High-Performance <i>β</i>-Ga₂O₃ MISIM Solar-Blind Photodetectors With an Interfacial AlN Layer
Chuanlun Zhang, Chengyi Tian, Shubo Wei, Ziling Cai, Hao Long, Jie Zhang, Rongdun Hong, Weifeng Yang
Abstract
We report on 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> -based metal-semiconductormetal (MSM) and metal-insulator-semiconductor-insulator-metal (MISIM) solar-blind photodetectors with high responsivity and high speed. The 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> MSM photodetector exhibits a low dark current of 8.91 pA, a high responsivity of 247 A/W, a high response speed of 0.32 s, and a high external quantum efficiency ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">EQE</i> ) of 1.21 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> %, which is ascribed to high-quality film grown by molecular beam epitaxy. Interestingly, the performance of 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> MSM photodetector can be tuned in trade-off balance by inserting an ultrathin interfacial AlN layer by atomic layer deposition. The 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> MISIM photodetector with a 3 nm AlN interfacial layer shows an improved responsivity of 482 A/W, a higher <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">EQE</i> of 2.36 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> %, and a faster response time of 0.10 s, and a deteriorating dark current of 0.17 nA. Additionally, a type I band alignment at the AlN/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> interface is identified by X-ray photoelectron spectroscopy and the corresponding migration of carriers at the interface are used to explain the observed results. Our study suggested a great potential for high-performance 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> photodetectors through an AlN-engaged interfacial engineering.