Impact ionization coefficients in Si1−xGex

We have measured the electron and hole impact ionization coefficients in Si1−xGex alloys. Carrier multiplication measurements were made on relaxed Si1−xGex/Si diodes grown by gas source molecular beam epitaxy. The hole to electron impact ionization coefficient ratio, β/α, varies from 0.3 to 4 in the composition range of x=0.08–1.0.