Rapid epitaxy of 2-inch and high-quality α-Ga<sub>2</sub>O<sub>3</sub> films by mist-CVD method
Xiaojie Wang, Wenxiang Mu, Jiahui Xie, Jinteng Zhang, Yang Li, Zhitai Jia, Xutang Tao
Abstract
Abstract High thickness uniformity and large-scale films of α -Ga 2 O 3 are crucial factors for the development of power devices. In this work, a high-quality 2-inch α -Ga 2 O 3 epitaxial film on c -plane sapphire substrates was prepared by the mist-CVD method. The growth rate and phase control mechanisms were systematically investigated. The growth rate of the α -Ga 2 O 3 films was limited by the evaporation of the microdroplets containing gallium acetylacetonate. By adjusting the substrate position ( z ) from 80 to 50 mm, the growth rate was increased from 307 nm/h to 1.45 μ m/h when the growth temperature was fixed at 520 °C. When the growth temperature exceeded 560 °C, ε -Ga 2 O 3 was observed to form at the edges of 2-inch sapphire substrate. Phase control was achieved by adjusting the growth temperature. When the growth temperature was 540 °C and the substrate position was 50 mm, the full-width at half maximum (FWHM) of the rocking curves for the (0006) and (10-14) planes were 0.023° and 1.17°. The screw and edge dislocations were 2.3 × 10 6 and 3.9 × 10 10 cm -2 , respectively. Furthermore, the bandgaps and optical transmittance of α -Ga 2 O 3 films grown under different conditions were characterized utilizing UV-visible and near-IR scanning spectra.