Effect of mechanical strain on mobility of polycrystalline silicon thin-film transistors fabricated on stainless steel foil

Abstract

The effect of uniaxial tensile strain parallel to the channel on mobility of polycrystalline silicon thin-film transistors (TFTs) on stainless steel foil has been investigated. The electron mobility increases by 20% while the hole mobility decreases by 6% as the strain increases to 0.5%, and both followed by saturation as the strain increases further. The off current decreases for both types of TFTs under strain. All TFTs remained functional at the applied strain of 1.13%.

Hole-mobility-limiting atomic structures in hydrogenated amorphous silicon

“…We see that while both stress states express strong correlations between hole trapping and the localization of the hole, the tensile ensemble shows (1) longer localization lengths than the unstressed ensemble, indicating that tensile stress is indeed allowing delocalization; and (2) that the hole trap depth becomes more dependent on the localization length when tensile stress is applied, seen through the higher slope (4.4 meV/Å), confirmed to 99% confidence, as well as the +1 GPa peak (black) remaining nearly uniformly above the unstressed ensemble (blue). These effects, combined with the rapid increase of hydrogenated voids in our experimental samples, begin to explain why we obtain a sharp decline in hole mobility of our films with increasing tensile stress, as well as agreeing with previous experiments measuring decreased hole mobility under applied stress in polycrystalline films [37].…”

Effect of bias stress on mechanically strained low temperature polycrystalline silicon thin film transistor on stainless steel substrate

“…2 Previous researchers have reported the effect of tensile strain on the mobility of poly-Si TFTs. 3 However, no further investigation was reported for the influence of bias stress on the mechanically strained poly-Si TFT devices. In this work, therefore, we study the effect of bias stress on the variations in threshold voltage, mobility, and trap density for the p-channel poly-Si TFT under uniaxial compressive and tensile strain induced by substrate mechanically bending.…”

Behavior of the parameters of microcrystalline silicon TFTs under mechanical strain

“…The electron mobility of a-Si:H TFTs was found to increase with tensile stress and to decrease with compressive stress. The electron mobility increases with tensile stress [10] and the hole mobility decreases under the same tensile stress [10,11] for LTPS TFTs. These results are limited particularly when it comes to crystallized silicon TFTs.…”

“…Group [7][8][9]. It is possible to find also some papers on the mechanical behavior of crystallized silicon TFTs mainly on LTPS TFTs fabricated on metal foils [10][11][12]. The electron mobility of a-Si:H TFTs was found to increase with tensile stress and to decrease with compressive stress.…”