Effect of mechanical stress on the performance of an a-Si:H TFT on plastic substrate

In this paper we describe the effect of mechanical stress on the performance of an a-Si:H TFT (Thin Film Transistor) on plastic substrate. We fabricated an a-Si:H TFT array of BCE (Back Channel Etched) structure with 2 layer gate insulators on plastic substrates. The performance of an a-Si:H TFT on plastic was measured under uniaxial compressive and tensile stresses as a function of curvature. Bending was parallel to the source-drain current path. The radius of bending was varied from 25 mm to 5 mm. The electrical characteristics of a-Si:H TFTs on PES (Polyethersulfone) were measured under bending inward and outward. No changes in the leakage current and subthreshold slope were found. However, the field effect mobility and threshold voltage degraded and could be plotted as a function of 1/R until the sample was cracked by the high stress.