Influence of chromium concentration on the optical–electronic properties of ruby microstructures

Abstract

Films of amorphous aluminium nitride (AlN) were prepared by conventional radio frequency sputtering of an Al + Cr target in a plasma of pure nitrogen. The Cr-to-Al relative area determines the Cr content, which remained in the ∼0–3.5 at% concentration range in this study. Film deposition was followed by thermal annealing of the samples up to 1050 °C in an atmosphere of oxygen and by spectroscopic characterization through energy dispersive x-ray spectrometry, photoluminescence and optical transmission measurements. According to the experimental results, the optical–electronic properties of the Cr-containing AlN films are highly influenced by both the Cr concentration and the temperature of the thermal treatments. In fact, thermal annealing at 1050 °C induces the development of structures that, because of their typical size and distinctive spectral characteristics, were designated by ruby microstructures (RbMSs). These RbMSs are surrounded by a N-rich environment in which Cr3+ ions exhibit luminescent features not present in other Cr3+-containing systems such as ruby, emerald or alexandrite. The light emissions shown by the RbMSs and surroundings were investigated according to the Cr concentration and temperature of measurement, allowing the identification of several Cr3+-related luminescent lines. The main characteristics of these luminescent lines and corresponding excitation–recombination processes are presented and discussed in view of a detailed spectroscopic analysis.

Magnetic and optical properties of virgin arc furnace grown MgO crystals

“…The same was observed by Cossolino and Zanatta in ruby microstructure doped with Cr [14]. Similar behavior exhibits second narrow band peaking at 721 nm (red shift of about 5 nm), which we associated with vibronic sidebands of the N line [15].…”

Photoluminescence Comparison of Different Substrates on AlN: Cr Thin Films for Optoelectronic Devices

“…Various methods could be used for doped thin-film synthesis, such as RF sputtering, DC sputtering, magnetron sputtering, chemical vapor deposition, metal oxide chemical vapor deposition, molecular beam epitaxy, and ion implantation [6,7], but the most suitable method is the one where the target contamination is avoided and a conformal thin film could be obtained with cost-effective methods. The aforementioned techniques were already been reported by researchers for transition metal doping [8,9] where they studied the electronic and magnetic properties of transition metal-doped thin films instead of their structural and optical properties [10,11] which readily change by dopant material and the doping techniques. Moreover, the substrate effect of transition metal-doped prepared thin film was not observed previously.…”