Research group of Professor Peng Hailin and researcher Liu Kaihui of Peking University have made important progress in two-dimensional bi2o2se ultra fast and high sensitive infrared chip materials

In the past century, infrared detection has become an important means for people to observe nature, and the application based on infrared detection has penetrated into all aspects of people's life, such as safety monitoring, action detection, infrared night vision, etc In the wavelength range of 0.7 μ m ~ 1 mm infrared light, the 1 ~ 1.8 μ M band short wave infrared light is particularly concerned because of its unique application In history, the main driving force of the development of photoelectric detection is the discovery of new photoelectric materials and the improvement of processing technology After a century of efforts, it has been found that different bulk materials with high quantum efficiency and adjustable band gap in infrared spectrum include HgCdTe, InGaAs, InSb, GaAs / AlGaAs Quantum Wells and InAs / GaSb superlattices in III-V and II-VI compounds However, the high-quality films of these materials are difficult to prepare and follow-up micro nano processing, so the cost of preparing these materials into high-resolution infrared imaging equipment will rise sharply Therefore, an important development trend of infrared detection chip is to combine infrared sensing materials with cheap and mature silicon-based chip readout circuit, so as to achieve higher pixel, higher frame rate and more complex signal processing functions The recent rise of two-dimensional materials provides a good opportunity for the development trend of this kind of infrared detector The two-dimensional materials have unique ultra-thin planar structure, excellent mechanical properties and flexibility, which makes it easy to process into focal plane array and compatible with silicon-based chip readout circuit Sensitivity and response time are the two core indexes of infrared detector For practical application, channel material is required to have good air stability at the same time However, the reported infrared detectors based on two-dimensional materials can not meet the above conditions at the same time For example, graphene shows high-speed photoelectric response, but its sensitivity is low, typical value is less than tens of MA / W The traditional transition metal disulfide (TMD) usually has too large band gap, so it loses the ability to detect infrared light Black phosphorus has good infrared detection ability, but its chemical instability is not compatible with large-scale manufacturing process Therefore, people are still looking for two-dimensional layered materials that can be used for high sensitivity and fast infrared detection In the past two years, Professor Peng Hailin's research group and collaborators of School of chemistry and molecular engineering of Peking University have discovered for the first time a new type of two-dimensional semiconductor chip material (Bi 2O 2 se, Bi 2O 2 SE), which has the characteristics of ultra-high electron mobility, suitable band gap, environmental stability and mass production , the field effect transistor devices, quantum transport and visible light detection show excellent performance (nature nanotech 2017, 12, 530; nano lett 2017, 17, 3021; adv mater 2017, 29, 1704060) Recently, they and their collaborators found that the prototype photodetector made of Bi 2O 2SE has a wide spectral response (from visible light to 1700 nm short wave infrared region) and a high sensitivity (up to ~ 65A / W at 1200 nm near infrared region 2) The dynamic scanning of ultrafast photocurrent using femtosecond laser shows that the detector has an intrinsic ultrafast photocurrent response time of about 1 picosecond (10-12 seconds) In addition, the compound is composed of alternating stacking Bi 2O 2 and Se layers The presence of oxygen in the crystal makes it extremely stable in the air It can be completely exposed to the air for several months and remains stable They also demonstrated the use of a single Bi 2O 2 se photodetector to achieve high-resolution infrared imaging at room temperature by scanning on the imaging plane Due to its two-dimensional material properties, the photodetector can be fabricated on a flexible substrate and can work normally in the 1% stress range In addition, they showed that multiple arrays of Bi 2O 2 se photodetectors can be imaged in collaboration, thus having the potential of multi-pixel scanning imaging Because Bi 2O 2SE has the potential to integrate with silicon-based readout circuit, and the preparation process is simple, it has the possibility of large-scale production, which opens a new path for flexible infrared photoelectric detection and imaging with high sensitivity, high speed, low cost and room temperature operation The research results were published in NAT Commun under the title of "ultrafastand highly sensitive infrared photodetectors based on two-dimensional oxide crystals" (DOI: 10.1038 / s41467-018-05874-2) Professor Peng Hailin and researcher Liu Kaihui of the school of physics of Peking University are co authors of the work The co authors of this paper are Dr Yin Jianbo, Tan Zhenjun, Hong Hao and Dr Wu Jinxiong The work was supported by the Ministry of science and technology and the National Natural Science Foundation of China.