Semi-transparent deep-ultraviolet photodetectors based on sol-gel-synthesized MgTiO3 with a vertical architecture

Abstract

Deep-ultraviolet (DUV) photodetectors (PDs) are gaining significant importance in applications such as ultraviolet communication, monitoring, and missile detection. MgTiO3 (MTO) has demonstrated exceptional suitability for DUV PDs owing to its extensive UVC light detection ability in the superwide band (4.4-4.6 eV) and its structural and thermal stability. In this study, we fabricated a semi-transparent MTO-based self-powered vertical metal-semiconductor-metal PD using a facile solution process. Two different transparent electrodes (ITO and PEDOT:PSS) in contact with the MTO semiconductor allowed not only self-powered operation but also high transparency of the PD. The thickness of the MTO film was controlled to increase the depletion width at the semiconductor-electrode junction. In addition, the work function of the PEDOT:PSS was modulated by adding Nafion. At appropriate conditions of MTO film thickness and Nafion doping concentration in PEDOT:PSS, the device exhibited high responsivity (4.06 mA W-1) and detectivity (3.76 x109 Jones), fast response time (303/ 608 ms for rise/decay time), and good stability (over 100 cycles of on-off operations) under UVC light illumination. This study provides new insights into the cost-effective fabrication of high-performance semi-transparent DUV PD.