Effects of ZnMgO buffer layer on structural, optical and magnetic properties of ZnGdO thin films grown by pulsed-laser deposition

• Main Authors: Tseng, Tzu-Lung, 曾子倫
• Other Authors: Fang-Yuh LO
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/96750853018517680812

碩士 === 國立臺灣師範大學 === 物理學系 === 105 === Pulsed-laser deposition was applied to grow gadolinium (Gd)-doped ZnO (Zn1-xGdxO) thin films on c-sapphire substrate. Gd concentration, substrate temperature, and laser energy fluence were varied, and the deposition rate, structural, optical and magnetic properties were investigated. In addition (Zn1-xGdxO/Zn0.9Mg0.1O) double-layer thin films were investigated for the effect of buffer layer. The relations between buffer layer thin film thickness and structural properties, optical properties of (Zn1-xGdxO/Zn0.9Mg0.1O) double layer thin films were studied. The oxygen partial pressure is 3×10-1 mbar. The Gd concentration is 1%, 3% and 8% . The deposition rate of Zn1-xGdxO increased with increasing laser energy fluence as well as with increasing Gd concentration. X-ray photoelectron spectroscopy showed the doping density is pretty close to nominal density. X-ray diffraction patterns and Raman-scattering spectra revealed Gd and Mg incorporation into ZnO without secondary phase. As Gd density increased, the grain size of Zn1-xGdxO thin films decreased, meaning that the thin film crystal quality decreased. As Zn0.9Mg0.1O thin film thickness decreased, thin films structural properties decreased, because the grain size of Zn0.9Mg0.1O thin film is limited by its thickness ── the grain size of thin film is close to its thickness. Photoluminescence (PL) spectroscopy showed that all the thin films had zinc interstitials and zinc vancancies. For (Zn1-xGdxO/Zn0.9Mg0.1O) double layer thin films, PL intensity was smaller than that of (Zn1-xGdxO) single layer. Magnetic investigations with a superconducting quantum interference device magnetometer revealed paramagnetism for all Zn1-xGdxO thin films.