A Burstein-Moss shift has been observed in highly transparent conducting zinc oxide films prepared by ion-bean-assisted reactive deposition. The optical gaps ranged from 3.27 to 4.1 eV increase with an increase in film conductivities and carrier concentrations. Annealing over 773K reduces conductivities by several orders of magnitude and subsequently narrows the optical gaps from 3.41 to 3.24 eV. When the films are irradiated with a UV light, they exhibit some photoresponse. The observed UV photoresponse can bi interpreted using oxygen photodesorption and chemisorption at the surface