【Epitaxy Papers】Low-temperature growth and photoelectric properties of β-Ga₂O₃ thin films on metallic Hf substrates by ECR-PEMOCVD

      Researchers from the Dalian University of Technology have published a dissertation titled "Low-temperature growth and photoelectric properties of β-Ga₂O₃ thin films on metallic Hf substrates by ECR-PEMOCVD" in Materials Science in Semiconductor Processing.

Abstract

      Compared to traditional sapphire substrates, metallic hafnium (Hf) offers superior lattice matching and high thermal stability (melting point >2000 °C), while also serving as the bottom electrode for vertical power devices. In this study, a GaN_mO_n/GaN composite buffer layer was constructed on a metallic Hf substrate, which acts as a nucleation template for subsequent β-Ga₂O₃ thin film growth, significantly improving crystalline quality. This structure was formed by first growing a GaN layer on the Hf substrate, followed by nitrogen-oxygen plasma treatment (NOPT) on its surface. XRD results indicate that the GaN_mO_n/GaN composite buffer layer reduced the full width at half maximum (FWHM) of the β-Ga₂O₃ (002) diffraction peak from 0.68° to 0.45°. XPS confirmed that this composite buffer layer decreased the oxygen vacancy (V_O) concentration from 9.8 % to 6.9 %. Under the optimal NOPT condition with an oxygen content of x = 0.75, β-Ga₂O₃ thin films with (002) preferred orientation were successfully grown, exhibiting a root mean square (RMS) surface roughness of 3.99 nm and an optical bandgap of 4.81 eV. The ultraviolet photodetector fabricated based on this film exhibited a photo-to-dark current ratio of 1 × 10³ and fast response times (rise time 0.11 s, decay time 0.13 s) under 254 nm illumination. Low-temperature growth of β-Ga₂O₃ on metallic Hf substrates was achieved using electron cyclotron resonance-plasma enhanced metal organic chemical vapor deposition (ECR-PEMOCVD) technology, providing a feasible approach for developing vertical power devices based on β-Ga₂O₃ on conductive metal substrates.

DOI：

https://doi.org/10.1016/j.mssp.2025.110173