Drain voltage sweeping-induced degradation in n-type low-temperature polysilicon thin film transistors

Abstract

Device degradation under the drain voltage (Vd) sweeping, where Vd lineally sweeps at a fixed gate voltage, has been investigated for n-type low-temperature (LT) polysilicon thin film transistors (TFTs). The degradation mechanism is found to be related to the dc hot carrier (HC) effect even for a sweeping time as short as ∼µs. Since a routine device output measurement can induce significant (as large as 30%) on-current (Ion) degradation in such LT crystallized TFTs, only by using the optimized pulse IV method can one obtain an accurate output measurement without much affecting the device under test (e.g., <0.5% of Ion degradation).