Study On Controlled Synthesis Of 1D Ⅱ-Ⅵ Nanostructures And Arrayed Broad Spectrum-based Photodetectors

One-dimensional（1D）Ⅱ-Ⅵ semiconductor nanomaterials,as a direct bandgap semiconductor material,have great potential for applications in highly integrated optoelectronic devices and new types of devices due to their excellent physical and chemical properties.Although many researchers have reported various Ⅱ-Ⅵ nanostructures for applications in photodetectors and new optoelectronic devices,the limitation of the bandgap in semiconductor materials in nature has caused inconvenience to the application of semiconductor nanodevices.To overcome this limitation,this study is based on the bandgap modulation of CdS_xSe_1-x.By optimizing the CVD system,various nanostructures with different bandgaps and single nanostructure with uniformly graded bandgaps were grown.Based on the successfully developed micro-nano transfer system,an arrayed multi-nanomaterial detector with wide spectral selectivity was prepared on silicon and flexible substrates,and a single nanostructure detector combined with an arrayed electrode was prepared on a silicon substrate,realizing the expansion of the spectral response range and the improvement of the performance of the photodetector.The main research contents are summarized as follows:（1）Using an improved dual-temperature zone CVD system,1D CdS_xSe_1-x nanostructures with different band gaps were grown on silicon substrates.The nanostructures were characterized using various techniques such as SEM,XRD,Microscopic fluorescence,and Micro-PL.The results indicate that the 1D nanostructures grown exhibit typical single-crystal wurtzite structures with high crystallinity,no significant defects or impurities,and uniform band-edge emission.（2）This research established a micro/nano transfer platform and,based on UV lithography and wet etching processes,used PDMS to fabricate micro/nano triangular stamps.By employing the thermal release principle,This research successfully arranged 1D nanostructures with different band gaps in an array pattern at the marked location on the substrate.（3）This research fabricated high-performance optoelectronic detectors with wide spectral selectivity on silicon（SiO₂/Si）and flexible（PET）substrates.The performance test results exhibited ultra-broad wavelength spectral detection（450-750nm）,excellent spectral responsivity（～10 AW）,high on/off ratio（10）,fast response and recovery speed,and high-level environmental light stability.In addition,the flexible device also showed excellent folding resistance and bending light stability.（4）This research demonstrate an optimized mobile-source growth method to grow 1D CdS_xSe_1-x nanostructures with a uniformly varying bandgap in a dual-temperature CVD system.By combining electron beam lithography,we fabricated devices with a single nanowire combined with an array electrode that exhibit excellent photoresponse.We further analyzed the"type-Ⅱ" band structure by creating an optimized band alignment to maximize the driving force of CdSe excitons injected into CdS via CdS_xSe_1-x,resulting in higher photoresponse.