HIGH-FIELD ELECTRON-TRANSPORT IN SIGE ALLOY

Electron transport in unstrained Si1-xGex (0 less-than-or-equal-to x l ess-than-or-equal-to 0.4) alloy is studied in the present work using t he Monte Carlo (MC) simulation technique. Electron transport character istics (drift velocity, impact ionization (II) coefficient, etc.) are evaluated over a wide range of electric fields. It is found that not o nly low-field mobility but also saturation velocity and impact ionizat ion coefficients are reduced with increasing Ge fraction due to alloy scattering. More importantly, the high-energy (epsilon > 2 eV) electro n population is reduced to a much greater extent than the ionization c oefficient. Simple analytical expressions for electron low-field mobil ity, saturation velocity and II coefficient which can be easily implem ented in device simulation programs are proposed.