Paramagnetic dysprosium-doped zinc oxide thin films grown by pulsed-laser deposition

Abstract

Dysprosium(Dy)-doped zinc oxide (Dy:ZnO) thin films were fabricated on c-oriented sapphire substrate by pulsed-laser deposition with doping concentration ranging from 1 to 10 at. %. X-ray diffraction (XRD), Raman-scattering, optical transmission spectroscopy, and spectroscopic ellipsometry revealed incorporation of Dy into ZnO host matrix without secondary phase. Solubility limit of Dy in ZnO under our deposition condition was between 5 and 10 at. % according to XRD and Raman-scattering characteristics. Optical transmission spectroscopy and spectroscopic ellipsometry also showed increase in both transmittance in ultraviolet regime and band gap of Dy:ZnO with increasing Dy density. Zinc vacancies and zinc interstitials were identified by photoluminescence spectroscopy as the defects accompanied with Dy incorporation. Magnetic investigations with a superconducting quantum interference device showed paramagnetism without long-range order for all Dy:ZnO thin films, and a hint of antiferromagnetic alignment of Dy impurities was observed at highest doping concentration—indicating the overall contribution of zinc vacancies and zinc interstitials to magnetic interaction was either neutral or toward antiferromagnetic. From our investigations, Dy:ZnO thin films could be useful for spin alignment and magneto-optical applications.

Spectral-luminescent properties of vapor deposited Cr:ZnS thin films and their application as saturable absorbers for 15-μm erbium lasers

“…Figure 4 shows 1 st and 2 nd order Raman spectra of the bulk ZnS crystal and MBE-grown Cr:ZnS thin films with different concentrations on top of the sapphire substrate. The substrate spectrum shows Al 2 O 3 peaks at 379 cm −1 and 577 cm −1 [43], which are also present in all the thin film spectra. Bulk crystalline ZnS exhibits a number of maxima, particularly in the 200-350 cm −1 and 600-700 cm −1 ranges, typical for both cubic and wurtzite ZnS [44,45].…”

Optical and Magnetic Response of Pure and CU-Ions Substituted Dysprosium Oxide Thin Films for Various Applications

“…where ʽʽαʼʼ is the absorption coefficient, ʽʽhѵʼʼ is photon energy, ʽʽAʼʼ is proportionality constant, "E g " is optical band gap, "n" is an integer equal to 2 for an indirect and 1/2 for direct band gap in the above relation [34]. For the value of n=2 for Dy 2 O 3 and Cu/Dy 2 O 3 thin films, it states that an indirect band gap obtained for these structures.…”