Growing Zn 0.90 Co 0.10 O Diluted Magnetic Semiconductors by r. f. Magnetron Sputtering
- PDF / 2,723,822 Bytes
- 6 Pages / 595 x 842 pts (A4) Page_size
- 1 Downloads / 202 Views
1201-H05-29
Growing Zn0.90Co0.10O Diluted Magnetic Semiconductors by r. f. Magnetron Sputtering Musa Mutlu Can1,2, Tezer Fırat1 and Şadan Özcan1 1 Hacettepe University, Physics Engineering Department, Beytepe, 06800, ANKARA, Turkey 2 University of Delaware, Material Science and Engineering Department, 19716, Newark, DE, USA ABSTRACT Zn0.90Co0.10O particles, synthesized by mechanical milling and thermal treatment, were pressed at 25 tons to form a 2” target for a radio frequency (r. f.) magnetron sputtering system. Using this target, thin films were deposited on (0001) oriented sapphire (α-Al2O3) substrates under 30W, 60W and 120W r. f. powers. Structural analyses of these films were done with X-Ray Diffractometer (XRD), Energy Dispersive X-Ray Spectrometry (EDS), XRay Photo Spectroscopy (XPS) and Atomic Force Microscopy (AFM). The ZnO films were deposited with (0002) preferred direction, which was coherent to (0001) ordered α-Al2O3. Impurity phases, such as Co clusters, CoO and Co3O4, were not detected with the surface analyses of Zn0.90Co0.10O thin films. Substituted Co atoms in the host ZnO matrix were identified by the binding energy peak of Co2p3/2, 781.3±0.4eV, and the energy difference of ~15.61±0.03eV between Co2p1/2 and Co2p3/2. These results also proved that there were no Co clusters or Co3O4 phases in the lattice. Homogeneity of Co atoms in the lattice was shown by EDS spectra. It was understood that the higher r. f. power caused the more homogeneous distribution of Co and Zn atoms in thin films. Distributions of Co and Zn on the film surface, deposited under 120W, were found as 8.1±0.1% (normalized atomic ratio) and 91.7±0.7% (normalized atomic ratio), respectively, and the surface roughness of thin film was demonstrated by AFM figures as 14.2±0.1nm. INTRODUCTION Oxide semiconductors (zinc oxide (ZnO), indium tin oxide (ITO) and cadmium oxide (CdO)) have gained importance in the last two decades due to their transparency in the visible region and their good electrical conductivity [1]. In addition to these properties, ZnO semiconductors have a wide band gap (3.3eV) at room temperature [2,3], a high reflective index [3] and a high piezo electrical constant [3]. These features make ZnO useful in the fields of photovoltaic cells, gas sensors, chemical sensors, transducers, pressure sensors and anti reflector coatings [2-4]. ZnO is also a well-known oxide semiconductor for research in diluted magnetic semiconductors. The main idea is to dope transition metals (V, Cr, Mn, Fe, Co, Ni and Cu) inside the ZnO lattice [1-5]. Magnetic behavior in the lattice is expected due to s-d and p-d hybridization [3 ,5] between the s and p levels of ZnO and the d level of transition metals. Molecular beam epitaxy (MBE), radio frequency (r. f.) magnetron sputtering, chemical vapor deposition (CVD), pulsed laser deposition (PLD), sol-gel and solid state reaction techniques have been used for thin film and bulk growing processes [3-6]. This study used a Zn0.90Co0.10O target which was synthesized by solid state reaction technique
Data Loading...
