Modulation Of Optoelectronic Properties Of Twinning In₂Se₃ Nanowires And SnS Nanosheets

Low-dimensional semiconductor materials have various quantum effects and can be processed directly using existing micro-nano processes.Therefore,they are important materials for preparing optoelectronic devices with high performance and high integration.At present,the use of crystal orientation of low-dimensional semiconductor materials to regulate their optoelectronic properties is an important way to improve the performance of semiconductor photodetectors.However,due to the difficulty in controlling the growth of the crystal direction of many low-dimensional semiconductor materials,the influence of the crystal direction on its photoelectric properties remains to be further studied.This paper mainly studies the synthetic method and the regulation by the crystal orientation for their photoelectric properties of one-dimensional In₂Se₃ nanowires and two-dimensional SnS nanosheets.The main results of the paper are as follows:?1?Longitudinal twinning?-In₂Se₃ nanowires were synthesized by Chemical vapor deposition to fabricate high performance single In₂Se₃ nanowire based photodetectors,which reveals the potential application of longitudinal twinning in optoelectronics.As-synthesized?-In₂Se₃ nanowire exhibited typical n-type semiconducting behavior with an electron mobility of 23.1 cm²V^-1S^-1.Besides,the device showed a high responsivity of 8.57×10⁵ AW^-1,high external quantum efficiency up to 8.8×10⁷%and a high detectivity of 1.58×10¹22 Jones under 600 nm light illumination at a basis of 3 V.Then the devices have a broadband spectral response.In the 350 nm-850 nm regions,the measured responsivity is as high as 10⁵ AW^-1,and the calculated EQE is as high as 10⁷%.As the incident light wavelength further increased,R and EQE slowly decrease by an order of magnitude,with R at 10⁴ AW^-1 and EQE at 10⁶%in the 850nm-1100 nm regions.And the device has excellent stability and fast response time in the 300 nm-900 nm range.Further,our current longitudinal twinning?-In₂Se₃ nanowire based device exhibits higher photocurrent,higher spectral responsivity and higher detectivity compared with other reported In₂Se₃-nanostructures devices.Such increase are due to a higher conductivity of the twinning naowires with more defects.The results indicated that the longitudinal twinning?-In₂Se₃ nanowires had immense potential for further applications in highly performance broadband photodetectors and other optoelectronic devices.?2?We used the Van der Waal heteroepitaxy method to grow two-dimensional?2D?single crystal orthorhombic SnS nanosheets,fabricated near infrared?NIR?photodetectors with 2D Sn S nanosheets,and revealed its infrared photoelectric properties and its in-plane anisotropy.As-fabricated devices exhibited excellent photoresponsivity of 365 AW^-1 and excellent external quantum efficiency of 5.70×10⁴%under NIR light illumination,which can be further increased to 635 AW^-1 and 9.92×10⁴%by Au nanoparticles decoraction.Anisotropic photoresponse was found for the SnS-based NIR photodetectors.The conductivity and photoconductivity along the zigzag direction is much greater than those along the armchair direction,because the effective mass of the carrier in the zigzag direction is smaller than that in the armchair direction,resulting in a higher carrier mobility in this direction.These results provide a deeper understanding of the electrical and photoelectrical properties of 2D SnS nanosheets based devices.