| Two-dimensional materials,due to their atomic thin thickness,unique quantum confinement effects,and excellent electrical and optoelectronic properties,are expected to play an important role in the next generation of optoelectronic devices.Various twodimensional materials with different band gaps have been discovered,ranging from semimetals,semiconductors to insulators,with detectable wavelengths covering the ultraviolet,visible,infrared,and terahertz regions.Among them,the materials that have received the most attention from researchers include graphene,black phosphorus,transition metal dichalcogenides,and boron nitride.However,photodetectors made from a single material have relatively low optical absorption,high dark currents,and are limited by the bandgap width,making it difficult to cover a broad range of wavelengths.To address these issues,researchers have proposed constructing heterostructures of two-dimensional materials to enhance the performance of photodetectors through complementary advantages between different materials.In this paper,we focus on the structural design and band engineering of novel two-dimensional heterostructure optoelectronic devices,and conduct research on the optoelectronic detection performance and transport mechanism of the devices.The main research contents and achievements are as follows:1.We conducted research on the optoelectronic detection performance of twodimensional graphene/WSe2 heterostructure devices.We designed and constructed a novel graphene/WSe2 vertical heterostructure device,and achieved high responsivity photodetection by adopting a metal electrode configuration that only contacts with the bottom graphene layer.Compared to a single WSe2 phototransistor,the optoelectronic response of graphene/WSe2 vertical heterostructure devices was improved by 2～3 orders of magnitude.Furthermore,by analyzing the photogating effect in the heterostructure device through band structure engineering,we found that the upper layer WSe2 material can confine the optically generated holes as a local photogating layer,inducing a large amount of electrons in the graphene conduction channel,thereby increasing the photo-gain of the device and achieving high responsivity optoelectronic detection.2.We conducted research on the optoelectronic detection performance of twodimensional WSe2/InSe vertical heterostructure devices.By utilizing the fast photoresponse time resolution of InSe phototransistors,we designed a novel WSe2/InSe vertical heterostructure device and investigated the photogating effect in the heterostructure device.We controlled the transport characteristics of the carrier in the heterostructure device by constructing a localized photogating field,thereby achieving both positive and negative polarity optoelectronic response detection.Through band structure engineering analysis,we investigated the carrier transport mechanism at the heterostructure interface.Furthermore,we studied the effect of different film thicknesses on the optoelectronic detection performance of the heterostructure device and found that the optoelectronic efficiency was enhanced as the film thickness increased.3.We conducted research on the optoelectronic detection performance of BP/SnS2 heterostructure devices based on Ⅲ-type band offset.High barrier BP/SnS2 heterostructure devices with Ⅲ-type band offset were prepared,and the effect of channel length on the electronic transport characteristics of the heterostructure device was studied.Through band engineering analysis,it was found that a high potential barrier was formed at the interface of the heterostructure device,which suppressed the thermal carrier transport in the channel of the device and reduced the generation of dark current.Moreover,due to the direct tunneling effect of photogenerated electron-hole pairs across the barrier region,the photoresponsivity and specific detectivity are greatly improved,reaching up to 295.3 A/W and 6.72×1012 Jones,respectively.The optoelectronic detector based on this structure overcomes the problem of difficulty in balancing high photoresponsivity and high detectivity in optoelectronic devices,achieving low power consumption,high detectivity,and high photoresponsivity... |
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