Physical Origins and Analysis of Negative-Bias Stress Instability Mechanism in Polymer-Based Thin-Film Transistors

The physical origins of the negative-bias stress (NBS) instability in polymer-based thin-film transistors have been characterized. Through the quantitative analysis by TCAD simulation for the NBS time-dependent experimental results, the threshold voltage (V
_T
)-shift by sub-bandgap density-of-states redistribution forms 70% and 78% for the measured total V
_T
-shift while V
_T
-shift by gate oxide charge trapping only takes 30% and 22% at NBS time of 3000 and 7000 s, respectively. In addition, the increase of source/drain Schottky contact resistance (R
_SD
) is the main reason for NBS-induced on -current (I
_ON
) degradation.