Near-infrared Integrated Photodetector Based On PdSe₂ NWs Film/Si Heterojunction

With the rapid development of semiconductor technology and the advent of the post-Moore era,the devices based on small size nanomaterials to improve the density of integration has become one of the choices.One-dimensional semiconductor nanomaterials have high surface-to-volume ratio,length-to-diameter ratio;the radial and axial directions show significant optical anisotropy and the one-dimensional structure makes the carriers transport along the axial direction,thus providing a more efficient transfer channel.All these unique properties make one-dimensional semiconductor materials have great application prospects in optoelectronic devices.PdSe₂ belongs transition metal dichalcogenide(TMD)materials with tunable bandgap and widely applied in various optoelectronic devices as one of the two-dimensional layered material.However,there are few reports on the synthesis of its one-dimensional structure and the optoelectronic properties.In this work,we present a PdSe₂ nanowires(NWs)film/Si heterojunction-based NIR integrated photodetector.The large-area PdSe₂ NWs are synthesized via thermal-assisted selenization of pre-grown Pd NWs,and the integrated photodetector with 8×8 device units is obtained by assembly and transfer of the NWs atop Si substrate.Optoelectrical characterization reveals that the as-fabricated device shows obvious photoresponse in a broad wavelength spectrum covering 200-1300 nm with a peak response at around 810nm and a fast response speed.Under 810 nm light illumination,the device has a responsivity(R)of 166 m A·W^-1 and a specific detectivity(D*)of 2.26×10¹⁰ Jones at zero bias,which can be greatly enhanced by about 19 times to 3.24 A·W^-1 when applying a-2V bias voltage.The light absorption curve proves that the device structure increases the light absorption of individual Si in the ultraviolet and near-infrared region,thus enhancing the photoelectric performance of the PdSe₂ NWs film/Si heterojunction photodetector.Besides,the integrated device exhibits an excellent uniformity,and all 64 devices have current on/off ratio around 60.Benefiting from the good photoresponse uniformity,the integrated photodetector can be applied in trajectory tracking,reprinting the relatively complex track of light spot.In addition,the integrated device can also serve as an optical image sensor to reliably record a“LASDOP”pattern projected by a NIR light irradiation.