Impact ionization rates for strained Si and SiGe

With the constant-matrix-element approach we have calculated the impact ionization (II) rates for uniaxially/biaxially strained Si and biaxially strained SiGe. Energy and momentum are exactly conserved during the calculation of the six-dimensional integral in k-space over four conduction and three valence bands. The wave-vector space is discretized with a very fine grid with a spacing of up to 140(2π/a), where a is the lattice constant. II coefficient and quantum yield for relaxed Si, strained Si and strained SiGe are calculated through full-band Monte Carlo simulations. Good agreement between simulation and experimental data for relaxed Si is obtained.