Optimization of crystallization energy density for excimer laser annealed polycrystalline silicon thin film transistors

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The excimer laser annealed (ELA) polycrystalline silicon thin film transistors (poly-Si TFTs) fabricated with different laser energy densities (EDs), ranging from 390mJ/cm2 to 510mJ/cm2, are investigated. It is found that, with the increase of the energy density, the grain size grows larger, the lifetime of minority carrier becomes longer, and the activation energy becomes lower. Poly-Si TFTs fabricated with higher energy densities hold better performance including larger field effect mobility (μFE) and on-state current (ION), and smaller threshold voltage (VTH), subthreshold swing (SS) and off-state current (IOFF). The optimized crystallization condition is from 470mJ/cm2 to 510mJ/cm2.