Morphological and optical tuning of β-Ga2O3 NRs/p-GaN/sapphire via precursor concentration for high-performance MSM UV photodetector application

Abstract

In this study, gallium oxide nanorods (β-Ga₂O₃ NRs) were synthesized on p-gallium nitride (p-GaN)/sapphire substrate using a hydrothermal technique with various molar concentrations of gallium nitrate hydrate (0.03 M, 0.04 M, 0.05 M, and 0.06 M) for metal-semiconductor-metal (MSM) photodetector application. An increase in molar concentration led to a corresponding increase in the thickness and aspect ratioof the NRs, as confirmed by field emission scanning electron microscopy (FESEM). Structural analysis using X-ray diffraction (XRD) revealed the monoclinic crystal structure of the β-Ga₂O₃ NRs, which was further validated by the Raman spectroscopy. UV–vis spectroscopy analysis showed a decreased band gap of the β-Ga₂O₃ NRs on increasing the molar concentration. Under 260 nm UV illumination, Pt/β-Ga₂O₃ NRs/Pt photodetector demonstrated superior performance at 0.04 M compared to the others. The device showed a responsivity of 1.19 × 10⁻¹ A/W, a detectivity of 1.14 × 10⁹ Jones, an external quantum efficiency of 56.9 %, a noise equivalent power of 2.13 × 10⁻¹⁰ W/Hz^1/2 and a sensitivity of 730.7 % at a molar concentration of 0.04 M. The present work establishes β-Ga₂O₃ NRs as a promising material for designing the high-performance MSM UV photodetector.