Study On The Laser Crystallization Of Intrinsic Amorphous Silicon Thin Films

At Present, The dominating used energy in the world is mainly non-renewable energy such as oil,natural gas, and coal. According to the current calculated discovered reserves and consumption, theseenergy sources can only last about150years. In addition, overdevelopment and utilization is one of themain reasons for deteriorating Human survival environment, for example, the released gas includingCarbon dioxide and oxygen sulfide results global warming and generation of acid rain. thus, the need foradjusting energy structure is urgent. In the21st century, human face dual challenges of economic andsocial sustainable development, developing the global economy with the limited resources and therestriction of the requirements of environmental protection is now a hot issue, This requires that thealternative energy sources must be renewable clean energy. Solar energy is a clean, efficient andeverlasting, which complies with the requirement and is at an advantage. Solar energy photovoltaic powergeneration is the essential method for utilizing the sun’s radiation energy, the principle of which isproducing solar cells by the photovoltaic effects of materials. Since the advent of solar cells, silicon is themain materials for the cell’s research and development, as for the advantages: High storage capacity,mature manufacture technology, no pollution, the high conversion efficiency, good stability. Silicon-basedsolar battery mainly includes crystalline silicon and silicon thin film.Crystalline silicon solar battery hashigh photoelectric conversion efficiency and mature technology, but the demand for the purity of rawmaterials is strict and the production process wastes a lot. High purity crystalline silicon preparationprocess is complex and belongs to high pollution industry, the everlasting producing cost goes againstpopularization and application of Photovoltaic power generation technology. Silicon thin film solar cell can utilize silicon effectively, which helps reduce the cost, but the shortcoming is that the generally vacuumtechnology growth of silicon thin film generates amorphous silicon, which has a low photoelectricconversion efficiency and exists "Steabler-Wronski effect". In order to improve the efficiency, we mustcrystallize the amorphous silicon thin films, and the higher the degree of crystallization is, the better theuniformity is,the higher the efficiency of the battery is. The general thermal annealing crystallizationtechnology can’t achieve ideal crystallization effect because of the inferior temperature resistance of glassbase and also can’t realize the quickly production of solar cell for the slow crystallization speed (generallytake hours). Then, using the high energy of laser to achieve quick uniform crystallization effect becomesthe promising crystallization method.This paper mainly study laser crystallization of the silicon layer in silicon-based film solar cells.Because the purity of amorphous silicon thin film has a big impact to the laser crystallization effect, thecrystallized source adopted the intrinsic silicon layer. first we deposited amorphous silicon thin film inordinary glass substrate by PECVD, then explored the crystallization process and method of amorphoussilicon thin films, adopting the continuous laser and pulse laser for crystallizing samples respectively topolycrystalline and even Single crystal,thereby weakening the "S-W effect "and improve the filmperformance overall. After the crystallization, representing the crystallization effect through the confocalmicroscopy Raman test technology and surface morphology by scanning electron microscopy. Testing theamorphous silicon thin film absorption spectrum by Uv-vis near infrared spectrophotometer and electricalproperties by hall tester. Calculating some important parameters through the corresponding formula aftercrystallization and achieve purpose of optimizing the crystallization process parameters.