Study Of Sulfide Low Dimensional Semiconductor Materials And Optoelectronic Devices

Low-dimensional semiconductor materials with in-plane anisotropic optical,electrical,and thermal characteristics due to their low symmetry crystal structure,which have shown potential application in polarization pulse generator,polarization image sensor,polarization-sensitive photodetector,and other fields.Exploring novel lowdimensional semiconductor materials,developing their unique properties,and expanding their practical applications have always been the core research hotspots of low-dimensional materials.In this thesis,the optical and photoelectric properties of 1D Bi2S3,quasi-1D Sb Bi S3 and 2D Bi2S3,semiconductors are systematically studied.Their application in polarization imaging is also explored.The main contents and results are as follows:(1)Low-noise dual-band image sensor based on 1D Bi2S3 nanowire: Theoretical calculation demonstrated that Bi2S3 bulk material has an indirect band gap of 1.7 e V and shows anisotropic absorption coversing visible and near-infrared wavelength.Experimentally,we prepared high-quality 1D Bi2S3 nanowires by sulfur-assisted chemical vapor deposition(CVD).The experimental results show that 1D Bi2S3 nanowires have strong anisotropy in optical properties and Raman scattering.The AuBi2S3-Au device based ona single Bi2S3 nanowire was fabricated and exhibits excellent device performance,such as high photoresponsivity(32 AW-1),Ion/Ioff ratio(1.08×104)and anisotropic photocurrent ratio(1.9).In particular,the noise power spectral density of the photodetector is only 4.39 p A h Z1/2(532 nm)and 3.94 p A HZ1/2(808 nm)at the frequency of 1 Hz,and the Hooge parameter is 2.0×10-5,which refer to lower noise than most reported low-dimensional materials-based devices.In addition,the device achieves high resolution direct polarization imaging in both visible band(532 nm)and near infrared band(808 nm).This work shows that Bi2S3 nanowires have potential applications in polarization detection and polarization imaging,provideing a theoretical basis for the study of one-dimensional nanomaterials in polarized light sensors.(2)Cation alloying induced blue-shifted and wide-spectrum polarization-sensitive photodetection in quasi-1D Sb Bi S3: Sb Bi S3 single crystal was synthesized by chemical vapor transport(CVT)method,and quasi-1D Sb Bi S3 nanowires were obtained by mechanical exfoliation method.The results of HRTEM,SAED and XRD show that the prepared Sb Bi S3 crystals have an orthorhombic structure with high crystallinity and uniform element distribution.It is found that Sb Bi S3 crystals are stacked along the caxis and grow along the a-axis.The optical and photoelectric properties of quasi-1D Sb Bi S3 nanowires were further studied by theoretical calculation and experimental characterization.The bulk material Sb Bi S3 with obvious optical anisotropy along the different directions of the crystal has an indirect band gap of 1.96 e V,exhibiting strong optical absorption in the near ultraviolet and visible regions.The polarization sensitive photodetector based on the gold-Sb Bi S3-gold type was fabricated.The Sb Bi S3-based photodetector shows fast response speed under 532 nm laser,with the response time of 10 μs(up)and 94 μs(down).The device shows wide-spectrum photosensitivity(360 ~1064 nm).The anisotropic photocurrent ratio at 808 nm is 1.12.This work demonstrates that the Sb Bi S3 semiconductor prepared by cationic alloy is a promising candidate for the application of polarized optoelectronics.(3)Wide-spectrum polarization-sensitive photodetector based on 2D Bi2S3 nanosheets: 2D Bi2S3 nanosheets with regular morphology were synthesized on Si/Si O2 substrates for the first time by the method of chemical vapor deposition(CVD).The 2D Bi2S3 nanosheets have an orthorhombic crystal structure,uniform element distribution,high crystallinity,and anisotropic optical properties.The field effect transistor test shows that 2D Bi2S3 nanosheets have the characteristics of n-type semiconductor.The 2D Bi2S3 nanosheet photodetector exhibits a good broadband photoresponse,ranging from ultraviolet(360 nm)to short-wave infrared(1550 nm).The anisotropic photocurrent ratio of the device at 808 nm is 1.4.In addition,the noise power density of the detector is 1.1p A Hz-1/2(1 Hz)when the bias voltage is 0.1 V and the gate voltage is 50 V.This work proves that 2D Bi2S3 nanosheets with in-plane anisotropy have potential in the application of polarization-sensitivity photodetection.