Ultrahigh photoresponsivity MoS2 photodetector with tunable photocurrent generation mechanism

• Published in: Nanotechnology Vol. 29; no. 48; p. 485204
• Main Authors: Wu, Guangjian, Wang, Xudong, Chen, Yan, Wang, Zhen, Shen, Hong, Lin, Tie, Hu, Weida, Wang, Jianlu, Zhang, Shantao, Meng, Xiangjian, Chu, Junhao
• Format: Journal Article
• Language: English
• Published: England IOP Publishing 30.11.2018
• Subjects: 2D materials; high photoresponsivity; photocurrent mechanism; photodetector; high photoresponsivity; photocurrent mechanism; photodetector; 2D materials
• ISSN: 0957-4484; 1361-6528
• DOI: 10.1088/1361-6528/aae17e

Photodetectors with two-dimensional (2D) materials on a SiO2/Si substrate have been extensively explored. However, these photodetectors often suffer from a large gate voltage and relatively low photoresponsivity due to the low efficiency light absorption of 2D materials. Here, we develop a MoS2 photodetector based on the Al2O3/ITO (indium tin oxide)/SiO2/Si substrate with ultrahigh photoresponsivity of 2.7 × 104 A W−1. Most of the incident light is reflected by the interface of stacked Al2O3/ITO/SiO2 substrate, which significantly increases the light absorption of 2D materials. With the help of thinner and high-κ Al2O3 dielectric, the current ON/OFF ratio could exceed 109 with a gate voltage no more than 2 V. Enhanced gate regulation also brings about a relatively high mobility of 84 cm2 V−1 s−1 and subthreshold swing of 104 mV dec−1. Additionally, two different photocurrent generation mechanisms have also been revealed by tuning the gate voltage. The reflection-enhancement substrate assisted MoS2 photodetector provides a new idea for improving the performance of 2D material photodetectors, which can be perfectly combined with other methods.