【Epitaxy Papers】Laser-MBE Improving growth of β-Ga₂O₃ films by introducing a Homo-Amorphous nucleation seed layer for solar-blind deep UV photodetector applications

      Researchers from the Northeast Normal University have published a dissertation titled "Laser-MBE Improving growth of β-Ga₂O₃ films by introducing a Homo-Amorphous nucleation seed layer for solar-blind deep UV photodetector applications" in Materials Science and Engineering: B.

Abstract

      A high-detectivity solar-blind deep UV photodetector has been realized based on high crystalline quality β-Ga₂O₃ thin films grown by a laser molecular beam epitaxy technique, which significantly improved film quality by optimizing the growth and annealing processes of the amorphous nucleation seed layer (ANSL) to form a seed crystal layer with a (−201) preferred orientation. Compared with the thin film grown directly on a sapphire substrate, the β-Ga₂O₃ film with an ANSL exhibits a stronger and narrower (−201) crystal plane diffraction peak, and the reflection high energy electron diffraction pattern changes from dot-like to stripe-like, indicating a significant improvement in the orderliness of the crystal structure. With the increase of annealing temperature from 600 °C to 1050 °C, the absorption edges become steeper and the optical band gaps increase from 4.45 eV to 5.01 eV for the β-Ga₂O₃ thin films with ANSL. The emission spectrum demonstrated that the peak at 550 nm wavelength was suppressed, indicating the elimination of deep-level defects with an annealing treatment for the β-Ga₂O₃ thin film In Al/β-Ga₂O₃/Al metal–semiconductor-metal structured photoconductive devices, the light to dark current ratio has been enhanced nearly an order of magnitude from 10³ to 10⁴ for β-Ga₂O₃ thin films without/with the introduction of ANSL. Correspondingly, the responsivity increased from 13.78 A/W to 98.08 A/W. The response speed also increased apparently from 32 μs (rise)/38.78 ms (down) to 22 μs (rise)/2.821 ms (down) due to the improved crystal quality of β-Ga₂O₃ thin films with optimizing growth procedure.

DOI：

https://doi.org/10.1016/j.mseb.2024.117890