Studies Of Indium Tin Oxide Thin Films On High Efficiency HIT Solar Cells

The wide use of solar cells will be a feasible way to solve the energy and environmental protection problems. The development of solar cells shows a tendency to improve efficiency and reduce cost, which become the development aim of the global photovoltaic industry. Amorphous silicon /crystalline silicon heterojunction solar cell is considered as the most hot topic and difficuty in the photovoltaic field for its advantages, such as high efficiency, great stability, simple processing, and none-pollution.This work is to achieve the high efficient heterojunction solar cells and improve the conversion efficiency and reduce the cost of crystal silicon solar cells. The contents of this thesis are as follows:Intrinsic and n-type amorphous silicon films are deposited on the substrate of p-type monocrystal silicon by Plasma Enhanced Chemical Vapour Deposition (PECVD), and indium tin oxide thin film is deposited on the n-type amorphous silicon by radio-frequrency (r.f.) magnetron sputtering to form the a-Si/c-Si heterojunction solar cells. I-V test and spectral response measurement are used to analyze the characteristics of solar cells.We study the ITO thin films from five series of substrate temperature, sputtering power, sputtering pressure, deposited time and vacuum annealing. The electrical, optical, surface morphology and microstructrure properties of ITO thin films are deeply studied by four-point probe, Cary 500 scan UV-Vis-NIR spectroscopy, Atom force microscopy (AFM) and X-ray diffractor (XRD), respectively. The resistivity of the ITO thin film reduced with the increasing substrate temperature. The resistivity first reduced and then increased with the sputtering power increased. The high quality thin film was deposited at 120 w. The sputtering pressure has effect on ITO thin film. The film deposited at 0.45 Pa has good properties. The vacuum annealing can greatly improve the electrical and optical properties of ITO thin films. After annealing, we obtained the ITO thin film with the resistivity of 2.0×10-4Ωcm and the transmittance over 90%. Used the high quality ITO thin film on a-Si/c-Si heterojuntion solar cells, and the conversion efficiency was improved greatly.