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

The beta-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 beta-Ga2O3 film and c-plane sapphire was confirmed. The beta-Ga2O3 film is ((2) over bar 01) preferred orientation and beta-Ga2O3 < 102 > and < 010 > directions are parallel to Al2O3 < 1 (1) over bar0 > and < 110 >, respectively. Meanwhile, the Bragg diffraction angles of beta-Ga2O3 ((2) over bar 01), ((4) over bar 01), (111) and ((1) over bar 11) planes are carefully measured. Using interplanar spacing equation and Bragg equation, the actual beta-Ga2O3 lattice constants were calculated. The results show that lattice constants b and angle b become larger, but the constant a, c becomes smaller. This suggests that it is difficult to growth high quality beta-Ga2O3 film with just one type of beta-Ga2O3 crystal grains on the Al2O3 substrate due to the mismatch of crystal structure and lattice constants.