Temperature dependence of indium nitride oxidation properties

The oxidation of InN and In-rich InN films grown on (0001) sapphires by low-pressure MOCVD has been investigated. X-ray diffraction (XRD) measurements show that stoichiometric InN is difficult to be oxidized at the temperature lower than 400°C. However, nonstoichiometric In-rich InN can be oxidized at low temperature even as low as 300°C. And In-rich InN films are fully oxidized at 450°C. According to the scanning electron microscope (SEM) images, the oxidization of metal In grains on the surface of In-rich InN film is the main process at the temperature lower than 400°C. Above 400°C, metal In and InN begin to be oxidized simultaneously, which also indicates that stoichiometric InN is difficult to be oxidized at the temperature less than 400°C.