Effects of in-situ molecular oxygen exposure on the modulation of electrical properties of zinc oxide thin films grown by atomic layer deposition

The possibility of employing molecular oxygen (O₂) for reducing the carrier concentration of zinc oxide (ZnO) thin films grown by atomic layer deposition was investigated. The exposure of O₂ after the oxygen-source pulse (deionised water) was eventually highly effective for decreasing the carrier concentration over 3-4 orders of magnitude. In contrast, the O₂ pulse, when following the zinc source pulse (diethylzinc), had a minimal effect on the electrical property. Detailed structural, chemical and electrical analyses of the oxygen-modulated ZnO thin films were conducted. Successful electrical modulation of the ZnO thin films was further demonstrated by fabricating back-gated thin film transistors. The improvement in the on-tooff current ratio of the transistors was achieved by the proper exposure of O2.