Zhenhua Ni

2D Materials

School of Physics, Southeast University

Email: zhni@seu.edu.cn

Biography

    Dr. Zhenhua NI is currently a professor and Dean in School of Physics at Southeast University (SEU, China). He received Bachelor’s degree in Physics and a second Bachelor’s degree in Applied Electrical Techniques from Shanghai Jiaotong University in 2003, Ph.D. degree in Physics from National University of Singapore (NUS) in 2007, and did his postdoctoral research in Department of Physics and Applied Physics at Nanyang Technological University (NTU) from 2007-2010. His current research interests include the spectroscopic investigation of two dimensional materials and their applications in optoelectronic devices. He has published more than 160 papers in peer-reviewed journals, and received over 16000 citations with H-index of 6`. He was identified in the 2019 Highly Cited Researchers list from the Web of Science Group. He is the expert of the International Electrotechnical Commission (IEC) and member of National Technical Committee 279 on Nanotechnology of Standardization Administration of China, and is the drafter of 4 Chinese National standards.

Abstract for Presentation

Defect and interface engineering of two dimensional materials

   Two dimensional (2D) materials have shown great potential in the application of optoelectronic devices, because of their unique optical and electrical properties. The performance of optoelectronic devices based on 2D materials is strongly influenced by defects and the interface. In this talk, we will present our results on the defect and interface engineering of 2D materials to improve the performance of photodetectors. We demonstrate that the trap states in two-dimensional ReS2 could be efficiently modulated by defect engineering through molecule decoration, and both the response time and responsivity of the device are greatly improved. We further elaborate that plasmon-induced hot electron transfer (HET) from tungsten suboxide nanocrystals to graphene is a sufficient fast process (<150 fs) to prevent carrier cooling and trapping processes. A fast near infrared (NIR) detector empowered by HET is demonstrated, and the response time is three-orders of magnitude faster than that based on common band-edge electron transfer. Finally, based on the intefacial gating mechanism, we successfully demonstrate a graphene based position sensitive detector (PSD), which shows excellent position sensitivity, fast response and low degree of non-linearity, and extends the operating wavelength to the near infrared (IR) region. Our results indicate that defect and interface engineering is a new strategy for implementation of efficient and high-speed optoelectronic devices.

References

1.    Jiang J, Ling CY, Xu T, Wang WH, Niu XH, Zafar A, Yan ZZ, Wang XM, You YM, Sun LT, Lu JP, Wang JL*, Ni ZH* Defect Engineering for Modulating the Trap States in Two-dimensional Photoconductor Advanced Materials 30, 1804332 (2018)
2.    Liu KY, Wang WH, Yu YF, Hou XY, Liu YP, Chen W, Wang XM, Lu JP*, Ni ZH* Graphene-Based Infrared Position-Sensitive Detector for Precise Measurements and High-Speed Trajectory Tracking Nano Letters 19, 8132-8137 (2019)
3.    Yu YF, Sun Y, Hu ZL, An XH, Zhou DM, Zhou HZ, Wang WH, Liu KY, Jiang J, Yang DD, Zafar Z, Zeng HB, Wang FQ, Zhu HM, Lu JP*, Ni ZH* Fast Photoelectric Conversion in the Near-Infrared Enabled by Plasmon-Induced Hot-Electron Transfer Advanced Materials 31,1903829 (2019)
4.    Jiang J, Xu T, Lu JP, Sun LT*, Ni ZH* Defect engineering in 2D materials: precise manipulation and improved functionalities Research 10.34133/2019/4641739 (2020). 
5.    Wang WH, Liu KY, Jiang J, Du RX, Sun LT, Chen W, Lu JP, Ni ZH* Ultrasensitive graphene Si position sensitive detector for motion tracking. InfoMat (2020)