Investigation On The Preparation And Properties Of Microcrystalline Silicon Thin Film

Recently, with the rapid development of solar photovoltaic technology , the microcrystalline silicon thin films without s-w effect has been internationally recognized as a new generation of silicon-based film solar cells materials because of its great potential of efficiency improving and lowercost.In this thesis, the amorphous silicon thin-films were deposited by PECVD, and the microcrystalline silicon thin-films were obtained by rappid thermal annealing. The influence of different deposition parameters and annealing parameters on amorphous silicon thin-films was studied detailedly.Firstly, the effect of different deposition parameters (hydrogen diluted concentration, deposition temperature, glow power, deposition pressure and the total gas flow rate) on deposition rate, the crystallization of electrical properties and microstructure of amorphous silicon thin-films were studied. The reason of the variation of deposition rate, the crystallization electrical properties and microstructure were analyzed,and the best deposition parameters for microcrystalline silicon thin films were also obtained.Secondly, the influence of different annealing parameters (annealing temperature, annealing time and annealing rate ) on the crystallization effects of amorphous silicon thin-films were also studied. The reason was also analyzed.The regularity of optimizing microstructure The optimized anneal technology of microcrystalline silicon thin film were acquired.The experimental results showed that, the crystallization effect of films was poor with the increase of hydrogen diluted concentration.When the hydrogen diluted concentration is 96%,the microcrystallization silicon thin film was accorded with device demanded because light conductivity is higher two orders of magnitude than dark conductivity.With the increase of deposition temperature,the deposition rate increased gradually.However,when the deposition temperature arrived 400℃,the rate dropped,so the optimal deposition temperature was 350℃.With the increase of power, the crystallization becomed better and better, the biggest was at 70W,but become smaller at 100W.With the increase of deposition pressure,the film transformed from amorphous to microcrystal,but when the pressure was 3 Torr,the film was turned into amprphous.It is suggested that high pressure will destroy the transformation from amorphous to microcrystal. With the annealing temperature rised from 700℃to 900℃, amorphous shifted gradually to microcrystal.It is indicated that the annealing temperature affects directly the crystallization of films. As the annealing time extended from 50s to 110s, the crystallization degree increased gradually. The experiment results also showed that the crystallization degree was good, when the heating rate of annealing was faster.The crystallization degree was poor ,when the crystallization degree was poor.