| 학회 | 한국재료학회 |
| 학술대회 | 2013년 가을 (11/06 ~ 11/08, 제주롯데호텔) |
| 권호 | 19권 2호 |
| 발표분야 | A. 전자/반도체 재료(Electronic and Semiconductor Materials) |
| 제목 | Electronically Tuned Nanostructured TiO2 and ZnO |
| 초록 | The nanoscale and nanostructured TiO2 and ZnO have been highlighted over the last decade since revealing the great optical functionality for energy and optoelectronic devices such as the absorber in the dye sensitized solar cell, ultra violet (UV) emitter and sensors, and photocatalyst. The nanostructure of these materials offers the great enhancement of surface/interfacial area against bulk type so that the photo-generated carriers can be efficiently transferred at the heterojunction. Nevertheless, due to its native defect associated intrinsic n-type property, it is very challenging to tune systematically electronic properties of oxides with post-doping process as done for silicon. However, the delicate tuning of electronic and optical properties in nanoscale metal oxide materials becomes more important for recent energy/optoelectronic device applications. In this presentation, I will report our recent research outcomes on electronic and optical tuning of nanostructured TiO2 and ZnO for energy and electronic device application. First, the high n-type doping of TiO2 is achieved by F-doping or insertion. The low energy F ion was incident on tens of nm scale TiO2 thin films and about ~ 10% F was introduced to TiO2 surface in depth of 4 nm. As a result, the Fermi energy level is up-shifted toward conduction band and conductivity was improved by a factor of 40. All these effects were explained by interstitial F interaction to surface O-vacancy site, a native n-type donor. In other way, C-doping to TiO2 nanotubes was also studied and in this case, the remarkable bandgap narrowing from 3.3 eV to 1.7 eV due to the interstitial C bond to Ti-O bond is resulted to show the significant visible light absorption increase by 350% over the undoped. Secondly, the 3 dimensional hierarchical ZnO structure was produced by atomic layer deposition (ALD) aiming the exact electronic band structure tuning for application of UV sensors. Depending on the structure morphology (i.e., either sheet or rod) formed by colloidal synthesis, there is a significant variation of electronic structure. Using ALD, we could fabricate the nanosheet-nanorod complex with electronic band structures outside limit of wet synthesis chemistry. In another example of study to enhance the visible absorption in ZnO nanorod, the local surface plasmon was utilized by metallic RuOx nanoparticle ALD process. This leads to the visible absorption increase by a factor of 3. |
| 저자 | 서형탁 |
| 소속 | 아주대 |
| 키워드 | metal oxide; bandgap; electronic structure; visible absorption |
