Optoelectronic modulation spectroscopy applied to the characterization of polycrystalline silicon thin film field effect transistors

Optoelectronic modulation spectroscopy has been applied to polycrystalline silicon thin film field effect transistors (poly-Si TFTs). Spectra include response from defect levels at the poly-Si grain boundary. According to the energy band structure of silicon, we can get three discrete defect levels of poly-Si grain boundary corresponding to the null positions of TFTS OEMS responses which have in phase to out of phase response if we assume the transition of electrons from defect levels to the /spl Gamma//sub 15/ CBM. The defect levels of poly-Si grain boundary illustrated in the energy band structure of silicon are 0.48, 0.24, and 0.08 ev below the /spl Delta//sub 1/ CBM, respectively.