Unified extraction method for amorphous and polycrystalline TFT above threshold model parameters

Abstract

A unified procedure is presented to extract above-threshold model parameters in polysilicon and a-Si:H TFTs. It is based on the integration of the experimental data current, which has the advantage of reducing the effects of experimental noise. This method is applied to the linear and saturation regions for the above-threshold regime and allows the extraction of all the above-threshold parameters. We already presented a similar method applied to a-Si:H TFTs. In this work it is demonstrated that in the above-threshold regimen the mobility of polysilicon TFTs can be modeled also as a function of the gate voltage to the n power and a similar integration procedure can be used to extract the device modeling parameters. The unified extraction procedure provides in addition the possibility of monitoring the crystallization process of a-Si:H TFTs into polysilicon, which has become a widely used process of fabricating low temperature polysilicon TFTs. The process of polycrystallization manifests itself by a variation and change in sign of one of the model parameters. Extracted parameters can be introduced in AIMSpice circuit simulator for device modeling. The accuracy of the simulated curves using the extracted parameters is verified with measured.