Impact of AC Stress in Low Temperature Polycrystalline Silicon Thin Film Transistors Produced With Different Excimer Laser Annealing Energies

This letter investigates degradation during alternating current (AC) operations in low-temperature polycrystalline silicon (LTPS) thin-film transistors (TFTs) produced using the selective excimer laser annealing (ELA). Different degrees of degradation, on-current increase and threshold voltage (V
_th
) shift were observed after AC operation stress in three devices with different ELA energies. Although a higher ELA energy device has a higher on-current, this will lead to higher protrusion and a stronger electrical field in the active layer. This stronger electrical field will cause serious electron trapping in the grain boundary trap (N
_trap
), leading to more serious degradation than that found in the lower ELA energy devices. Finally, COMSOL simulations and C-V measurements were executed to verify the physical mechanism.