Growth Of Polysilicon Films On Quaterz Substrates And Its Electronic Properties

The polycrystalline silicon(poly-Si) thin-films have many potential applications in the photovoltaic devices. The poly-Si thin films on the quartz glass substrate were grown by high-frequency chemical vapor deposition (HFCVD) and low pressure chemical vapor deposition (LPCVD), By changing the growth temperature, gas concentration, reaction time and pressure to grow poly-Si films with different thickness and quality, the grains size are 1～3μm. B-doped poly-Si films were grown in high temperature diffusion furnace, and their electrical properties were measured, the minimum sheet resistance is 100Ω/□by HFCVD, and after rannealing sheet resistance is 45Ω/□by LPCVD. The surface morphology and structured characterization of the poly-Si thin-films were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The result show that with increasing growth temperature, poly-Si thin-films grain sizes were increased, and its crystalline quality was improved, the test found, three crystal orientation appear <111>,<220>,<311>, the <111> orientation is the strongest. The gas concentration and growing pressure strongly effect to the growth rate of the poly-Si films. The electrical properties of doped poly-Si thin-films were tested by four-probe mete and Hall effet tester. Experimental results show that with increasing the diffusion temperature and time ,would lead to the poly-Si thin-films were recrystallized. also can reduce grain boundary defects and to activating impurities atoms. At the same time, increase of diffusion temperature and time would lead to many impurities into the poly-Si thin films, so that can reduce the poly-Si thin-films sheet resistance. We measure the light reflection ratio of poly-Si films, and studied the relationship between growth conditions or doping conditions of polycrystalline thin film and reflective properties. It was found that with the increase of growth and annealing temperature, the light absorption ratio of poly-Si films also get increased the least reflectivity is about 18.24% in 622nm.