Preparision And Characteristics Of Cuinse₂ And Its Doping Thin Films

As a direct band gap semiconductor, Cu In Se2 has advantage in high absorption efficiency(>105/cm), adjustable band gap, excellent stability, high conversion efficiency and Strong ability of resisting radiation. Cu In Se2 has won the world’s attention because it can be applied in large scale production. Cu In Se2 can be prepared by vacuum evaporation,magnetron sputtering, spin coating and solvothermal. As vacuum evaporation and magnetron sputtering took highly costs and long time, it is very important to develop a simple and low-cost method to prepare Cu In Se2.In this paper, Cu In Se2 was prepared by solvothermal method. We studied the influence of Al content on the performance of Cu In Se2 powders and thin films. Its crystal structure, morphology, band gap and the transmittance were investigated. The X-ray diffraction test was used to analyses its crystal structure and grain size. At the same time,the change of phase composition and crystal structure at different temperatures was tested by in-situ X-ray diffraction. Using scanning electronic microscopy to analysis morphology of powders and thin films and obtaining the effect of Al content on the size of particle.EDAX was used to characterize the elemental composition of samples. The relationship between wavelength and the ratio of Al/(Al+In) is tested by infrared spectroscopy, and calculate the band gap of samples with different Al content through Kubelka-Munk formula, and then obtain the relationship between the width of band gap and Al content.It was found that the intensity of XRD diffraction peak of Cu(In1-x Alx)Se2 is gradually enhanced with the Al doping increased. And the FWHM gradually becomes weak; its grain size which calculated by the Scherrer formula is gradually increased, AFM image which reflect the surface roughness of the film also increases. At the same time, the band gap of Cu(In1-x Alx)Se2 films is gradually increases along with the doping increase.For the purposes of Cu(In1-x Alx)S2 system, with the doped Al content increased,Cu(In1-x Alx)S2 XRD diffraction peak intensity gradually weakened, and the FWHM is gradually increases, and the grain size gradually become small. AFM image for the film also shows the surface roughness of the film is increases. At the same time, the band gap ofCu(In1-x Alx)S2 films is increased as the Al doping amount gradually increases. In-situ XRD tests show that the crystalline structure of Cu In Se2 do not change at 500 ℃ an aerobic environment, but when the temperature exceeds 500℃, Cu In Se2 is decomposed into Cu Se and In2Se3. When the temperature exceeds 525 ℃, Cu In S2 decomposed into Cu2 Se and In2S3, and Cu(In1-x Alx)Se2(x = 0.1) at 600℃ are very stable. Thus, the thermal stability of Cu(In1-x Alx)Se2(x = 0.1)> Cu In S2> Cu In Se2.In this paper, the effect of doping elements and doping amount on Cu In Se2, such as crystal structure, morphology, elemental composition and band gap, provides a reference for further research on CIS series.