Characterisation and modelling of polysilicon thin-film transistors

The characteristics of laser recrystallised polycrystalline silicon TFTs have been analysed, by combining electrical measurements and 2-D simulations using TMA-MEDICI. It is found that, in addition to the density of states, accurate knowledge of the minority carrier lifetime is necessary to simulate the output characteristics. Furthermore, our results confirm that the leakage current is due to thermal generation at low V-DS and to phonon-assisted tunnelling at high V-DS. Poole-Frenkel barrier lowering must be included in the treatment of the latter in order to produce accurate simulations. Finally, the accuracy and good convergence of our circuit simulator, which includes frequency and bias dependent nodal capacitances, is also demonstrated.