Performance of UV photodetector of mechanical exfoliation prepared PEDOT:PSS/<i>β</i>-Ga₂O₃ microsheet heterojunction

Abstract

The ultrawide bandgap β-Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; (4.9 eV) material possesses exceptional properties such as a high critical breakdown field (~8 MV/cm) and robust chemical and thermal stability. However, due to the challenges associated with the growth of p-type β-Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;, the preparation of homojunction devices is difficult. Therefore, the utilization of heterojunctions based on β-Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; presents a viable approach for fabricating ultraviolet photodetectors. Poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT:PSS), a p-type organic polymer material, exhibits high transparency within the 250-700 nm wavelength range. Additionally, its remarkable conductivity (&gt;1000 S/cm), high hole mobility (1.7 cm&lt;sup&gt;2&lt;/sup&gt; V&lt;sup&gt;-1&lt;/sup&gt; S&lt;sup&gt;-1&lt;/sup&gt;), and excellent chemical stability render it an outstanding candidate for serving as a hole transport layer. Consequently, the combination of p-type PEDOT:PSS with n-type β-Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; in a heterojunction configuration offers a promising avenue for the development of PN junction optoelectronic devices.&lt;br&gt;In this study, a β-Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; microsheet with dimensions of 4 mm in length, 500 μm in width, and 57 μm in thickness was successfully exfoliated from a β-Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; single crystal substrate using a mechanical exfoliation technique. Subsequently, a PEDOT:PSS/β-Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; organic/inorganic p-n heterojunction UV photodetector was fabricated by depositing the PEDOT:PSS organic material onto one side of the β-Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; microsheet. The resulting device demonstrates typical rectifying characteristics and exhibits sensitivity to 254 nm ultraviolet light, along with impressive self-powered performance. Furthermore, the heterojunction photodetector demonstrates exceptional photosensitive properties, achieving a responsivity of 7.13 A/W and an external quantum efficiency of 3484% under 254 nm illumination (16 μW/cm&lt;sup&gt;2&lt;/sup&gt; ) at 0 V. Additionally, the device exhibits a rapid photoresponse time of 0.25/0.20 s and maintains good stability and repeatability over time. Notably, after a duration of three months, the photodetection performance of the device towards 254 nm UV light remained consistent, without any significant degradation. This comprehensive research offers a novel perspective and theoretical foundation for the development of innovative UV detectors, paving the way for future advancements in the field of optoelectronics.