Fabrication Of Hydrogenarated Amorphous Silicon Thin Films By PECVD And The Study Of Metal Induced Crystallization

As we know, it is expensive to fabricate crystal silicon solar cells and polysilicon solar cells. Therefore the silicon films and the silicon films solar cells have been concerned in the field of PV. Compared with crystal silicon solar cells and polysilicon solar cells, the silicon-based film solar cells consume less silicon materials and the cost is much lower, especially, the application of low-cost substrates makes it more competitive in cost-control. Presently, the silicon-based film solar cells can be divided into amorphous silicon thin film solar cells and micro-crystalline /poly-crystalline thin film solar cells. Amorphous silicon thin film solar cells have more advantage in silicon-based film solar cells as following: the low deposition temperature, easy to fabrication in large area, convenient to apply integrated technology. To lower the cost of fabrication of poly-crystalline silicon material is the key to control the cost of poly-crystalline thin film solar cells. So seeking a method of preparation polysilicon which is low energy consuming, low cost is concerned.In this paper, we study the deposition rate of amorphous silicon film by change the ratio of H₂/SiH₄, the gas pressure in the chamber, the radio frequency (rf) power and the temperature of substrate by plasma enhanced chemical vapor deposition (PECVD).we also investigated the optical character of the amorphous silicon. It indicated that with the increase of the ratio of SiH₄/H₂, the temperature of the substrates, the gas pressure and the rf power, the deposition rates increased. The absorption coefficient of the intrinsic amorphous silicon material varied between 4.5×10⁴ cm^-1─8.5×10⁴ cm^-1.We also fabricated amorphous silicon film solar cells and analysed the character of the amorphous silicon we fabricated in theory. The model of amorphous silicon thin film solar cells we set indicates that the contamination of oxygen have a serious effect on the improvement of the performance of amorphous silicon thin film solar cells.Polysilicon materials were fabricated by metal induced crystallization of amorphous silicon in order to seek a low cost method to fabricate polysilicon. Firstly we study the aluminum induced crystallization of amorphous silicon assisted by transverse electric field. The results indicated that transverse electric field is beneficial to aluminum crystallization of amorphous silicon. With the increasement of the intensity of transverse electric field, the effects of crystallization of amorphous silicon enhanced. With the increasement of annealing time and annealing temperature, the effects of aluminum induced crystallization of amorphous silicon assisted by electric field were enhanced. The crystallization temperature can be lowered to 400℃by aluminum induced crystallization of amorphous silicon assisted by transverse electric field. We also investigated silver (Ag) induced crystallization of amorphous silicon. The results indicated that the crystallization of amorphous silicon induced by silver can happened at 530℃if heated Ag/a-Si compound film for an hour; at 550℃if heated Ag/a-Si compound film for 30 min.