THE MONTE CARLO METHOD APPLIED TO CARRIER TRANSPORT IN Si/SiGe QUANTUM WELLS

Abstract

We present a complete Monte Carlo simulation of the transport properties of a Si/SiGe quantum well. The scattering mechanisms, viz. intervalley phonons, acoustic phonons, interface roughness and impurity scattering (including resonant scattering), are considered in detail, and we derive analytic expressions for the scattering rates, in each case properly taking the quantized electron wave functions into account. The numerically obtained distribution function is used to discuss the influence of each scattering mechanism for different electric fields applied parallel to the interfaces and also different temperatures.

Effect of resonant impurity scattering on the carrier dynamics in Si∕SiGe quantum wells

“…Curves B and D are derived without the resonant state scattering, and they are simular to those presented in Ref. 4. We should mention that curve B broadens to curve D with increasing temperature and/or field strength.…”

“…The first channel which we call conventional Coulomb scattering ͑CCS͒ will be treated as conventional potential scattering, while the second resonant state scattering ͑RSS͒ channel will be analyzed in more details in the next section. As an approximation, which typically is well justified, 4,7 we can ignore the cross term ͑see below͒ and treat the two scattering channels independently.…”

“…In the absence of resonant state scattering, all these phenomena were analyzed in details in Ref. 4. Here we will analyze the influence of resonant state scattering on the distribution function.…”

“…In Si/ SiGe modulation doped structures the Monte Carlo simulation has given useful information on the electron transport properties. [1][2][3][4] The purpose of conventional modulation doping is to increase the carrier mobility by separating the impurity ions from the transport channels. Under this situation, carriers are scattered mainly by phonons and interface roughness.…”