Role of Bandgap States on the Electrical Behavior of Sequential Lateral Solidified Polycrystalline Silicon TFTs

The role of polycrystalline material properties on the electrical behavior of thin-film transistors (TFTs) is investigated through the temperature analysis of the transfer characteristics in the linear operation regime. The investigation is performed on devices fabricated on films that consist of long grains separated by parallel boundaries, crystallized using the sequential lateral solidification process. The study employed devices with channels aligned parallel and vertical to the boundaries' direction and on different film thickness. The temperature dependence of typical device parameters, such as the threshold voltage, the subthreshold swing, the mobility, and the leakage current, denotes the grain boundaries' influence on the electrical behavior. Their presence was found to determine the device performance through thermal activation. The results provide a more quantitative relation between the electrical properties of TFTs and the polycrystalline material properties.

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