Alloy and phonon scattering limited hole lifetimes in Si/SiGe heterostructures

The alloy disorder and phonon scattering intersubband relaxation rates of holes in SiGe quantum wells have been calculated using the 6×6 k·p method. The relative importance of different branches of non-polar optical and acoustic phonons is discussed, and compared with the alloy disorder contribution. Generally, for low-energy transitions at lower temperatures, the alloy scattering is found to be the dominant relaxation mechanism. The results are relevant for the design of SiGe based quantum cascade lasers operating via valence intersubband transitions.