【Domestic Papers】Unraveling evolution of microstructural domains in the heteroepitaxy of β-Ga₂O₃ on sapphire

      Up to now, the heteroepitaxy of β-Ga₂O₃  thin films on sapphire substrates has been extensively studied. The distortion and tilting disorder of β-Ga₂O₃  domains play a key role in the formation of defect, including mismatched dislocations and stacked Stacking Faults, which often act as carrier compensation and scattering centers, worsening carrier transport characteristics and severely degrading device performance. Recently, the research team of Professor Ye Jiandong of Nanjing University has grown β-Ga₂O₃ films with β-(Al_0.57Ga_0.43)₂O₃ buffer layer on sapphire substrate by hydride vapor phase epitaxy method. By adjusting the growth  temperature, the small Angle domain boundary is eliminated, and the quality of β-Ga₂O₃ heterogeneous epitaxy films and the final device performance are improved by minimizing domain disturbance. the related research results are published in Applied Physics as "Unraveling evolution of microstructural domains in the heteroepitaxy of β-Ga₂O₃ on sapphire" Letters.

Abstract:

      Resolving the aberrations of microstructure domains in epitaxial β-Ga₂O₃   is essential for phase engineering and performance improvement, and the evolution of the related β-Ga₂O₃ heteroepitaxial domains remains largely unexplored. In this paper, we use halide vapor phase epitaxy technique to grow β-(Al_0.57Ga_0.43)₂O₃ buffer₃  layer on (0001) sapphire substrate, and quantitatively study the microstructure domains of (-201) oriented epitaxy β-Ga₂O₃ thin films. The X-ray diffraction rocking curves of (-201) β-Ga₂O₃  grown below 950 ℃ shows a significant split, indicating the domain tilt misalignment. Quantitative evaluation by transmission electron microscopy showed that the domain tilt Angle decreased significantly from 2.3° to 0.9° along the [132] region axis and from 2.3° to 0.56° along the [010] region axis when the growth temperature increased from 850 ° to 1100 ° C. This indicates that the elimination of small-angle domain boundaries is energetically advantageous at high temperatures above 1000 ° C. Quantitative studies of domain disorder evolution in β-Ga₂O₃ reveal ways to improve epitaxial quality for applications in leading-edge power electronics and optoelectronic devices.

DOI: 10.1063/5.0191831