Thesis (M.Sc.)--Chulalongkorn University, 2011

The Schottky barrier diodes and piezoresistive strain sensor were fabricated by using plasma polymerized polypyrrole. The polypyrrole was prepared by using plasma at AC voltage in the range of 800-1400 volt and reaction time for 30-90 min. The polypyrrole film was characterized by spectrophotometry and the functional groups of polypyrrole film were identified by Fourier transform infrared spectroscopy (FTIR). The FTIR confirmed that the polypyrrole was successfully obtained. The morphology of polypyrrole film was observed by Scanning electron microscopy (SEM) that shows dense, smooth, and uniform film. The thickness of polypyrrole films were in the range 1.02-2.60 µm. The suitable condition for Schottky barrier diode fabrication was in-situ doped by I2 under low voltage and less reaction time. For the fabrication of piezoresistive strain sensor, polypyrrole film was prepared by plasma on polymethyl methacylate substrate. The product shows flexible property. Piezoresistivity is quantified by the gauge factor. The sensor was fabricated by polypyrrole at 800 volt for 30 min which led to the highest gauge factor.