| AVS 58th Annual International Symposium and Exhibition | |
| Thin Film Division | Monday Sessions |
| Session TF-MoA |
| Session: | Emerging ALD Applications |
| Presenter: | Jaesang Lee, Hanyang University, Republic of Korea |
| Authors: | J.S. Lee, Hanyang University, Republic of Korea T.Y. Park, Hanyang University, Republic of Korea Y.B. Ko, Hanyang University, Republic of Korea H.Y. Jeon, Hanyang University, Republic of Korea J.G. Park, Hanyang University, Republic of Korea J.H. Ryu, Hanyang University, Republic of Korea H.T. Jeon, Hanyang University, Republic of Korea |
| Correspondent: | Click to Email |
Titanium dioxide (TiO2) has been regarded as one of the most promising photocatalysts for environmental protection because of its high photocatalytic activity, high chemical stability, low toxicity, and low cost. Anatase and rutile structures of TiO2 are two main phases with band gap energies of 3.3 and 3.1 eV, respectively. The structures of both anatase and rutile consist of chains of TiO6 octahedra. However, two crystal structures are obviously different. It is well-known that the difference in crystal structures causes different mass density (3.894 g/cm3 for anatase and 4.250 g/cm3 for rutile) and electronic band gap. The anatase phase has a more negative conduction band edge than that of the rutile phase. It results in superior photocatalytic activity of anatase phase than that of the rutile phase. Therefore, the structure of TiO2 films and high surface area are heavily important factors in photocatalytic efficiency.
In this study, TiO2 film was deposited by remote plasma atomic layer deposition(RPALD) and its phase formation temperature, impurity concentration, and chemical states of the were characterized by various analyses such as Auger electron spectroscopy (AES), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The TiO2 film was deposited on the flat Si substrate and vertically oriented Si nanowire by using remote plasma atomic layer deposition (RPALD) method. RPALD method has advantage to deposit thin film with uniform thickness on the 3-dimensional structure like vertically oriented Si nanowire. In addition, the RPALD method is possible to reduce damage by high energetic ion and to enhance the chemical reactivity between metal-organic precursor and reactant gas for deposition of high quality film. The vertically oriented Si nanowire was fabricated by Ar-annealing of Si substrate with Au nanocrystal at 1000 °C. And we have compared the photoluminescence (PL) features of these TiO2 films with these two different specific surface areas. We have found that TiO2 film deposited vertically aligned Si nanowire has higher PL intensity than that of TiO2 deposited flat Si substrate due to large area density of vertically oriented Si nanowire.