Kim Jin Soo, Cho Sung Won, Kim Ii, Hwang Byeong Ung, Seol Young Gug, Kim Tae Woong, Lee Nae-Eung
J Nanosci Nanotechnol. 2014 Nov;14(11):8596-601. doi: 10.1166/jnn.2014.10014.
To develop physically flexible electronics, high performance and mechanical stability of component materials and devices are required. For a flexible display, a backplane with flexible thin-film transistors (TFTs) must be developed. Gate insulating materials with excellent electrical and mechanical properties are highly important to the development of flexible TFTs. We investigated nanocomposite gate dielectrics composed of polyimide (PI) because of their superior thermal stability, as well as different inorganic HfO2, TiO2, and Al2O3 nanoparticles with high dielectric constants. Nanocomposite gate dielectrics of HfO2 nanoparticles and PI lowered leakage current density and increased the relative dielectric constant compared to PI solely because of a high degree of dispersion. Pentacene TFTs with HfO2 nanocomposite gate insulators also showed higher field-effect mobility (μ), smaller subthreshold swing, and an enhanced on/off current ratio (I(on/off)) compared to those of the PI gate dielectric. In addition, mechanical cyclic bending tests involving bending cycles of 2 x 10(5) time sat a bending radius of 5 mm showed improvement in electrical stability of nanocomposite gate insulators with a change in leakage current density of nanocomposite gate insulators below 30%.
为了开发具有物理柔韧性的电子产品，需要组件材料和器件具备高性能及机械稳定性。对于柔性显示器而言，必须开发出带有柔性薄膜晶体管（TFT）的背板。具有优异电气和机械性能的栅极绝缘材料对于柔性TFT的开发至关重要。我们研究了由聚酰亚胺（PI）组成的纳米复合栅极电介质，因为它们具有卓越的热稳定性，以及具有高介电常数的不同无机HfO2、TiO2和Al2O3纳米颗粒。与仅使用PI相比，HfO2纳米颗粒和PI的纳米复合栅极电介质由于高度分散，降低了漏电流密度并提高了相对介电常数。与使用PI栅极电介质的并五苯TFT相比，具有HfO2纳米复合栅极绝缘体的并五苯TFT还表现出更高的场效应迁移率（μ）、更小的亚阈值摆幅以及更高的开/关电流比（I（on/off））。此外，在弯曲半径为5mm的情况下进行2×10（5）次弯曲循环的机械循环弯曲测试表明，纳米复合栅极绝缘体的电稳定性有所改善，纳米复合栅极绝缘体的漏电流密度变化低于30%。
