Effects of Mechanical Strain on Characteristics of Polycrystalline Silicon Thin-Film Transistors Fabricated on Stainless Steel Foil

The effects of uniaxial tensile strain on the performance of polycrystalline silicon thin-film transistors (poly-Si TFTs) is reported. Longitudinal strain increases the electron mobility and decreases the hole mobility, while transverse strain decreases the electron mobility and slightly decreases the hole mobility. Under longitudinal strain the off current decreases for both NMOS and PMOS TFTs and shifts in threshold voltage and substhreshold slope are observed for p-channel TFTs. A strong dependence on channel length for both electron and hole mobilities under longitudinal strain indicates the presence of a series resistance. For poly-Si TFTs, the mobility changes under strains are related to the strain effects on single crystalline silicon devices.