Impact of repeated uniaxial mechanical strain on p-type flexible polycrystalline thin film transistors

Abstract

This letter investigates the effect of repeated bending of flexible p-channel low-temperature polycrystalline–silicon thin-film transistors employing an ultra-low-temperature process (<673 K). Experimental results reveal that interface state density (Nit) and grain boundary trap density (Ntrap) after 10 000 width-axis tensile strain bending iterations are more pronounced than after equivalent width-axis compressive strain bending. Extracted interface and grain boundary traps both increase, which elevate trap assisted leakage. Furthermore, the bending distorts the Si–Si bonds in the polycrystalline silicon (Poly-Si) film, which causes more significant negative bias temperature instability (NBTI) degradation because strain-induced weak Si–Si bonds can react with dissociated H during NBTI stress.