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Advanced materials: high performance p-n junction photodetectors based on local chemical modification

wallpapers News 2020-07-21
As the key device of photoelectric signal conversion

photodetector has great application potential in optical communication biological detection aerospace other fields has been widely concerned in scientific research industry. Among them the dem for a new generation of low-power small size flexible wearable photodetectors promotes the rapid development of new photoelectric materials. Transition metal chalcogenides (TMDs) such as tungsten diene (wse2) have the characteristics of flexibility high transparency high strength which provide the material basis for the development of new photodetectors. In recent years researchers have been trying to find a p-n junction based on TMDs which can efficiently realize the fast separation of photogenerated carriers to meet the application of photodetectors. Using van der Waals force to make independent p-type n-type materials vertically stack is a typical p-n structure fabrication method but the fabrication process is complex it is difficult to avoid interface defects. Therefore it is urgent to realize independent p-type n-type working regions in the same conducting channel so as to construct transversely homogeneous p-n junction.

Professor Zhang Junying Assistant Professor Wang Yuyan of School of physics Beijing University of Aeronautics Astronautics have constructed high-quality intramolecular p-n junction with excellent photoelectric properties by using a novel controllable electronic doping method for the first time. Theoretical calculation experimental results show that cetyltrimethylammonium bromide (CTAB) can effectively control the type concentration of conductive carriers in two-dimensional TMDs devices. A p-n junction photodetector with a rectification ratio of 103 was successfully fabricated by doping wse2 channel materials with local electrons. Compared with the intrinsic photodetector the switching ratio of p-n junction is increased by 1000 times the response speed is also increased by 3 times. This kind of photodetector has excellent performance the responsivity is 30 a w − 1 the external quantum efficiency is up to 7989% the specific detection is better than 1011 Jones. It has a great prospect in the application field of high sensitivity low power photodetectors. This new doping method has good controllability stability. Based on theoretical experimental studies this work reveals its unique charge transfer mechanism that is the synergistic effect of thermal emission tunneling at the metal / semiconductor interface makes electrons transfer to the two-dimensional semiconductor surface more effectively.

will play the most beautiful notes in the movement of light materials. The researchers believe that the manipulation method of in-situ chemical modification of two-dimensional materials in this work can be extended to other new generation of high-efficiency optoelectronic devices.

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