Effect of O2 partial pressure and substrate temperature on the plasma emission spectra and ZnO growth behavior



An on-line measurement of optical emission spectrum (OES) was used to study the variation of Zn and O components in the plasma of ZnO film growth with reactive radio-frequency magnetron sputtering method. It was found that the decline of all the Zn emission lines shows three different stages with the increase of oxygen partial pressure (PO), corresponding to metal sputtering (PO < 6.0 × 10–3 Pa), the compound sputtering (PO > 5.0 × 10–2 Pa), and the transition range (6.0 × 10–3 Pa to 5.0 × 10–2 Pa), respectively. In the stage of compound sputtering, a critical oxygen pressure is found at about 1.5 × 10–1 Pa. At the oxygen pressures below and above the critical pressure, the film growth is found to be O-controlled and Zn-controlled, respectively. Similarly, a critical substrate temperature is found at about 550 °C. At the temperatures above the critical temperature, the variation of Zn472.6 intensity is more obvious, suggesting the deposited films is more close to the stoichiometric ratio than the films deposited at the lower temperatures. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)