Exploration of SiGe/Si heterostructure interface in SiGe-channel MOSFETs

Electrical quality of SiGe/Si heterostructure interface in SiGe-channel pMOSFETs is experimentally investigated by low frequency noise measurements and charge pumping measurements, using pMOSFETs with a relatively wide range of Ge fraction x=0.2, 0.5, 0.7, and SiGe thickness d_SiGe of 2-14 nm. It is shown that the low frequency noise in SiGe pMOSFETs can be lower than that in conventional Si pMOSFETs,, and that the noise power at bias conditions showing the maximum transconductance g_mMAX reflect the trap density at the SiGe/Si heterostructure interface, and correspond well to g_mMAX behavior as functions of Ge fraction and d_SiGe. Moreover, it is shown that interface traps in the SiGe/Si heterostructure can be directly evaluated using the charge pumping technique