On the mobility, turn-on characteristics and activation energy of polycrystalline silicon thin-film transistors

Abstract

In the present paper we propose a turn-on current model of polycrystalline silicon thin-film transistors (poly-Si TFTs). It is found that at low as well as at high doping concentrations, effective carrier mobility ( μ eff) increases with increase in temperature whereas a dip is observed at intermediate doping concentration. At very high and very low doping concentration the effect of temperature on the mobility is found to be almost negligible. Calculations reveal that effective carrier mobility and drain current increases as the gate bias increases and are larger for a lower trap state density. The calculated value of activation energy decreases as the gate bias increases and is larger for a larger poly-Si inversion layer thickness. A fair agreement is observed between the present predictions and the experimental results.