Defect States in Excimer-Laser Crystallized Single-Grain TFTs Studied with Isothermal Charge Deep-Level Transient Spectroscopy

摘要

Defect states were quantitatively evaluated in single-grain (SG) Si thin-film transistors (TFTs), prepared by micro-Czochralski (grain filter) process with excimer-laser crystallization, by means of isothermal charge deep-level transient spectroscopy with a high sensitive charge/voltage converter. Its sensitivity reaches 10"16 C and it operates in the range of 2 jxs - 10 ms. Measurements were performed on the SG-Si TFTs with various energy densities of laser crystallization, various channel areas, and positions in the grain. Our results indicate a direct correlation of fabrication parameters, parameters of the TFT determined from its transfer characteristics, and parameters of defect states (energy position in the band gap, concentration) induced by coincidence site lattice boundaries inside the location-controlled grains and by defects in the grain filter.