MEASUREMENT OF THE OPTICAL BAND-GAP AND CRYSTAL-FIELD SPLITTING IN WURTZITE CDTE

CdTe nanocrystals embedded in a sodium borosilicate matrix, obtained b y a sol-gel process, present a wurtzite (hexagonal) structure. Low-tem perature photoluminescence and absorption spectra are measured for sam ples containing bulklike nanocrystals large enough to suppress confine ment effects. Thus, the fundamental free-exciton gap and the splitting between the A (Gamma(9)(v) - Gamma(7)(c)) and B (Gamma(7)(v) - Gamma( 7)(c)) excitons of bulk wurtzite CdTe are measured. We find E(g)(A) = 1653 +/- 1 meV and E(g)(A) - E(g)(B) = 46.5 +/- 1.0 meV, which corresp onds to a crystal-field splitting Delta(cr) = 71.6 +/- 1.5 meV.