Simulation of electron transport in strained silicon on relaxed Si 1-xGex substrates

The physics of electron transport in pseudomorphically grown Si on relaxed (001) Si_1-xGe_x is explored using an efficient fitted-band Monte Carlo (MC) simulator. The MC simulator is based on a multiband analytical model representing the features of a realistic energy bandstructure. The scattering rates are calculated using a nonlocal pseudopotential bandstructure. The scattering mechanisms included here are: acoustic-phonon scattering, optical phonon scattering, ionized impurity scattering, and carrier-carrier scattering. The impact ionization rate is calculated using an anisotropic energy threshold model. The investigation includes the study of and high field electron transport characteristics at 77 K and 300 K. The mobility enhancement in strained-Si is attributed to both the suppression of intervalley scattering and the lower effective mass transport (due to the lifting of six fold degeneracy of the conduction band minima of silicon). Agreement between calculated and experimental low field mobility has also been shown