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Research Of Self-driven Photodetector Based On Graphene-WSe2-Au Structure

Posted on:2021-02-26Degree:MasterType:Thesis
Country:ChinaCandidate:S Y ZhangFull Text:PDF
GTID:2428330611966411Subject:Microelectronics and Solid State Electronics
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With the discovery of graphene,two-dimensional materials have aroused wide interests in academia and industry.Photodetectors based on traditional semiconductor materials have been unable to meet the needs of the rapid development of today's science and technology.Due to the excellent electrical and optical properties of two-dimensional materials,they have great development potential in the field of photodetection.Photodetectors based on two-dimensional material heterojunction structure can operate without any external bias due to the presence of an internal electric field,which is called self-driven characteristics.Self-driven photodetectors have important applications in the fields of internet,wearable electronic devices,remote sensing and outdoor environment monitoring.In this paper,a Metal-Semiconductor-Metal?MSM?self-driven photodetector based on WSe2 material was designed,with graphene and gold as electrode materials.Among them,WSe2 and graphene slice materials are obtained by means of micromechanical exfoliation.The WSe2-Au and WSe2-Graphene junctions are formed by prefabricated-metal two-step dry transfer method,which avoids the disorder and impurities of the gold-semiconductor contact surface caused by steps such as photolithography,developing and electron beam evaporation during the traditional fabrication of heterogeneous devices.The M-S junction we produced is equivalent to van der Waals heterojunction,which effectively avoids the Fermi level pinning effect,and the device displays a good photovoltaic effect.Under the condition of no external bias,at 650nm red light,the device's responsivity is up to 7.55A/W,and the detectivity is up to3.0×1012Jones,indicating that the device has excellent light response ability and weak-light-detection ability.Besides,it has ultrahigh photocurrent to dark current ratio of 108.In addition,at 450nm,532nm and 780nm,our device also shows good light response.Because the gate voltage has a regulatory effect on the Fermi level of the lamellar graphene and WSe2,the device shows gate tunable characteristics.In addition,through COMSOL-based finite element simulation,we verified the reason of self-driven characteristics of the photodetector,and it has a wide-band optical response,which is consistent with the test results of the physical device.It is worth noting that the optical responsivity of our photodetector shows a linearity with the incident light power density up to 60d B,which has a great application prospect in practical electronic devices.
Keywords/Search Tags:Two-dimensional materials, Self-driven photodetector, Van der Waals heterojunction, Fermi level Pinning, Prefabricated-metal two-step transfer
PDF Full Text Request
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