The lattice distortion of β-Ga₂O₃ film grown on c-plane sapphire

Abstract

The β-Ga₂O₃ film is grown on c-plane sapphire (Al₂O₃) substrate using metal organic chemical deposition method. According to high resolution X-ray diffraction measurement results, the epitaxial relationship between β-Ga₂O₃ film and c-plane sapphire was confirmed. The β-Ga₂O₃ film is ($\overline{2} 01$) preferred orientation and β-Ga₂O₃ 〈102〉 and 〈010〉 directions are parallel to Al₂O₃ 〈$1\overline{1} 0$〉 and 〈110〉, respectively. Meanwhile, the Bragg diffraction angles of β-Ga₂O₃ ($\overline{2} 01$), ($\overline{4} 01$), (111) and ($\overline{1} 11$) planes are carefully measured. Using interplanar spacing equation and Bragg equation, the actual β-Ga₂O₃ lattice constants were calculated. The results show that lattice constants b and angle β become larger, but the constant a, c becomes smaller. This suggests that it is difficult to growth high quality β-Ga₂O₃ film with just one type of β-Ga₂O₃ crystal grains on the Al₂O₃ substrate due to the mismatch of crystal structure and lattice constants.