ANALYSIS OF POLYCRYSTALLINE SILICON THIN FILMS WITH DIFFERENT GRAIN SIZE

摘要

Grain size of polycrystalline silicon (poly-Si) thin films fabricated by atmospheric pressure chemical vapor deposition (APCVD) can be controlled by an intermittent source gas supply method. An increase of grain size ( up to around 20 urn in our case) decreases the density of micro defects and dislocations, improving the crystalline order of the poly-Si thin films. We also tried to improve the crystalline order at the poly-Si grain boundaries or within the grain itself by a high temperature (750 ℃) annealing, which had pronounced effect on the peak position and FWHM of TO-BE peak in photoluminescence (PL) spectra. PL spectroscopy was shown to be a powerful method for investigation of the quality of polycrystalline Si thin films, but measurement of the Hall effect mobility has shown that this annealing temperature was too high. We then tried to characterize the samples annealed at lower temperatures (300℃) and compared the effects of different annealing atmospheres (hydrogen, water vapor).