Growth and characterization of β-Ga<sub>2</sub>O<sub>3</sub> thin films grown on off-angled Al<sub>2</sub>O<sub>3</sub> substrates by metal-organic chemical vapor deposition
Yabao Zhang, Jun Zheng, Peipei Ma, Xueyi Zheng, Zhi Liu, Yuhua Zuo, Chuanbo Li, Buwen Cheng
Abstract
Abstract Beta-gallium oxide ( β -Ga 2 O 3 ) thin films were deposited on c -plane (0001) sapphire substrates with different mis-cut angles along < > by metal-organic chemical vapor deposition (MOCVD). The structural properties and surface morphology of as-grown β -Ga 2 O 3 thin films were investigated in detail. It was found that by using thin buffer layer and mis-cut substrate technology, the full width at half maximum (FWHM) of the ( ) diffraction peak of the β -Ga 2 O 3 film is decreased from 2° on c -plane (0001) Al 2 O 3 substrate to 0.64° on an 8° off-angled c -plane (0001) Al 2 O 3 substrate. The surface root-mean-square (RMS) roughness can also be improved greatly and the value is 1.27 nm for 8° off-angled c -plane (0001) Al 2 O 3 substrate. Room temperature photoluminescence (PL) was observed, which was attributed to the self-trapped excitons formed by oxygen and gallium vacancies in the film. The ultraviolet–blue PL intensity related with oxygen and gallium vacancies is decreased with the increasing mis-cut angle, which is in agreement with the improved crystal quality measured by high resolution X-ray diffraction (HR-XRD). The present results provide a route for growing high quality β -Ga 2 O 3 film on Al 2 O 3 substrate.