Magnetic properties of Er-doped ZnO films prepared by reactive magnetron sputtering

Abstract

All Zn 1−x Er x O (x = 0.04, 0.05, and 0.17) films deposited on glass substrates by radio-frequency reactive magnetron sputtering exhibit the mixture of ferromagnetic and paramagnetic phases at room temperature. The estimated magnetic moment per Er ion decreases with the increase of Er concentration. The temperature dependence of the magnetization indicates that there is no intermetallic ErZn buried in the films. The ferromagnetism is attributed to the Er ions substitution for Zn 2+ in ZnO lattices, and it can be interpreted by the bound-magnetic-polaron model.In semiconductor devices, one usually takes advantage of the charge of electrons. In contrast, magnetic materials are utilized on the basis of electron spin. In order to develop new electronics, it is necessary to combine both features. Diluted magnetic semiconductor (DMS) can serve as an avenue to utilize both charge and spin functions of electrons for various applications [1]. Many group IV [2], III-V [3], and II-VI [3] DMS materials have been obtained by doping magnetic impurities into semiconductors. Nevertheless, most of them have a low Curie temperature (T C ), which limits their [15]. Nevertheless, the magnetic properties of Er-doped ZnO materials have seldom been reported. In this paper, the magnetic properties of a series of Er-doped ZnO thin films are studied and the origin of FM is also discussed.The transparent Er-doped ZnO films were grown on glass substrates by radio-frequency (RF) reactive magnetron sputtering using Zn (purity: 99.99%) and Er (purity: 99.996%) together as targets. The sputtering chamber was evacuated by a molecular pump to a base pressure below 2 × 10 −5 Pa. During sputtering, the substrate temperature was kept at RT. Oxygen was introduced into the chamber as the reactive gas and the flow rate was controlled at 20, 25, 30, and 35 sccm, respectively. Additionally, argon was introduced into the chamber as working gas and its flow rate was regulated at 15 sccm. During the deposition, the chamber pressure and sputter power were fixed at 2.0 Pa and 5.3 W/cm 2 , respectively. The as-grown samples are denoted as Zn 1−x Er x O. Magnetic measurements were performed by vibrating sample magnetometer (VSM) and superconducting quantum interference device (SQUID), where the magnetic fields were parallel to the film planes. X-ray photoelectron spectroscopy (XPS) was used to analyze chemical valences and chemical compositions of the films.

Er-doped ZnO nanofibers for high sensibility detection of ethanol

“…Fig. 4(d) is the Er 4d XPS spectrum in the region of 168.8 eV, which reveals that Er ions are in a trivalent state in ZnO nanofibers [34,35]. These results indicate that Er is partially localized in the ZnO lattice and partially on the surface of nanofibers, in agreement with the results of EDS and HRTEM.…”

Intense violet–blue emission and paramagnetism of nanocrystalline Gd3+ doped ZnO ceramics

“…Paramagnetism is expected to arise from the exchange interaction of magnetic moments mediated by the defects in doped nanoceramics. Similar paramagnetic behavior was reported for transition metal doped ZnO and SnO 2 [29][30][31][32][33]. Adhikari et al [34] observed the absence of ferromagnetic and antiferromagnetic ordering in Gd doped SnO 2 nanoparticles.…”

Influence of oxygen partial pressure on the microstructural and magnetic properties of Er-doped ZnO thin films

“…In fact, room temperature ferromagnetism has been reported in Zn 1−x Er x O polycrystalline films prepared by radio frequency magnetron sputtering. 5 The researchers claimed that the ferromagnetism was due to the intrinsic properties of Er-doped ZnO films and could be interpreted by the bound magnetic polaron model (BMP). At the same time, Chen et al 6 proposed that Zinc vacancy (V Zn ) concentration and the Er clusters can jointly boost the ferromagnetism in the Zn 1−x Er x O thin films.…”