Bias-modulated Van Der Waals Heterojunction Photodetector Of Vertically Grown Graphene Nanosheets Film

With the development of science and technology,people have higher and higher requirements for sensor applications.Highly sensitive,low-cost,and easy-to-manufacture sensors have become barriers that researchers have been trying to overcome.Among them,graphene and gallium nitride are popular sensor component components and other materials with excellent optical properties.Heterojunctions are used in sensors to make them have excellent performance.Graphene has been a very popular material since it was discovered.However,due to the lack of intrinsic graphite dark current due to a band gap of zero,the photoelectric response responsivity has remained at the milliamp level.In view of the above background,this study proposes a graphene-embedded nanocrystalline carbon film,with graphene intercalation as the main structure,to study two van der Waals heterojunction sensor devices(1)graphene-embedded nanocrystalline carbon film/silicon-based Devices and(2)graphene-embedded nanocrystalline carbon film/gallium nitride devices to study their optoelectronic properties such as light response rate,response time,and spectral range.Specifically,we propose a graphene-embedded nanocrystalline carbon film under bias modulation.A van der Waals heterojunction based on a carbon film is constructed by a fixed-point transfer device,including a graphene-embedded nanocrystalline carbon film and N-type silicon.The van der Waals heterojunction and graphene nanocrystalline nanocrystalline carbon film and gallium nitride van der Waals heterojunction have been tested for their optical properties.(1)The graphene sodium crystal structure growing perpendicular to the carbon film in the carbon film.Carbon films with different nanocrystalline structures can be obtained by adjusting the electron irradiation energy(10 V to 80 V)of the electron cyclotron resonance plasma sputtering system.Different nanocrystalline structures in carbon films lead to different degrees of optical properties.The nanocrystalline structure brings high-density edges.These edges can capture electrons during the photoelectric response to increase the Fermi level of the graphene nanocrystalline carbon film and reduce the recombination rate of electrons and holes during photoexcitation.(2)For carbon film/Si devices,the van der Waals heterojunction composed of carbon film and N-type silicon base achieves a photoelectric response intensity of 92.58 A/W when the incident light is 700 nm,which is 40 times that of traditional graphene sensors.A detection rate of 3.33×10¹¹Jones was achieved at zero bias.(3)Because there are a large number of vertical graphene nanocrystalline structures,the response time of all devices is less than 500 ns.Among them,the 50V carbon film has an ultra-high-speed response time of 12.50 ns.This result can greatly increase the sensing efficiency of weak photoelectric sensors.(4)For carbon film/gallium nitride devices,the van der Waals heterogeneity composed of carbon film and gallium nitride reaches 1.93×10⁵A/W at an incident wavelength of 680 nm,and has a high sensitivity.(5)Due to the wide band gap characteristics of gallium nitride,the carbon film/gallium nitride device under violet light conditions,when the incident light is 400 nm,the light response rate reached 1.75×10⁴A/W,which is about carbon film/Si device 190 times,has better and more excellent photoelectric response performance in the violet region.