P-type Of ¦Ìc-si: H Thin-film Micro-structure And Optoelectronic Properties

Microcrystalline silicon thin film solar cell has the advantages of both crystalline silicon solar cell and thin film solar cell, so it is believed as the next generation technology of silicon film solar cells. In pin type microcrystalline silicon thin film solar cells, p layer is used as window materials. And it is very critical for the solar cell performance, p-type hydrogenated microcrystalline silicon (μc-Si:H) should have higher crystalline fraction volume, higher conductivity, wider Optical band gap, so it has importance influence on increasing solar cell efficiency to study microstructure and optoelectronic properties of p-typeμc-Si:H film.In this paper, p-typeμc-Si:H films were prepared on glass by using radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) method. The influence of deposition parameters include boron doping percentage, substrate temperature, plasma power and pressure on the microstructure, deposition rates and optoelectronic properties were studied systematically. Then p-type silicon films of different deposition time and different substrate were preliminary analyzed. After above investigates, we studied microcrystalline silicon film window layers of different doping percentages influencing on the properties of solar cells.The main results obtained in this paper are as follows: the crystalline volume fraction of films decreases gradually with the increase of doping percentage. In some ranges increasing the substrate temperature, plasma power and pressure will improve the crystalline volume fraction. But going on increasing the substrate temperature, plasma power and pressure will depress it. The deposition rates increase with the increase of boron doping percentage, substrate temperature, plasma power and pressure, but the deposition rates tend to saturate when the pressure is over 2Torr. The dark conductivity of films firstly increases, and then decreases with the increase of boron doping percentage, substrate temperature and pressure. On the whole, the dark conductivity decreases with the increase of plasma power. The optical band gap decreases with the increase of doping percentage, substrate temperature and plasma power, but it starts to increase when the plasma power is higher. There is a amorphous silicon incubation layer between the interface of the substrate and p-typeμc-Si:H film. Comparing with glass, SnO₂/ZnO film promotes the crystallization of silicon films. Decreasing the boron doping percentage contributes to the improvement of the properties of solar cells.