Broad-spectrum High-responsivity Photodetector Research On Nanostructure-modified Reduced Graphene Oxide

The broad spectral photodetector is designed to obtain the electromagnetic wave information of ultraviolet,visible and infrared bands,which are emitted or reflected by the target to accurately identify and analyze the target in various environments.The broad spectral photodetectors are widely used in imaging,remote sensing,medical di-agnosis,night vision and environmental monitoring fields.In order to develop the pho-todetector with wide spectrum and high responsivity,in this paper,a combination of semiconductor nanomaterials with high absorbance and reduced graphene oxide(RGO)with high transport properties is presented.Four kinds of composite thin film photode-tectors,MoS2-RGO,MoS2-RGO-MoS2,BP-RGO-BP,and ZnO-RGO-MoS2-RGO-PbS-RGO have been respectively prepared,and their photoelectric detection perfor-mance has been studied.The main research works and experimental results are as fol-lows.(1)In order to combine the high-efficiency broad-spectrum light absorption char-acteristics of MoS2 with the high-efficiency transport characteristic of RGO,the sus-pended MoS2-RGO photodetectors were designed and fabricated.The comparative study of MoS2-RGO photodetector and RGO photodetector shows that the responsivity of the MoS2-RGO photodetector is higher than that of the RGO photodetector,up to 395 mA/W.(2)In order to further improve the performance of the MoS2-RGO photodetectors,the MoS2-RGO-MoS2 photodetector was designed and fabricated.The unique structure of MoS2-RGO-MoS2 can not only absorb incident light by the MoS2 on the upper sur-face,but also absorb transmitted light by MoS2 on the lower surface,achieving two light absorption and improving responsivity of the detector.The comparative study of the MoS2-RGO-MoS2 photodetector and the RGO photodetector found that the respon-sivity of the MoS2-RGO-MoS2 photodetector is significantly higher than that of the RGO photodetector in the wide spectral range from UV(wavelength 375 nm)to NIR(wavelength 1550 nm).The responsivity of the MoS2-RGO-MoS2 detector is as high as 1006 mA/W,which reaches the A/W level.(3)The suspended BP-RGO-BP photodetectors were designed and fabricated.In the near-infrared band,especially for near-infrared light with a wavelength of 1064 nm,the responsivity of the BP-RGO-BP detector is 186.29 mA/W which is about two times that of the RGO detector.(4)The suspended ZnO-RGO-MoS2-RGO-PbS-RGO photodetector was fabri-cated by decorating nano-ZnO absorbing ultraviolet light,MoS2 nano-sheets absorbing visible light,and PBS quantum dots absorbing infrared light.From the ultraviolet band to the near-infrared band,the responsivity of the device is generally low,for example,the responsivity is 124 mA/W at the wavelength of 375 nm,68 mA/W at the wavelength of 532 nm,and 46 mA/W at the wavelength of 1064 nm.This may be attributed to the fact that the electrode of the device is located in the bottom of the composite film,which makes it cannot effectively collect the photogenerated carriers generated by the upper ZnO-RGO and the middle layer MoS2-RGO.In this paper,a composite thin film photodetector was prepared by combining sem-iconductor nanomaterials with high light absorption characteristics and RGO with high transport characteristics.By optimizing the structure of the detector,the performance of the detector was gradually improved,and the optical detection function with wide spectrum and high responsivity was basically realized.