The Effect of Sn Dopant on the Electrical and Optical Properties of ZnO Thin Films

We study the electrical and optical properties of Sn-doped ZnO (SZO) films grown by DC-unbalanced magnetron sputtering. To study the electrical properties of the films, we perform current-voltage (I-V) measurement by using metal-semiconductor-metal configuration with Ag as a metal contact. The measurement is performed in the dark and under UV exposure condition to study the photodetection properties of the films. From the I-V curve, it shows that the sensitivity of SZO is dramatically enhanced compared to the undoped film. This enhancement is due to the role of Sn dopant, which gives more electrons to the system. Furthermore, UV-Visible spectra reveal that the band gap increase by introducing the Sn dopant. Photoluminescence spectra show SZO film exhibits a higher green emission intensity compared to ZnO film, which is related to the presence of oxygen vacancy. Our result is important to improve the functionality of ZnO for optoelectronic devices applications. (paper)