Effect of o ₂ 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 (P _O), corresponding to metal sputtering (P _O < 6.0 × 10 ^-3 Pa), the compound sputtering (P _O > 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 Zn _472.6 intensity is more obvious, suggesting the deposited films is more close to the stoichiometric ratio than the films deposited at the lower temperatures.