A New Insulator for Thin-Film Transistor Backplanes and for Flexible Passivation Layers

摘要

Active-matrix organic light-emitting diode (AMOLED) displays will become the dominant technology for the next generation of flexible displays, due to their light weight and flexibility. Each pixel of an AMOLED needs a thin-film transistor (TFT) to drive the OLED. The large experience and manufacturing base of a-Si:H TFTs make their upgrade to AMOLED displays very desirable. AMOLED displays require diving TFTs that can source enough current to the OLED and must be stable enough for an OLED brightness half-life of 10 years. The TFT stability at low gate electric fields has been extended to a projected drive-current half-life of 1,000 years, by modifying the a-Si:H process [1], [2].The TFT stability at high gate fields has been raised by modifying the SiN_x gate dielectric [3, 4], A new gate dielectric material also has been found to be particularly stable against threshold voltage shift at high gate fields [5]. However, conventional a-Si:H/SiN_x TFTs have electron field-effect mobility μ of <1 cm~2/Vs [6]. Moreover, the deposition temperature of high quality SiN_x is over 250 °C, which limits its use to special plastic substrates [7]. We advance the art by introducing a new SiO_2-silicone hybrid gate dielectric deposited at room temperature for a-Si:H TFTs that raises the electron field-effect mobility μ_e to ~ 2.0 cm~2/V-s and the hole field-effect mobility μh to 0.1 cm~2/V-s [8].