Flexible, Lightweight Steel-Foil Substrates For a-Si:H Thin-Film Transistors

Abstract

For many flat panel display applications, traditional glass substrates for the TFT backplane are not sufficiently rugged. Therefore, we have begun to explore the use of steel foils as TFT substrates for emissive or reflective displays. We report the fabrication of high quality a-Si:H TFTs on lightweight, flexible 75 μm thick stainless steel foils. The electrical characteristics of the TFTs were good and were not significantly affected by either dropping over 15 meters to a concrete floor or being bent to a radius of curvature of 8.25 cm for a period of over 400 hours. Typical device characteristics were: I_ON/I_OFF > 10⁷, I_OFF ∼ 10¹² A, V_T ∼ 3.2 V, and μ_EFF ∼ 0.9 cm²/Vs. We also discuss our recent work on the successful integration of organic light-emitting diodes (OLEDs) with TFTs on steel substrates, resulting in a new form of emissive display.