High Field Transport of Hot Electrons in Strained Si/SiGe Heterostructure.

Monte Carlo simulation of two-dimensional electron gas in strained Si/SiGe heterostructures has been carried out to investigate the high electric field transport phenomena. In the Monte Carlo simulation we take into account the intervalley scattering due to the f-type phonons between twofold and fourfold valleys of Si well layer split by the tensile strain in addition to the g-phonon scattering. We obtained the electron drift velocity at room temperature of as high as 1×107 cm/s at 10 kV/cm. Calculated results at 4.2 and 77 K show negative differential mobility beyond 10 kV/cm. At 77 K, transient response of the drift velocity shows a marked overshoot reaching about 3×107 cm/s at 0.2 ps and 10 kV/cm. Ohmic mobility calculated using self-consistent wave functions is also demonstrated. Results are given for the strained Si well width of 10 nm. Obtained low field electron mobility at high temperatures shows a good agreement with the experimental results reported so far.