Engineering the electronic defect bands at the Si_1-xGe_x/IL interface: Approaching the intrinsic carrier transport in compressively-strained Si_1-xGe_x pFETs

Abstract

We identify the existence of electronic defect levels close to the Si1-xGex band edges associated with the Ge surface concentration at the Si1-xGex/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 Si1-xGex/IL interface, through control of the Ge surface concentration, high channel carrier mobility over wide charge densities in compressively-strained Si1-xGex channel pFETs is demonstrated. For the first time, the dominant scattering mechanisms for hole mobility in Si1-xGex channel pFETs are investigated to understand the carrier transport physics.