Structures and physical properties of films deposited by simultaneous DC sputtering of ZnO and In2O3 or ITO targets

Oxide films in the ZnO-In2O3 and ZnO-tin-doped indium oxide (ITO) systems were deposited by simultaneous de sputtering of ZnO and In2O3 or ITO facing targets at substrate temperatures from room temperature up to 300 degreesC. The ratio delta of the ZnO target current to the sum of both the currents was varied. The bixbyite-type In2O3 phase, an amorphous phase, the homologous ZnkIn2Ok+3 phases, and the wurtzite-type ZnO phase were found in this order with increasing delta values. Characteristic trends were observed for delta -dependent electrical properties within the respective phase groups, regardless of the substrate temperatures. The minimum resistivity of 2.3x10(-4)Omega cm and the maximum carrier concentration of 1.2x10(21) cm(-3) were obtained for the amorphous film deposited at 150 degreesC and delta = 0.20, having the atomic ratio of [Zn]/([In]+[Zn]) = 0.22. Sn doping was effective in improving the electrical properties only in the region where the bixbyite-type In2O3 phase appeared and was less effective in the amorphous, homologous ZnkIn2Ok+3 and wurtzite-type ZnO regions. (C) 2000 Academic Press.