Impact ionization rates for strained Si and SiGe

Investigation of the performance of strained-SiGe vertical IMOS-transistors

“…From Fig. 6a, we see that the II coefficients for biaxially strained SiGe (with 20% Ge) are much smaller than for relaxed Si despite the higher II rates in the strained layer which was shown in [38]. This is due to alloy scattering, which reduces the number of electrons at high energies [45].…”

“…However, there are few reports, both theoretical and experimental, about the II rate of strained SiGe. In this work, we use the II rate for biaxially strained SiGe which were presented in [38].…”

“…The calculation approach in [38] follows Fermi's golden rule and the constant matrix element approximation. There are three main points making this calculation reliable: First, the momentum and energy are exactly conserved during the numerical calculation of the six-dimensional integral in k-space over four conduction bands and three valence bands.…”

“…the II rate depends not only on the energy of the initial carrier, but also on its wave vector. This consideration is important for simulating the SSiGe-IMOS because the II rate of strained SiGe is shown to be much more anisotropic than that of relaxed Si in the k-space, especially where the energies of initial carriers are close to the ionization threshold energy [38].…”

Hydrodynamic device simulation of 200 GHz SiGe heterojunction bipolar transistors

“…In [11] the characteristic of impact ionization for uniaxially/biaxially strained Si and biaxially strained SiGe were explored. In [12] a macroscopic energy relaxation time analytical model for HD simulation of SiGe HBTs was derived and compared with MC simulation for 100 GHz SiGe HBTs.…”