Luminescence of Eu3+ in GaN(Mg, Eu): Transitions from the 5D1 level
Luminescence of Eu3+ in GaN(Mg, Eu): Transitions from the 5D1 level
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DOI：
10.1063/1.5001143
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发表时间：
2017-12-11
影响因子：
4
通讯作者：
Prakash, R.
中科院分区：
文献类型：
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作者：
Singh, A. K.;O'Donnell, K. P.;Prakash, R.
Eu 掺杂的 GaN(Mg) 示例了具有相同光致发光缺陷的两种构型 Eu0 和 Eu1(Mg) 之间的迟滞光致变色切换。使用上述带隙激发，我们研究了该缺陷的两种构型从激发的 Eu3+ D-5(1) 能级跃迁的光致发光 (TDPL) 的温度依赖性。在样品冷却过程中，Eu0 的 D-5(1)-> F-7 (0,1,2) 转变在低于 200 K 的温度下显现出来，而 Eu1(Mg) 的转变仅在转换过程中出现。观察到的线位置验证了 F-7(0,1,2) 能级的晶体场能量。 Eu0 的 D-5(1)-> F-7(1) 和 D-5(0)-> F-7(J) 跃迁的 TDPL 剖面显示，从 D-5(1) 能级开始可观察到的发射与先前观察到的、但迄今为止无法解释的、在冷却至 200 K 以下时其 D-5(0)-> F-7(J) 发射强度的降低一致。因此，D-5(0)-> F-7(J) TDPL 异常表明由于较低温度下 D-5(1) 和 D-5(0) 水平之间的声子辅助弛豫减少而导致 D-5(1) 数量的备份。我们根据 Eu0 的温度依赖性瞬态发光测量讨论了这一令人惊讶的结果。 (c) 2017 年作者。
Eu-doped GaN(Mg) exemplifies hysteretic photochromic switching between two configurations, Eu0 and Eu1(Mg), of the same photoluminescent defect. Using the above-bandgap excitation, we studied the temperature dependence of photoluminescence (TDPL) of transitions from the excited D-5(1) level of Eu3+ for both configurations of this defect. During sample cooling, D-5(1)-> F-7 (0,1,2) transitions of Eu0 manifest themselves at temperatures below similar to 200 K, while those of Eu1(Mg) appear only during switching. The observed line positions verify crystal field energies of the F-7(0,1,2) levels. TDPL profiles of D-5(1)-> F-7(1) and D-5(0)-> F-7(J) transitions of Eu0 show an onset of observable emission from the D-5(1) level coincident with the previously observed, but hitherto unexplained, decrease in the intensity of its D-5(0)-> F-7(J) emission on cooling below 200 K. Hence, the D-5(0)-> F-7(J) TDPL anomaly signals a back-up of D-5(1) population due to a reduction in phonon-assisted relaxation between D-5(1) and D-5(0) levels at lower temperatures. We discuss this surprising result in the light of temperature-dependent transient luminescence measurements of Eu0. (c) 2017 Author(s).