A self-powered high-performance graphene/silicon ultraviolet photodetector with ultra-shallow junction: breaking the limit of silicon?

We present a self-powered, high-performance graphene-enhanced ultraviolet silicon Schottky photodetector. Different from traditional transparent electrodes, such as indium tin oxides or ultra-thin metals, the unique ultraviolet absorption property of graphene leads to long carrier life time of hot electrons that can contribute to the photocurrent or potential carrier-multiplication. Our proposed structure boosts the internal quantum efficiency over 100%, approaching the upper-limit of silicon-based ultraviolet photodetector. In the near-ultraviolet and mid-ultraviolet spectral region, the proposed ultraviolet photodetector exhibits high performance at zero-biasing (self-powered) mode, including high photo-responsivity (0.2 A W −1 ), fast time response (5 ns), high specific detectivity (1.6 × 10 13 Jones), and internal quantum efficiency greater than 100%. Further, the photo-responsivity is larger than 0.14 A W −1 in wavelength range from 200 to 400 nm, comparable to that of state-of-the-art Si, GaN, SiC Schottky photodetectors. The photodetectors exhibit stable operations in the ambient condition even 2 years after fabrication, showing great potential in practical applications, such as wearable devices, communication, and “dissipation-less” remote sensor networks. Optoelectronics: Graphene breaks limit of silicon-based UV detection A high-performance graphene/silicon ultraviolet (UV) photodetector significantly increases the upper-limit of traditional silicon-based UV detectors. A team led by Yang Xu at China’s Zhejiang University fabricated silicon-based UV detectors using graphene with unique UV absorption property, leading to ultra-long lifetime of hot carriers that contribute to photocurrent, and even to carrier multiplication. In the near- and mid-UV regime, the improved performance parameters are photocurrent responsivity (0.20 A W −1 ), response time (100%). The key metrics of graphene/Si detector outperform those of UV detectors based on Si, GaN, SiC, etc. These results show great promise in applications such as wearable devices, secured mobile communication, and “dissipation-less” remote sensor networks.