| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2014) | |
| Thin Films | Wednesday Sessions |
| Session TF-WeP |
| Session: | Thin Films Poster Session |
| Presenter: | YoonHo Jung, Yonsei University, Republic of Korea |
| Authors: | Y.H. Jung, Yonsei University, Republic of Korea H.-G. Park, Yonsei University, Republic of Korea H.-C. Jeong, Yonsei University, Republic of Korea D.-S. Seo, Yonsei University, Republic of Korea |
| Correspondent: | Click to Email |
Oxide thin-film transistors (TFTs) have been actively studied to this day and suggest the promising technique with carbon nanotube, nanowire, nanoparticle, or small molecules. Oxide TFTs are made of metals that have sufficiently large ns orbitals to overlap with each other. Thus, they can transport charge carriers without being sensitive to the crystalline structure. An advantage of these devices is that they can be conductive even when the material is in an amorphous phase. With this technique, solution processing is a useful method for generating amorphous oxide TFTs. In addition to its low manufacturing cost, easy deposition, and simple procedure, this method is important because of its outstanding synthesis capacity. With this method, each material can be simply mixed, and uniform films can be formed to achieve multi-component systems. Thus, this property is essential for making oxide films that consist of more than two materials.
Among a variety of solution-processed oxide TFTs, InGaZnO TFTs are the most widely used materials. In InGaZnO TFTs, Ga suppresses carriers and suppression of carriers is achieved by increasing the number of oxygen vacancies. Oxidization of the material is highly related to an electronegativity and a lower electronegativity increases the tendency to be oxidized. In this study, we chose yttrium because the electronegativity of Y is 1.2 which is much lower than that for Ga. Therefore, more oxidization occurs in the channel lattice, which leads to additional suppressing oxygen vacancies.
Azobenzene is a small organic molecule that has been frequently used for organic TFTs. Furthermore, the photo-induced isomerization of azobenzene is an interesting property. In each phase, which is trans- or cis-phase, the molecular structure is different. Normally, the molecule remains in the trans-phase because of higher stability. When exposed to an appropriate light source, azobenzene changes into the cis-phase.
Herein, we investigated solution-processed amorphous InYZnO with azobenzene channel TFTs. The effects on the electrical and structural characteristics of TFT channels due to the photo-induced isomerization of azobenzene were analyzed using a field effect-scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), and electric characteristic analysis.