Highly Polarization-Deep-Ultraviolet-Sensitive ß-Ga2O3 Epitaxial Films by Disrupting Rotational Symmetry and Encrypted Solar-Blind Optical Communication Application.

Ultrawide bandgap semiconductor ß-Ga2O3 (4.9 eV), with its monoclinic crystal structure, exhibits distinct anisotropic characteristics both optically and electrically, making it an ideal material for solar-blind polarization photodetectors. In this work, ß-Ga2O3 epitaxial films were deposited on sapphire substrates with different orientations, and the mechanisms underlying the anisotropy of these epitaxial films were investigated. Compared to c-plane sapphire, the lattice mismatch between m- or r-plane sapphire and ß-Ga2O3 is more pronounced, disrupting the rotational symmetry of the films and rendering them anisotropic. Thanks to the improved anisotropy, the polarization ratio of the photodetector based on ß-Ga2O3 films grown on r-plane substrates is 0.24, nearly ten times higher than that on c-plane substrates. Finally, by utilizing these polarization-sensitive photodetectors, we developed an encrypted solar-blind ultraviolet optical communication system. Our work provides a new approach to facilitate the fabrication and application of high-performance polarization-sensitive solar-blind photodetectors.

Bandgap Engineering and Oxygen Vacancy Defect Electroactivity Inhibition in Highly Crystalline N-Alloyed Ga2O3 Films through Plasma-Enhanced Technology.

Previous research has shown that the hybridization of N 2p and O 2p orbitals effectively suppresses the electrical activity of oxygen vacancies in oxide semiconductors. However, achieving N-alloyed Ga2O3 films, known as GaON, poses a significant challenge due to nitrogen's limited solubility in the material. In this study, a new method utilizing plasma-enhanced chemical vapor deposition with high-energy nitrogen plasma was explored to enhance the nitrogen solubility in the material. By adjusting the N2 and O2 carrier gas ratio, we could tune the thin film's bandgap from 4.64 to 3.25 eV, leading to a reduction in the oxygen vacancy density from 32.89% to 19.87%. GaON-based photodetectors exhibited superior performance compared to that of Ga2O3-based devices, with a lower dark current and a faster photoresponse speed. This investigation presents an innovative approach to achieving high-performance devices based on Ga2O3.