Ti-doped ZnO Thin Films Prepared at Different Ambient Conditions: Electronic Structures and Magnetic Properties

Abstract

We present a comprehensive study on Ti-doped ZnO thin films using X-ray Absorption Fine Structure (XAFS) spectroscopy. Ti K edge XAFS spectra were measured to study the electronic and chemical properties of Ti ions in the thin films grown under different ambient atmospheres. A strong dependence of Ti speciation, composition, and local structures upon the ambient conditions was observed. The XAFS results suggest a major tetrahedral coordination and a 4+ valence state. The sample grown in a mixture of 80% Ar and 20% O2 shows a portion of precipitates with higher coordination. A large distortion was observed by the Ti substitution in the ZnO lattice. Interestingly, the film prepared in 80% Ar, 20% O2 shows the largest saturation magnetic moment of 0.827 ± 0.013 µB/Ti.

Ferromagnetism in Ti-doped ZnO thin films

“…The coercive field is about 100 Oe at 300 K and increases to 233 Oe when the temperature is lowered to 100 K. The magnetic moment is surprisingly high. It is significantly higher than that reported by Venkatesan et al 13 and Antony et al 20 (0.15 l B /Ti at room temperature in 5% Ti-ZnO) and consistent with that reported by Yong et al 21 (0.82 l B /Ti at room temperature in 0.6% Ti-ZnO). To put these numbers in perspective, let us compare the magnetic moment of these films with that measured in our Mn-doped ZnO films grown in the same vacuum chamber and measured in the same magnetometer.…”

“…To put these numbers in perspective, let us compare the magnetic moment of these films with that measured in our Mn-doped ZnO films grown in the same vacuum chamber and measured in the same magnetometer. 8,21,22 In Mn-doped ZnO with concentration of Mn as high as 8% and similar carrier density, we measure a magnetic moment of only 0.35 l B /Mn at low temperatures.…”

The Chemical Form of Metal Species Released from Corroded Taper Junctions of Hip Implants: Synchrotron Analysis of Patient Tissue

“…The small pre-edge peaks, which represent transitions to d orbitals, in the spectra of anatase and rutile are very different to the pre-edge of Ti in the tissue. This higher pre-edge peak in spectra of type #Ti1 indicates much of the titanium may be a disordered oxide species 37 ; it bears a resemblance to the spectra of amorphous TiO 2 38 .…”

Effect of growth time on Ti-doped ZnO nanorods prepared by low-temperature chemical bath deposition

“…Several techniques have been proposed for the preparation of Ti-doped ZnO (TZN) thin films such as radio frequency (RF) sputtering [14] , pulsed laser deposition (PLD) [15] , chemical vapor deposition (CVD) [16] , and atomic layer deposition (ALD) [17] . These methods are costly and need high-temperature and/or high vacuum ambient, especially when compared to chemical bath deposition method (CBD).…”