High Performance Deep Ultraviolet p-i-n Self-Powered Photodetector Based on p-NiO/i-β-Ga₂O₃/n-β-Ga₂O₃ With Controlled a Fermi Level and Used an Intrinsic β-Ga₂O₃ Layer

Abstract

In this study, a high-performance deep ultraviolet p-i-n self-powered photodetector was successfully fabricated by controlling the Fermi level of the p-NiO and using an intrinsic β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> layer. Controlling the oxygen flow rate during sputtering is one of the various techniques for adjusting the Fermi level of p-NiO. A Fermi level closer to the valence band results in a higher built-in potential of the photodetector based on p-NiO/i-β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /n-β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> . As the oxygen flow rate increased from 2 to 4 SCCM, the barrier height increased from 1.08 eV to 1.43 eV. Moreover, the intrinsic layer of the photodetector can affect current density by increasing the photoactive layer and enhancing the response speed under the influence of a strong internal electric field. Thus, the photo-characteristics of the NiO/β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> photodetector exhibited a current density of 144 μA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , a responsivity of 182.5 mA/W, a detectivity of 6.61 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> Jones, and an external quantum efficiency of 89.3%, respectively. This study yields two noteworthy results. The first is the possibility of developing an unstudied DUV photodetector based on p-NiO/i-β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /n-β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> . Second, a photodetector based on p-NiO can be improved by controlling the built-in potential and adjusting the oxygen flow rate.