| 초록 |
Organic gate dielectric layers in thin film transistors (TFTs) of backplane for flexible displays have been developed because of their superior flexibility. However, organic materials have several disadvantages like low thermal and chemical resistivity. Furthermore, organic insulators have low dielectric constant leads to high threshold voltage of TFTs, which also occurs high power consumption. On the other hands, although inorganic gate dielectrics have high dielectric constant and low leakage current characteristics, they can be easily cracked under mechanical deformation. In order to maintain flexibility and high dielectric constant, therefore, it is essential to develop the hybrid insulator based on organic and inorganic materials. In this respect, we have fabricated organic/inorganic nanocomposite gate insulators and integrated them into flexible TFTs. To manufacture the nanocomposite gate insulators, polyimide (PI) was chosen as the organic material due to their high flexibility and good thermal stability. HfO2 nanoparticles (NPs) explored as inorganic materials for nanocomposite gate insulators. Nanocomposite gate insulators with varying ratio of HfO2 NPs concentration were prepared. In order to improve the characteristics of gate dielectric layers, we manufactured nano hybrid laminated structure using Al2O3 thin layer formed by atomic layer deposition (ALD). Electrical characteristics and physical stabilies are analyzed as varying the Thickness of Al2O3 layers. To analyze gate dielectric properties such as the capacitance, and leakage current characteristic, metal-insulator-metal (MIM) structures were prepared with organic TFTs during fabrication of devices. The output and transfer characteristics of organic TFTs after cyclic bending of 100,000 times indicated the improved mechanical stability of nanocomposite gate dielectrics. |
