Study On Doped SnS Thin Films And Devices

SnS as a new photovoltaic material which has suitable physical and chemical properties for the solar cell and photoelectric devices has good application prospect, the preparation and properties of SnS thin films and heteroj unction devices received great attention.In this thesis, the preparation and properties of SnS thin films with different thickness,Cu doped SnS thin films and its heteroj unction devices were systematicly studied.SnS thin films with different thickness were prepared on glass substrates by RF magnetron sputtering technique.The crystalline struture,composition,suface morphology,film thickness, transmittance and reflectance of the films were characterized by XRD,EDS,AFM,FE-SEM and UV-VIS-NIR Spectroscopy.The research results show that the increase of thin film thickness helps to improve the crystalline quality and component ratio of the films,and the grain sizes and particle sizes increase with the increase of the film thickness. The refractive index of samples increases with the increase of film thickness ranging from 1500nm to 2500nm.Samples have strong absorption in the visible light region with absorption coefficients on the order of 105cm4.The bandgap of film with thickness at 1042nm is 1.57eV,close to the optimum optical band gap of solar cell materials.Pure and Cu doped SnS thin films were grown onto glass subestrates using pulsed laser deposition (PLD).The crystalline struture,suface morphology,film thickness, transmittance and electrical properties of the films were investigated. The research results show that the grown films are (111) preferentially oriented,and with the increase of Cu doping density the peak assigned to (111) plane and surface roughness of the samples increase.The 10%(at%) Cu doped SnS film appered the peak assigned to (131) planes of Cu2SnS3.Compared with undoped SnS film,the absorption coefficients of 2.5%-7.5% Cu doped sample increase.The conductivity of SnS thin film significantly increase by Cu doing,the dark conductivity of 5%Cu doped SnS film is 169.0uS/cm, the light conductivity under the illumination conditions of 3.5mW/cm-1 is 438.7 uS/cm,and the ratio of light and dark conductivity is 2.59.The In/p-SnS/n-ZnS/ITO heterojuction device were fabricated on glass substrate,and the device was characterized by a semiconductor parameter characterisation system. The research results show that the device has good rectifying characteristics and weaker photovoltaic properties. Under the illumination conditions of 3.5mW/cm2,the device has the open-circuit voltage of 0.30V and short-circuit current density of 3.1 X 10-9A/cm2.