Field-effect conductance activation energy in an undoped polycrystalline silicon thin-film transistor

Abstract

We investigate the temperature dependence of the field-effect (FE) conductance of thin-film transistors on undoped polycrystalline silicon layers. The FE conductance is thermally activated at a fixed gate voltage. The conductance prefactor G0 increases exponentially with the FE activation energy Ea, in accordance with the Meyer–Neldel rule. Using these results, a model of exponentially decaying band tails explains the FE activation energy data. By fitting the FE activation energy data with the theory, we determine the trap distribution in polysilicon layers deposited at various pressures. The results indicate that the existence of band tails is not an intrinsic property of grain boundaries.