Pressure dependence of Raman linewidth in semiconductors

The pressure dependences of the phonon lifetimes of zone-center optical pho nons of various group IV and III-V semiconductors are calculated from first principles using third-order density-functional perturbation theory. The m icroscopic mechanism responsible, i.e. the anharmonic decay of a phonon int o phonons of different energy, is revealed and the sensitive dependence on pressure is studied in detail. The results are compared with recent measure ments of the pressure dependence of the linewidths of the first order Raman lines of Si,Ge, and SiC.