Optoelectronic characteristics of bilayer graphene/ZnO nanowires heterojunction UV photodetector for IoT applications: A simulation study

This paper presents a simulation study of a highly sensitive ultraviolet (UV) photodetector designed for next-generation Internet of Things (IoT) applications, requiring real-time monitoring and energy-efficient performance. The study, conducted at room temperature, investigates the photodetection properties and optoelectronic characteristics of an optimized heterojunction based on p<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+-</sup>bilayer graphene (p<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup>-BLG) and n<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">–</sup>-zinc oxide (n<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">–</sup>-ZnO) nanowires (NWs). The design and analysis are performed using Silvaco Devedit and Atlas TCAD software, focusing on the UV spectral region. The heterojunction of p<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup>-BLG/n<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">–</sup>-ZnO NWs exhibits a high rectification ratio of 1.8×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> at ±1 V, a low zero-bias dark current density of 1.2 μA/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, and an impressive J<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">light</inf>/J<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dark</inf> ratio of 4.6×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup>. The photodetector demonstrates rapid response with a photoswitching time of 0.32 ns and a 3-dB cut-off frequency of 1.1 GHz at -0.5 V bias. Performance metrics include a peak quantum efficiency of 42%, a peak photocurrent responsivity of 0.11 A/W, a peak specific detectivity of 1.52×10⁹ Jones, and a minimum noise equivalent power of 1.91×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">–14</sup> W/Hz<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> at –1.0 V, surpassing previously reported results. These characteristics, combined with its low power consumption and high sensitivity, make the proposed photodetector highly suitable for next-generation IoT-based UV sensing applications requiring real-time monitoring and energy-efficient performance.