Three-dimensional phonon confinement in CdSe microcrystallites in glass

Results are presented which demonstrate the existence of unambiguous three-dimensional quantum confinement of phonons within crystallites of the II-VI semiconductor CdSe, which were prepared by the method of diffusive growth within a doped glass matrix. The confinement was investigated by means of Raman scattering from zone centre longitudinal optical (LO) phonons. These Raman spectra illustrate LO phonon peaks showing a low-energy shift and broadening with decreasing crystallite size. The experimental measurements are compared with a theoretical model of phonon confinement which includes a size distribution parameter. The experimental results are in good agreement with the predictions of this model. Surface vibrational modes and the effects of hydrostatic pressure from the glass matrix do not appear to be of significance in the samples investigated.