ABSTRACTThin film hydrogenated Amorphous silicon (a-Si:H) was deposited on Molybdenum (Mo) substrates by d.c. glow discharge. We investigated the a-Si:H crystallization using four anneal techniques; nitrogen atmosphere furnace, vacuum, rapid thermal anneal (RTA), and excimer laser anneal. Anneal temperature ranged from 100 to 1200 °C. Excimer laser energy per pulse ranged from 90 to 340 M.J. Transmission electron Microscopy (TEM) revealed microstructure of crystallized Si film with grain size over 0.5 μm. X-ray diffraction (XRD) and Raman spectroscopy were employed to determine the degree of crystallization. The a-Si:H started to crystallize at temperatures over 600 °C. An 850 °C anneal reduced film resistivity to 10s (ω-cm) for intrinsic and 1 (ω-cm) for n-type. Coplanar type thin film transistors (TFT) with gate channel length of 25 μm and width of 220 μm were fabricated with various insulating layers; if sputtered SiO2, Si3N4, BaTiO3, MgO, and evaporated SiO. The first two exhibited the least leakage current. The as-grown intrinsic a-Si:H field effect mobility was around 0.03 (cmVV.s) and delay time was 5×10−7 s. The solid phase crystallized silicon film exhibited high leakage current. The delay time of an excimer laser anneal treated TFT was reduced to 2.5×10−7 s. Crystallized Si film mobility was improved to 15 (cm2 /V.s).
A Study on Selectivity and Temperature Coefficients of the Chloride Ion Sensors With RuOx Thin Film