Effect of ethylene glycol incorporated dielectrics on characteristics of solution-processed oxide thin film transistors

Abstract

Metal oxide semiconductor (MOS) have been studied as an active layer for thin film transistors (TFTs) due to their advantages such as high mobility, uniformity, and transparency. The silicon-based semiconductor TFTs such as amorphous Si TFT and low temperature poly silicon (LTPS) TFT have some disadvantages and obstacles, but metal oxide semiconductor TFTs have unique merits differently with them. Applications of oxide semiconductor TFTs can be applied in high-resolution AMLCD TFT back-plane, large area AMOLED, flexible display, and transparent display. The electrical properties of TFTs have been improved to meet demands of industry such as higher definition, faster operating speed, and low-voltage operation. In a kind of effort to meet demands, various metal oxide semiconductor materi-als have been studied and demonstrated. New compositions such as In-Zn-O, In-Ga-Zn-O, and cation- or anion- doped oxide, and new process such as aqueous solution route, fuel-induced thermal annealing were studied. However, the improvements by new design of oxide semiconductor material have the limi-tation. In addition to MOS, the gate dielectrics are also essential component in thin-film transistor. Gate dielectrics always are contacted with semiconductor materials and critically affect the electrical proper-ties of semiconductors. Requirements of gate dielectrics can be low leakage current, wide band gap, good interface quality, compatibility with semiconductor materials, and thermodynamic stability. $SiO_2$ is most famous and used gate dielectric, but it have low dielectric constant (~3.9). High-k dielectric constant (high-k) materials are widely studied for continuing the scaling trend of metal-oxide-semiconductor field effect transistors (MOSFETs) to replace SiO2. Generally, the high electrical capacitance of gate dielectrics with a high dielectric constant (k) can induce some advantages such as a low operating voltage, and a high on-current level in thin-film transistor dev...