Luminescence spectroscopy of Cr <sup>3+</sup> ions in bulk single crystalline β-Ga <sub>2</sub> O <sub>3</sub>
A. Luchechko, V. Vasyltsiv, Yaroslav Zhydachevskyy, Markiyan Kushlyk, S. Ubizskii, A. Suchocki
Abstract
Abstract Detailed investigations of the spectroscopic properties of Cr 3+ ions in β-Ga 2 O 3 :0.05% Cr 3+ single crystals grown by the floating zone technique have been performed in the temperature range 4.5–550 K. The luminescence of Cr 3+ ions at low temperatures is due to narrow R-lines ( 2 E → 4 A 2 transitions) and their vibronic sidebands, whereas the broad intense band ( 4 T 2 → 4 A 2 transition) dominates at temperatures above 200 K. The vibronic sidebands of R-lines with amplitude of less than 5% of the R 1 -line at a temperature of 4.5 K cover the region of 700–735 nm. The temperature dependences of the luminescence intensity and the decay time of Cr 3+ ions indicate the same mechanism of quenching of R-line intensity and shortening of lifetime for 2 E of Cr 3+ ions. The temperature dependence of the R 1 -line decay time of β-Ga 2 O 3 :Cr 3+ with maximal temperature coefficient |Δτ/Δ T | = 0.023 ms K −1 at 120 K and maximal specific sensivitity |(Δτ/Δ T )τ −1 | = 0.017 K −1 at 160 K indicates an application potential of this phosphor for low-temperature fluorescence thermometry.