Transparent, low dark current, fast response ultraviolet and short-wavelength blue photons photodetector based on Graphene/SrTiO3 single crystal

Abstract

Ultraviolet light and short-wavelength blue photons (UV-SWB) can cause damage to the human body under excessive exposure. Strontium titanate (SrTiO3), which is a crucial perovskite oxide with a direct energy band gap of ∼3.2 eV, has great potential for UV-SWB photodetection. In this work, UV-SWB photodetector with high transparency based on Graphene/SrTiO3 heterojunction was fabricated by graphene transfer method. The Graphene/SrTiO3 photodetector exhibits an ultra-low dark current of 6 pA at a 30 V bias. The response spectrum of the Graphene/SrTiO3 photodetector was 220–410 nm, covering the UV-SWB band. Under 385 nm light irradiation, the photodetector exhibits a response of 3.4 mA/W, a detectivity of 1.5 × 1010 Jones, a response time of 186 ms, and a light-to-dark current ratio of 103 magnitude at a 30 V bias. In addition, the transmittance of the photodetector in the visible light band reaches 80 %, which has excellent visualization performance. The excellent performance of Graphene/SrTiO3 photodetector is attributed to the high crystal quality of SrTiO3 wafer and the van der Waals interface constructed by Graphene/SrTiO3 reduces the bulk defect density and interfacial state density, which could be beneficial the separation and transport of photogenerated carriers in the active layer and heterojunction. This study has important reference value for the design and manufacture of UV-SWB photodetectors.