ZnO as Transparent Conducting Oxide by Atomic Layer Deposition

Zinc Oxide (ZnO) films were deposited on SiO2/Si and glass substrates by Atomic Layer Deposition using Diethylzinc (DEZ) as the metal precursor and Water (H2O) as the oxidant over a temperature range of 75 degrees C to 225 degrees C. Here we demonstrated self limiting behavior of the Atomic Layer Deposition and the linear growth of the deposited films by in-situ quartz crystal microbalance (QCM) study. The maximum growth rate was found to be similar to 1.8 to 2 angstrom per ALD cycle. The as deposited crystalline ZnO films were found to be c-axis preferentially oriented with dense microstructures, homogeneous grain sizes and low surface roughness. We developed ZnO as similar to 80% transparent conductor with carrier density ca. 10(21) cm(-3) and a controllable resistivity from the intrinsic level (highly insulating) to 10(-3) Omega-cm without any intentional doping.