【Member Papers】 Xidian University --- Improved crystal quality of β-Ga₂O₃ on sapphire (0001) substrates by induced-nucleation technique and enhancement of Ga₂O₃ UV photodetectors performance

      Researchers from the Xidian University have published a dissertation titled "Improved crystal quality of β-Ga₂O₃ on sapphire (0001) substrates by induced-nucleation technique and enhancement of Ga₂O₃ UV photodetectors performance" in Journal of Alloys and Compounds.

Acknowledgements

      This work was supported by the National Key R&D Program of China (Grant No. 2022YFB3604400), National Science Fund for Distinguished Young Scholars (Grant No. 61925404), National Natural Science Foundation of China (Grant No. 62104185, 62074120, 62404167), Postdoctoral Fellowship Program of CPSF (Grant No. GZC20241306), and Natural Science Basic Research Program of Shaanxi Province (Grant No. 2023-JC-JQ-56).

Background

      Due to its ultra-wide bandgap, high critical breakdown electric field, and high Baliga’s figure-of-merit, β-gallium oxide (β-Ga₂O₃) has attracted significant attention. As the most thermodynamically stable polymorph of Ga₂O₃, β-Ga₂O₃ shows great potential for advanced electronic and power applications. Various β-Ga₂O₃-based devices, including Schottky barrier diodes, metal oxide semiconductor field effect transistors, temperature sensors, and solar blind ultraviolet photodetectors, have demonstrated impressive characteristics especially for high-power and high-temperature applications. Moreover, β-Ga₂O₃ exhibits remarkable chemical and mechanical stability, making it well suited for operating in harsh environments.

Abstract

      In this work, improved crystal quality of (–201)-oriented β-Ga₂O₃ thin films on N-ion implanted sapphire (0001) substrates is demonstrated. Benefiting from the well-organized nucleation islands induced on the sapphire substrates through N-ion implantation, large grains are formed during the growth process. Compared to the conventional sapphire substrates, the full width at half maximum of rocking curve for the β-Ga₂O₃ (–201) plane decreases from 9.93° to 1.50°, and the root mean square roughness decreases from 16.25 nm to 9.49 nm. Meanwhile, enhanced optical performance and a high responsivity of 288 A/W for UV photodetectors, based on the β-Ga₂O₃ thin films grown on N-ion implanted sapphire substrate with an N-ion doses of 10¹² cm⁻², are achieved.

Summary

      In this work, a nucleation-induced method through N-ion implantation on sapphire substrates was proposed to improve crystal quality of β-Ga₂O₃ films. Benefiting from the increased grain size of β-Ga₂O₃ films grown on N-ion implanted sapphire substrates, the crystal quality of β-Ga₂O₃ films was significantly improved. For the β-Ga₂O₃ thin films grown on N-ion implanted sapphire with an N-ion doses of 10¹² cm⁻², its full width at half maximum (FWHM) of X-ray rocking curve (XRC) for the (–201) plane has decreased significantly. Furthermore, a high responsivity of 288 A/W was achieved for β-Ga₂O₃ UV photodetector based on the β-Ga₂O₃ film with improved crystal quality.

Graphic Abstract