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JOURNAL OF SYNTHETIC CRYSTALS ›› 2022, Vol. 51 ›› Issue (7): 1152-1157.

• Research Articles • Previous Articles     Next Articles

Effect of Growth Pressure on Properties of β-Ga2O3 Thin Films Grown by Molecular Beam Epitaxy

CAI Wenwei1, LIU Xiangwei1, WANG Hao1, WANG Jianyuan1, ZHENG Licheng1, WANG Yongjia1, ZHOU Yinghui1, YANG Xu1,2, LI Jinchai1,2, HUANG Kai1,2, KANG Junyong1   

  1. 1. Engineering Research Center for Micro-Nano Optoelectronic Materials and Devices, Ministry of Education, Fujian Provincial Key Laboratory ofSemiconductor Materials and Applications, CI Center for OSED, Department of Physics, Xiamen University, Xiamen 361005, China;
    2. Tan Kah Kee Innovation Laboratory, Future Display Institue of Xiamen, Xiamen 361005, China
  • Received:2022-04-15 Online:2022-07-15 Published:2022-08-11

Abstract: The effect of growth pressure on the properties of β-Ga2O3 thin films epitaxial on c-plane sapphire substrate with 6° oblique cut angle by plasma-assisted molecular beam epitaxy were systematically studied. All of the epitaxial films present (201) orientated single-crystalline structure with smooth surface morphology. In addition, the crystalline quality and growth rate increase gradually with the increase of the growth pressure, as demonstrated by X-ray diffraction and scanning electron microscopy characterizations. According to the X-ray photoelectron spectroscopy measurement results, the percentage of oxygen vacancy and Ga3+ oxidation states decrease and increase, respectively, with increasing growth pressure, resulting in the increment of atomic ratio of O to Ga. Moreover, through the calculation of Tauc frormula and Urbach tail model, the results show that the optical band gap of the films increase from 4.94 eV to 5.00 eV, while Urbach energy decreases from 0.47 eV to 0.32 eV. These results suggest that the crystal quality and optical property of β-Ga2O3 were improved by increasing the growth pressure.

Key words: β-Ga2O3 thin film, molecular beam epitaxy, growth pressure, defect density, crystal quality, optical property

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