IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Organic Films and Devices Thursday Sessions
       Session OF+TF-ThP

Paper OF+TF-ThP11
Optical Characterization of ZnO-CdO Thin Films Grown by Sol-Gel Method

Thursday, November 1, 2001, 5:30 pm, Room 134/135

Session: Aspects of Organic Films Poster Session
Presenter: T. Hata, Miyazaki University, Japan
Authors: K. Yoshino, Miyazaki University, Japan
T. Hata, Miyazaki University, Japan
H. Komaki, Miyazaki University, Japan
Correspondent: Click to Email
Wide bandgap oxide-semiconductors have attracted much attention for liquid crystal displays and solar cells. Recently, ZnO based materials are much respected for UV light-emitting devices. ZnO is a semiconductor with a large bandgap of 3.4 eV and a large excitonic binding energy of 60 meV. CdO is an also semiconductor with a direct bandgap of 2.3 eV and small indirect bandgap of 0.8 - 1.1 eV. The bandgap energy can be changed from 2.3 to 3.4 eV on ZnO and CdO mixed crystal. Moreover, although CdO is known to have a poor optical transmittance in the visible spectral region in comparison with those of ZnO films, CdO thin films are enough to be used for the window material for solar cells. Pure ZnO and CdO films have been studied many research groups. However, ZnCdO films have been few studied previously.In this work, ZnO-CdO thin films were grown by sol-gel dip coat method on glass and Silicon (Si) substrates at 100 ~ 600 °C under air atmosphere. The sol-gel technique is known to have the distinct advantages of process simplicity, lower cost and ease of composition control. Precursor solutions of ZnO-CdO are prepared by dissolving both 5 wt.% zinc acetate dihydrate and 5 wt.% cadmium acetate dihydrate into anhydrous ethanol for the solutions to have the desired Cd/Zn at.%. Poly-ZnO and -CdO thin films are obtained on the glass substrate more than 500 ¡C and 200 °C, respectively. A value of full width at half maximum of (100) peak at the XRD spectra become small with the increasing the growth temperature. By using the Si substrate (100) instead of the glass substrate, poly-ZnO and -CdO thin films have (100) orientation. Moreover, an optical transmittance and bandgap energy of the Zn@sub X@Cd@sub 1-X@O thin films decrease nonlinearly with the decreasing X values.