Influence of Mutual Drag of Light and Heavy Holes on conductivity of p-Silicon and p-Germanium

Conductivity of p-Si and p-Ge is considered for two band model with due regard for mutual drag of light and heavy holes. It is shown that for small and moderate temperatures this drag significantly diminishes drift velocity of light holes and, as result, the total conductivity of crystal. Considered here drag-effect appears as well in the form of nonmonotonous dependences of conductivity on temperature and carrier density.