This work investigates dynamic negative bias temperature instability (NBTI) in p-channel low-temperature polycrystalline silicon thin-film transistors (LTPS TFTs) with different rise and fall times. Experimental results reveal identical increases in the interface state density (N-it) induced by different dynamic NBTI stress conditions. Nevertheless, the degradation of the grain boundary trap (N-trap) becomes more significant as rise time decreases to 1 mu s. Because the surface inversion layer cannot form during the short rise time, transient bulk voltage will cause excess holes to diffuse into the poly-Si bulk. Therefore, the significant N-trap increase is assisted by this transient effect. (c) 2010 The Electrochemical Society. [DOI: 10.1149/1.3507253] All rights reserved.