Research Advances in Research of Microwave Midwave Infrared Photodetectors in Nanjing University

In recent years, China Wave Infrared has gained more and more important applications in thermal imaging, molecular identification, free space communications, and optical radar, all requiring high sensitivity at room temperature.

At present, the mainstream technology of uncooled (room temperature) infrared detectors is a thermistor-type microbolometer, but the device has a lower detection rate and a slower response time. In response to this technical challenge, Prof. Feng Han's research group and research cooperation team of Nanjing University’s School of Physics used a new narrow band gap two-dimensional material “black arsenic phosphors” (b-AsP) and related van der Waals heterojunctions to successfully achieve room temperature performance beyond The highly sensitive medium-wave infrared photoelectric detection of existing commercial technologies has taken an important step in promoting the application of two-dimensional materials in the field of infrared detection.

In recent years, the research group has made some progress in the field of two-dimensional visible and near-infrared photodetectors (Nano Lett. 16, 2254 (2016); Adv. Func. Mater. 26, 1938 (2016).). Based on this work, a new type of narrow bandgap two-dimensional material such as black arsenic phosphorous was selected. This type of material is obtained by doping the elemental arsenic group with black phosphorus. A specific ratio of black arsenic phosphorous b-As0.83P0.17 has been found to have a band gap that can be adjusted to ~0.15 eV, demonstrating its potential application in the mid-infrared detection field. . In this work, a thin layer sample of b-As0.83P0.17 was first obtained by mechanical cleavage method. A field-effect phototransistor was fabricated. The response of medium-wave infrared (8.05μm) was observed at room temperature (Figure A). Atmospheric windows. Through further systematic research on the working mechanism of the detector, it was found that the photovoltaic effect and the photo-thermoelectric effect would play a leading role under different back gates (Figure B). In order to overcome the challenges of narrow-bandgap semiconductor dark current and noise at room temperature, resulting in a significant reduction in device performance, Prof. Feng's group adopted a two-dimensional material orientation transfer process and differently doped n-type MoS2 and b-As0.83P0 The .17 (p-type) stacks together to form a van der Waals heterojunction (Figure C). The test results show that the heterojunction of this structure effectively reduces the dark current and noise of the device. The detection ratio at room temperature can be as high as 5 ́ 109 Jones, which is nearly one-fold higher than the peak detection rate of the widely used PbSe infrared detector. Grade (Figure D). This result also fully demonstrates the great potential of van der Waals heterojunctions based on narrow band gap two-dimensional materials in the field of medium-wave infrared detection.

Fig. (A) Response signal of medium-wave infrared at 8.05 μm for black arsenic-phosphor-phosphor field-effect devices at room temperature, inset: Photovoltaic response of the device (top) and schematic diagram of the structure (below); (B) Light of black arsenic-phosphorus field-effect device The relationship between current and bias voltage and gate voltage reveals that the photovoltaic effect and photo-thermoelectric effect play a leading role respectively; (C) Photomicrograph of a b-AsP-MoS2 heterojunction photodetector, scale 5μm; (D) at room temperature b- The specific detection rate of the AsP-MoS2 heterojunction photodetector is compared with commercial PbSe detectors and commercial thermistor detectors.

This work was published in the June issue of the Science Advances magazine on June 30, 2017 under the title "Room temperature high-detectivity mid-infrared photodetectors based on black arsenic phosphorus" (Science Advances, 3, e1700589 (2017) ).

Dr. Long Mingsheng and Gao Anyuan, Ph.D. students at Nanjing University’s School of Physics, were the first authors of the paper's joint contributions. Prof. Qi Feng, Professor Wang Xiaomu of the Institute of Electronics, and Hu Weida, a researcher at Shanghai Institute of Technology and Physics, served as the co-corresponding author of the paper. The collaborators also include Prof. Xu Jianbin of the Chinese University of Hong Kong, Prof. Tom Nilges of the Technical University of Munich, Prof. Lu Wei of the Shanghai Institute of Technical Physics and Prof. Chen Xiaoshuang.

The study was supported by the Collaborative Innovation Center of Microstructure Science and Technology, the National Fund for Distinguished Young Scientists, the National Quantum Scientific Research Program of the Ministry of Science and Technology (Young Scientists Project), Jiangsu Outstanding Youth Fund, and the National Natural Science Foundation of China Funding for such projects.

(Original Title: Prof. Qi Feng's Research Group and Cooperative Team Reports Important Advances in Room Temperature Wave-infrared Photodetectors in the Science Sub-item)