2-LO-PHONON RESONANT RAMAN-SCATTERING IN II-VI SEMICONDUCTORS

Recently, absolute values of second-order Raman scattering efficiency have been measured around the E(0) and E(0)+Delta(0) critical points o f several II-VI semiconductor compounds. The measurements were perform ed in the z(x,x)(z) over bar backscattering configuration on (001) (Zn Se and ZnTe) and (1(1) over bar0$) (CdTe) surfaces. They show strong i ncoming and outgoing resonances around the band gap and larger scatter ing efficiencies as compared to III-V compounds. A theoretical model w hich includes excitons as intermediate states in the Raman process is shown to give a very good quantitative agreement between theory and ex periment. Only a small discrepancy exists, while in III-V compounds th e discrepancies were close to one order of magnitude. A discussion of the differences in the scattering efficiencies between II-VI and III-V compounds is also reported.