Comparison between ZnO films grown by atomic layer deposition using H2O or O-3 as oxidant

Abstract

This study investigated the atomic layer deposition (ALD) behavior of zinc oxide (ZnO) films on SiO2/Si substrates using Zn(C2H5)(2) and 03 as the precursor and oxidant, respectively, at substrate temperatures ranging from 230 to 300 degrees C, and the electrical properties of the thin films. The self-limiting ALD mechanism of ZnO thin film growth was confirmed in the whole temperature region, and the growth rate decreased from 0.19 nm/cycle at 230 degrees C to 0.16 nm/cycle at 300 degrees C. ZnO films with a c-axis preferential orientation were obtained at these relatively low temperatures. The films contained a lower oxygen concentration compared to the films grown with the same precursor and H2O oxidant. However the ZnO film grown with the 03 oxidant at 300 degrees C showed approximately a resistivity three orders of magnitude higher than that of the ZnO film using the H2O oxidant, due to higher Si impurity concentration in the ZnO films. Si diffusion into the ZnO films must be due to the stronger oxidation power Of 03 compared to H2O. (c) 2004 Elsevier B.V. All rights reserved.