High responsivity and detectivity β-Ga2O3 solar-blind photodetectors optimized by oxygen vacancy engineering

Abstract

Solar-blind photodetectors (SBPDs) are core essential components for many critical applications such as precision guidance, fire warning, and space communications. Ultra-wide bandgap semiconductor β-Ga₂O₃ is considered to be an ideal material for the fabrication of SBPDs. However, synthetizing β-Ga₂O₃ with high quality factor while simultaneously in situ modulation of electronic and optoelectronic properties to enhance performance has been challenging. Here, pulsed laser deposition (PLD) technology is used to synthesize high-quality β-Ga₂O₃ thin films on a sapphire substrate. The oxygen vacancy engineered β-Ga₂O₃ films can achieve in situ precise control of their surface morphology, optical parameters, and optoelectronic properties by simply adjusting the oxygen pressure. Meanwhile, the optimal thickness of the β-Ga₂O₃ film for the developing high-performance SBPD is ∼221 nm, determined by fitting and analyzing the optical parameters measured by the ellipsometry. Subsequently, the influence of oxygen pressure on the performance of β-Ga₂O₃ SBPD is thoroughly explored, considering the optimization of electrode size and deposition time. When the oxygen pressure is set to 15 Pa, the β-Ga₂O₃-based SBPD achieves highly competitive responsivity (R) and detectivity (D*) at 250 nm, with values of 1080 A·W⁻¹ and 1.4 × 10¹⁶ cm·W⁻¹·Hz^1/2, respectively. Additionally, the noise component of the β-Ga₂O₃ SBPD is further studied to calibrated the traditional device performance results. This work introduces a simple and straightforward approach to in situ tuning of the optoelectronic properties of β-Ga₂O₃, which is important for advancing β-Ga₂O₃ film growth technology and fabricating high-performance photodetectors.