Wide band gap $p$-type semiconductors Cu$_{3}$TaQ$_{4}$ (Q = S or Se)*

The structural and optical properties of thin films, powders, and single crystals of two wide band gap ($E_{g} \quad >$ 2.4 eV) $p$-type semiconducting materials Cu$_{3}$TaQ$_{4}$ (Q = S, Se) are presented. These materials exhibit a cubic crystal structure, which is a favorable processing characteristic and unusual among Cu-based wide-gap $p$-type materials. Thin films have been prepared using a two-step growth process involving pulsed laser deposition of ceramic Cu$_{3}$TaQ$_{4}$ targets and \textit{ex-situ} annealing of the as-deposited films in a chalcogenide-containing atmosphere. The resultant films exhibit mixed polycrystalline and (100)-oriented structure when grown on amorphous SiO$_{2}$ substrates and show strong (100) preferential orientation when prepared on single-crystal yttria-stabilized zirconia substrates. Powders and thin films of Cu$_{3}$TaS$_{4}$ exhibit intense visible photoemission when irradiated by UV light, and the wavelength of the photoemission can be modulated by doping.