Characteristics of Zinc-Oxide-Sulfide-Mixed Films Deposited by Using Atomic Layer Deposition

Abstract

Mixed thin films of ZnO and ZnS were deposited by using atomic layer deposition (ALD) to achieve film properties for active channel materials of transparent electronic devices and the characteristics of ZnO, ZnS and their mixed films with various composition ratios were examined. The chemical bond states of mixed films consisting of ZnO and ZnS phases were analyzed and no sulfate or sulfite phases were observed. The structures of the ZnO and the ZnS films exhibited wurtzite hexagonal crystalline structures. However, the mixed films did not show any specific preferred orientation;, the amorphous character of the mixed films was due to the large lattice mismatch between the ZnO and the ZnS films. The ZnO thin film showed a low resistivity with a higher carrier concentration (up to similar to 10(19) Cm-3) than the ZnS thin film which showed similar to 10(12) cm(-3) carrier concentration. The mixed films exhibited carrier concentrations of 10(15) - 10(18) cm(-3) and a resistivity range of 102 -10(3) Omega.cm, depending on the composition. Furthermore, no significant changes in the electrical properties of the mixed films were observed with respect to the post-heat treatments.