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In recent years, graphene has been considered as the "king of new materials" be-cause of its special structure and excellent physical and chemical properties. It has been widely used in electronics, energy, materials, medical treatment and other fields. In this work, we propose a controllable method for the fabrication of gra-phene layers and devices by plasma etching of graphene films. Raman spectroscopy was used to investigate the effects of conditions such as gas ion selection, plasma power and plasma gas velocity on the number of layers and property of graphene. We found that this etching method introduces defects as it makes graphene thin, ar-gon etches faster than oxygen, and the increase in plasma power and gas velocity accelerates the etching process. So, choosing proper parameters is helpful to control the speed of etching process. In addition, we fabricated field effect transistor devices with variable and controllable performance and in-plane PN junction devices by using this method, and tested the change of photoelectric performance during the etching process.PN junction can separate the photogenerated electron-hole pairs and improve the re-sponsivity of light detection. Compared with the vertical structured heterojunction, the in-plane PN junction has higher mobility and higher current density. Due to the high precision of the e-beam lithography, complex structure functional devices based on several PN junctions combination can be fabricated. The external quantum Efficiency and specific detectivity of the PN junction devices by this method are higher. The method proposed in this work is relatively simple to implement and is expected to promote the development of related applications based on graphene films.
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