Abstract: Ultrasound treatment (UST) of poly-Si thin films on glass substrates is disclosed, for improving properties of such thin films for uses such in thin-film transistor applications. Hydrogenated films subjected to UST showed a strong decrease of the sheet resistivity. UST improves the electrical homogeneity of polycrystalline silicon as confirmed by spatially resolved surface photovoltage mapping. Spatially resolved photoluminescence and contact potential difference mapping confirmed that UST effect is grain boundary related. Studies of hydrogenated thin-film transistors demonstrated remarkable UST induced improvement in transistor characteristics, especially, a reduction of leakage current by as much as one order of magnitude and a shift of the threshold voltage. All these effects are believed to result from UST enhanced hydrogenation of dangling bonds at grain boundaries in polycrystalline silicon films.