Enhance near infrared performance of n-type vertically aligned MoS2 flakes photodetector with active p-type CZTS electrodes

Abstract

Recently, MoS2 is extensively investigated as a potential 2D material to develop ultra-high responsive photodetector (PD) due to its direct band gap and high optical absorption. However, the development of broadband PD is impede due to the low light absorption of MoS2 in NIR region. Metal-semiconductor-metal (MSM) photodetector with conventional metal electrode is being used as base device structure for MoS2 PD owing its simple and cost-effective structure. However, passive metal electrodes limit light absorption and diminish the performance of photodetector. Herein, a broadband, self-powered photodetector is developed with enhanced NIR response by using n-type vertical MoS2 flakes and p-type Cu2ZnSnS4 (CZTS) active electrodes. Owing to high absorption of p-type CZTS electrode in NIR region along with MoS2 flakes in visible region and formation of p-n junction at CZTS-MoS2 flakes interface shows ultra-high responsivity of 49.31 A W−1 and external quantum efficiency of 7.6 × 103 (%) with enhanced performance in NIR and visible region in contrast to conventional and passive metal electrode. Moreover, proposed device showed very high detectivity 3.4 × 1013(2.4 × 1013) in NIR (visible) region. The responsivity with active CZTS based electrodes is increased upto 11-times in comparison to passive gold electrodes in NIR region at 1100 nm. Photodetetcor with p-type CZTS electrodes shows long term stability and reproducibility over more than 4000 h which clearly revealed advantage of using p-type CZTS electrode for MoS2 based next generation photodetector applications.