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【Device Papers】High-performance UV photodetector based on β-Ga₂O₃/GaN heterojunction prepared by a new route of reverse substitution growth

日期:2025-02-08阅读:169

      Researchers from the Northeast Normal University have published a dissertation titled "High-performance UV photodetector based on β-Ga2O3/GaN heterojunction prepared by a new route of reverse substitution growth" in Journal of Materials Science & Technology.

Abstract

      A broad-spectrum UV photodetector with ultrahigh detectivity and rapid response speed has been achieved in β-Ga2O3/GaN heterojunction, in which, the β-Ga2O3 is synthesized by substituting oxygen for nitrogen in the top layer of the GaN matrix at high temperature. The processes and mechanism of transforming GaN with varying crystal quality into β-Ga2O3 at high temperatures were studied in detail. The newly formed oxide layer is a monoclinic β-Ga2O3 with (-201) preferred orientation. X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM) measurements identified oxygen vacancies and surface flatness of β-Ga2O3, respectively, which are closely related to the crystal quality of GaN. The oxygen vacancies and the root mean square of morphology roughness of β-Ga2O3 decrease with the improvement of the precursor GaN crystal quality. The cross-section transmission electron microscope (TEM) measurements showed that a hexagonal phase GaNxO3(1−x)/2 intermediate layer with a thickness of 5 nm exists at the interface region between β-Ga2O3 and hexagonal GaN. This indicates a molecular reconfiguration of the hexagonal system to a monoclinic system with oxygen substitution of nitrogen in GaN matrix. The metal-semiconductor-metal (MSM) planar structure device achieved an ultrahigh detection capability (Responsivity=2493.5 A/W, Detectivity>1016 Jones). The response time is in the order of milliseconds (τr=0.27 ms, τd1/τd2=0.33 ms/4.3 ms). A self-powered UV optoelectronic rapid response (τr=5 μs, τd1/τd2=0.13 ms/2.3 ms) with the responsivity of 0.6 mA/W and the detectivity of 5.3×1011 Jones in the solar-blind wavelength region has been observed in the β-Ga2O3/GaN heterojunction without external bias. With a bias of −10 V loading, the response of the photodetector becomes a broad spectrum, covering the UVA-UVC wavelength range, and the photoresponsivity is up to 13.5 A/W. The detectivity reaches a high value of 2.6×1015 Jones.

 

DOI:

https://doi.org/10.1016/j.jmst.2024.11.032