Origin of Degradation of Flexible Poly-Si TFTs Under Dynamic Bending Stress

Abstract

Degradation of flexible low-temperature poly-Si TFTs under dynamic bending stress is studied in controlled ambient of different kinds. It is demonstrated that synergistic effect of H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O vapor and O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is the origin of the positive threshold voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> ) degradation of poly-Si TFTs under dynamic bending stress in the air ambient, while the dynamic bending stress alone does not cause any TFT degradation. The degradation is found to strongly depend on the ratio of O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> to H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O vapor in the ambient. A degradation model of “H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O and O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> assisted electron transport and capture” is proposed, which is based on the participation of both reactants in reactions with dangling bonds along the micro-/nano- cracks penetrating through the passivation layer into the active region of TFTs, formed under the dynamic bending stress.