Engineering the electronic defect bands at the Si1−xGex/IL interface: Approaching the intrinsic carrier transport in compressively-strained Si1−xGex pFETs

We identify the existence of electronic defect levels close to the Si
_1-x
Ge
_x
band edges associated with the Ge surface concentration at the Si
_1-x
Ge
_x
/IL interface (0 <; x <; 0.5). These electronic defects act as carrier scattering centers severely degrading the channel mobility and modulate the device threshold voltage. By successfully eliminating the electronic defects states at the Si
_1-x
Ge
_x
/IL interface, through control of the Ge surface concentration, high channel carrier mobility over wide charge densities in compressively-strained Si
_1-x
Ge
_x
channel pFETs is demonstrated. For the first time, the dominant scattering mechanisms for hole mobility in Si
_1-x
Ge
_x
channel pFETs are investigated to understand the carrier transport physics.