ENHANCED HYDROGENATION IN POLYCRYSTALLINE SILICON THIN-FILMS USING LOW-TEMPERATURE ULTRASOUND TREATMENT

Ultrasound treatment (UST) was applied to improve electronic propertie s of polycrystalline silicon films on silica-based substrates, A stron g decrease of sheet resistance by a factor of two orders of magnitude was observed in hydrogenated films at UST temperatures lower than 100 degrees C. This is accompanied by improvement of a film homogeneity as confirmed by spatially resolved photoluminescence study. The UST effe ct on sheet resistance demonstrates both stable and metastable behavio r. A stable UST effect can be accomplished using consecutive cycles of UST and relaxation. An enhanced passivation of grain boundary defects after UST is directly measured by nanoscale contact potential differe nce with atomic force microscope. Two specific UST processes based on interaction between the ultrasound and atomic hydrogen are suggested: enhanced passivation of grain boundary defects and UST induced metasta bility of hydrogen related defects. (C) 1996 American Institute of Phy sics.