Effect of Temperature on the Structural and Optical Properties of Ga2O3Thin Films Grown on m-plane Sapphire Substrates by Low-Pressure MOCVD

In this paper, Ga2O3 films were grown on m-sapphire substances at different temperatures of 600 °C, 700 °C and 800 °C by low pressure MOCVD. By changing the temperature, the crystal phase change of the Ga2O3 thin films grown on the m-sapphire substrates were studied. The effects of temperature on structural characteristics, surface morphology and optical properties of the films were studied systematically. XRD results indicated that the mixture of α-phase and β-phase Ga2O3 films were obtained on the m-sapphire substrates. As the temperature increased to 800 °C, the growth of α-Ga2O3 was weakened. The degree of polycrystallization of β-Ga2O3 decreased, and it gradually changed to preferential growth along the (−402) direction. With increasing of the temperature, the surface morphology of films was obviously changed. AFM measurement showed that the growth temperature has an important effect on the formation of Ga2O3 grains. As the temperature increased, the grain size of the film gradually increased. The analysis results of Raman spectroscopy detected the Raman vibration modes of α-Ga2O3 and β-Ga2O3. In addition, the photoluminescence properties of Ga2O3 thin films have also been systematically studied. Compared with c-sapphire, Ga2O3 thin films grown on m-sapphire substrates have more photoluminescence peaks, and the photoluminescence intensity increased with increasing temperature.