Electrical characteristics and mechanical limitation of polycrystalline silicon thin film transistor on steel foil under strain

Abstract

This work investigates the effect of mechanical strain on the electrical characteristics of polycrystalline silicon thin film transistors (poly-Si TFTs). Poly-Si TFTs were fabricated on steel foil substrate and characterized under the strain ranging from −1.2% to 1.1% induced by bending. The electron mobility increased under tensile and decreased under compressive strain while that of the hole exhibited an opposite trend. For both n-channel and p-channel poly-Si TFTs, the threshold voltage decreased and the subthreshold slope increased under tensile strain, while the subthreshold slope was observed decreased under compressive strain. The off current of both types of TFTs decreased under tensile and increased under compressive strain. Poly-Si TFTs on steel foil failed at the tensile strain of 1.2% due to cracking of the channel material.