BAND-GAP WIDENING OF CDO THIN-FILMS

CdO thin films were deposited on silica glass substrates by rf sputter ing. The orientation of the crystal axis in the films was changed by v arying the sputtering conditions. The (100)-oriented films were anneal ed under various conditions to change the carrier concentration. A blu eshift of the optical absorption edge was observed as the carrier conc entration increased, and band-gap widening was analyzed using the Burs tein-Moss formula. We found that the intrinsic direct-band-gap E-g(0) (Gamma(15)-Gamma(1) gap) and the reduced effective mass m(vc) are 2.2 2+/-0.01 eV and (0.274+/-0.013) m(0), respectively, at room temperatur e. The results are discussed in relation to the band structure of CdO. (C) 1998 American Institute of Physics. [S0021-8979(98)11023-X].