Effect of Island Configuration and Neutral Axis Location for Mechanical Bending Strain on a-IGZO Thin Film Transistors

Abstract

The effect of electromechanical and mechanical strain was studied on amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistor regarding to the structural design of the device as well as the location from neutral plane (N.P) for bending stress. Here we show a highly reliable bending feature of the island structured (IS) device and its backplane against the mechanical strain after being subjected to an extreme tensile cyclic bending stress. The IS TFTs fabricated on polyimide (PI) substrate exhibit an pronounced bendability for an cyclic bending of 100,000 cycles with varying radii to a radius less than 2 mm with the electro-mechanical integrity. The onset of crack strain also closely corresponds to that of the electrical degradation of the device. The backplane array composed of IS TFTs clearly reveals that the island configuration remarkably reduce the bending stress accumulation on the sheets of inorganic stacked layers along to the uniaxial on plastic substrate.

Highly Bendable In-Ga-ZnO Thin Film Transistors by Using a Thermally Stable Organic Dielectric Layer

“…Recently, Park et al . demonstrated the flexibility down to 2 mm (corresponding bending strain is 2.5%) with a coplanar IGZO TFTs by adjusting the device structural design (island configuration) as well as its location at the neutral axis plane while being bent14. Thus far, the flexible TFTs based on AOSs have employed inorganic dielectrics, such as HfO 2 , ZAO, SiN X , and Al 2 O 3 12131516, as gate insulator layers due to their similar crystallinity to the AOS at the interface.…”