Effective mass for strained p-type Si1−xGex

The density of states and carrier concentration effective masses have been calculated for strained p-type nondegenerate Si1−xGex using the band structure recently proposed by Manku and Nathan (Phys. Rev. B). The results show a significant decrease in both masses compared to pure silicon. It turns out that the total carrier concentration effective mass for a Ge composition, x=0.3 is approximately three times smaller than the corresponding value for silicon. At 300 K, the total carrier concentration effective mass is 0.35 (normalized with the free electron mass) and at 77 K, the corresponding value is 0.22.