Raman scattering in II-VI semiconductor alloys and superlattices

Raman scattering is a powerful tool for the investigation of II-VI compounds. In particular, scattering by longitudinal optical (LO) phonons shows very strong resonances associated with the increased ionicity and reduced screening in these materials as compared with III-V and group IV semiconductors. In alloys of II-VI compounds, resonance Raman scattering by LO phonons can be used for electronic band structure studies, including the determination of critical points and their broadening. More recently, the fabrication of II-VI superlattices has received much attention. These systems, which range from narrow gap superlattices to wide gap structures, cover an impressive range of possible technological applications. They pose new problems such as interdiffusion, strain distribution, band offsets, interband transition energies, etc. Raman scattering can be used to address all these questions. In this paper, I illustrate the applications of Raman scattering by reviewing resonance experiments on HgCdTe alloys and more recent Raman work on CdTe-ZnTe superlattices.