Development of high quality polycrystalline silicon film is in strong demand for active matrix organic light emitting displays. In this study, AlCl3 vapor was applied to enhance the crystallization of amorphous silicon film. The crystallization of amorphous Si showed that round-shaped Si grains were nucleated from amorphous Si film and they impinged each other to form polyhedralshaped grains. The grain size in the crystallized Si film was very large and the surface roughness was very small. The field-effect hole mobility and subthreshold swing of the p-channel thin film transistor were 94 cm(2)/V s and 0.4 V/decade, respectively. The high performance of this thin film transistor is attributed to the large grain size, high crystallinity, and smooth surface of the poly-Si film crystallized in AlCl3 vapor. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3551573] All rights reserved.