A NEW TYPE POLY-Si PREPARED BY FAST LAMP ANNEALING OF Cat-CVD a-Si AND ITS DEFECT PASSIVATION BY HIGH PRESSURE WATER VAPOR ANNEALING

摘要

Nano-grain poly-Si (ngp-Si) films, which is a new type polycrystalline Si consisting of dense small grains with diameters of several ten nm, has been successfully fabricated by rapid thermal annealing (RTA) both for several ten seconds and for less than ten milliseconds. High pressure water vapor annealing (HPWVA) is found to be effective to terminate dangling bonds in ngp-Si films and can drastically decreases their defect densities down to the order of 10~(16) /cm~3. Silicon nitride (SiN_x) films deposited on a-Si films act to suppress desorption of hydrogen atoms during RTA, resulting in lowering the defect density of ngp-Si as well. An ngp-Si film annealed for several milliseconds indicates a minority carrier lifetime of 5-10 μs after HPWVA, showing the potential for high-efficient thin-film solar cell materials.