Sm-doped ZnO thin films grown by pulsed-laser deposition

Yu-Tso Liao^1*, Jyun-Han Chen¹, Shi-Yu Liu¹, Hsiang-Lin Liu¹, Fang-Yuh Lo¹, Ming-Yau Chern²

¹Department of Physics, National Taiwan Normal University, Taipei, Taiwan
²Department of Physics, National Taiwan University, Taipei, Taiwan

* Presenter:Yu-Tso Liao, email:g0981229367@gmail.com

Samarium-doped zinc oxide (Sm:ZnO) thin films are grown by pulsed-laser deposition (PLD) on c-oriented sapphire substrates with Sm concentration ranging from 0 to 10 atomic percent. The oxygen partial pressure is 3x10^-1 mbar and the substrate temperature is 525°C during deposition. The structural, optical, and magnetic properties are reported.
X-ray diffraction (XRD) and Raman-scattering imply that Sm atoms are successfully incorporated into ZnO lattice. With increasing Sm content, the c-lattice constant decrease from 5.21 to 5.18 Å and the grain size decrease from 31.7 to 6.8 nm. Atomic force microscopy showed that all the samples having circular shape grain surface, and the surface roughness is between 22.4 and 3.6 nm. The optical properties investigated by transmission spectroscopy and ellipsometry. The results show that energy band gap increased with higher Sm doping, and the transmittance increase in UV region for Sm:ZnO. The magnetic properties investigated by SQUID show that 1 at.% doping Sm:ZnO film exhibiting ferromagnetic characteristics at low temperatures with ordering temperature lower than 150 K. Other Sm-doped ZnO thin films show only paramagnetic characteristics. Room-temperature magneto-optical Faraday effect spectra show only paramagnetic behavior from all Sm:ZnO thin films.

Keywords: Samarium doped zinc oxide, Pulsed laser deposition, Thin film