Trap properties of asymmetrical double-gate polysilicon thin-film transistors with low frequency noise in terms of the grain boundaries direction

Low frequency drain current fluctuation noise was measured in two types of polysilicon double gate thin film transistors fabricated by sequential lateral solidification technique keeping the back gate grounded. In X-oriented devices, the grain boundaries are parallel to the drain current flow, while in Y-oriented devices the grain boundaries are lying perpendicular to the drain current flow. The noise spectra consist of generation-recombination (g-r) and flicker noise components. In X-oriented TFTs the g-r centers are related to bulk traps located in the grains, whereas in Y-oriented TFTs the g-r centers correspond to grain boundary traps in addition to bulk traps in the grains.