Charge-carrier engineering of staggered-gap p-CuAlO2/β-Ga2O3 bipolar heterojunction for self-powered photodetector with exceptional linear dynamic range and stability

Beta-gallium oxide (β-Ga2O3)-based heterojunction photodetectors (HJPDs) based on p-n heterojunction have drawn a lot of attention since p-type doping of β-Ga2O3 is challenging to perform. Thus, choosing affordable and effective inorganic hole transport layers (HTLs) is a crucial first step in commercializing PDs. Copper aluminum oxide (p-CuAlO2) is a very likely candidate material for heterojunction with β-Ga2O3, because of its large hole mobility for use in solar-blind photodetectors and high-power electronics. In this study, we propose employing a p-CuAlO2 interlayer for built a β-Ga2O3-based SBUV HJPDs by regulating the oxygen flow rate (OFR) from 0 % to 30 % using the RF magnetron sputtering (RFMS) technique. Prior to building the p-CuAlO2/β-Ga2O3 HJPDs, the heterojunction band alignment was established and displayed staggered-gap band alignment with a valence band (ΔEV) offset of 1.1 eV and conduction band offset (ΔEC) of 0.65 eV with OFR of 30 %. In response to the UV-C (255 nm) wavelength, the good optoelectronic device properties such as low dark current of ∼10−12 A, large photo-to-dark current (Ilight/Idark) ratio (∼104), responsivity (R) (26.36 mA/W), detectivity (D*) (2.87 × 1010 cmHz1/2W−1), external quantum efficiency (EQE) (1.28 × 104 %), noise-equivalent power (NEP) (0.03 pWHz−1/2), linear dynamic range (LDR) (99.13 dB), and comparable rise (τr) and decay times (τd) of 0.25 s and 0.15 s respectively, were demonstrated for p-CuAlO2/β-Ga2O3 HJPDs with OFR of 30 % and also compared with pristine Pt/β-Ga2O3 Schottky barrier diode photodetector (SBDPD). The band offset at the p-CuAlO2/β-Ga2O3 interface is employed to explain the improvement of p-CuAlO2/β-Ga2O3 HJPDs. The incorporation of p-CuAlO2 into Pt/β-Ga2O3 SBDPD lead to an improved extraction efficiency of the generated free hole carriers under illumination. The Silvaco TCAD simulator was employed to get insight into the function of the p-CuAlO2 layer. The investigation focused on analyzing the variation profile of the recombination rate and electric field in Pt/β-Ga2O3 SBDPD and p-CuAlO2/β-Ga2O3 HJPD with OFR of 30 %. The outcomes demonstrate the stability and electron transfer impact of staggered gap p-CuAlO2/β-Ga2O3 HJPDs. Our findings show that the p-CuAlO2/β-Ga2O3 HJPDs have a great deal of potential as a candidate structure for the Ga2O3-based modern optoelectronic technologies.