise by reducing trapping/detrapping between the GeSn channels and the gate dielectrics.