| dc.description.abstract | In this study, the intrinsic hydrogenated amorphous silicon (a-Si:H) thin films deposited on the textured silicon substrate for application in heterojunction with intrinsic thin layer (HIT) solar cell was prepared by Plasma Enhanced Chemical Vapor Deposition (PECVD). The passivation quality of a-Si:H thin films was investigated by modulating the process parameters such as power, distance, dilution ratio, and substrate temperature. During the process, OES (Optical emission spectrometer) was used to diagnose the variation of plasma species, and QMS (Quadrupole mass spectrometry) was utilized to determine the concentration of free radicals in plasma. We changed different method of wafer cleaning to improve the interface between substrate and thin film. The thickness and the characteristics of thin film were measured and further analyzed by Spectroscopic Ellipsometer. The surface passivation quality of thin film was determined by photo-conductance lifetime tester. We also used annealing treatment to further improve the structure of a-Si:H thin films.
The results show that integrated QMS and OES is indeed a way to help us to analyze the mechanism of plasma, and by adjusting the process parameters, the property of amorphous silicon (a-Si:H) thin films is determined. A high passivation quality of a-Si:H thin films on the textured silicon substrate was obtained under the conditions of H2/SiH4=7.3, power of 30W, working pressure of 300mtorr , substrate temperature of 300℃,and appropriate wafer cleaning. The effective lifetime of a-Si:H film increased to 690 μsec, the implied Voc increased to 0.69 V and the surface recombination velocity (SRV) was also reduced to 12 cm/s. | en_US |