Hysteretic photochromic switching of Eu-Mg defects in GaN links the shallow transient and deep ground states of the Mg acceptor.
Hysteretic photochromic switching of Eu-Mg defects in GaN links the shallow transient and deep ground states of the Mg acceptor.
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DOI：
10.1038/srep41982
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发表时间：
2017-02-03
影响因子：
4.6
通讯作者：
Boćkowski M
中科院分区：
文献类型：
--
作者：
Singh AK;O'Donnell KP;Edwards PR;Lorenz K;Kappers MJ;Boćkowski M
虽然Mg对GaN的p型激活是一种成熟的商业技术，但GaN中Mg受体的性质仍然存在争议。在这里，我们使用注入的Eu作为“旁观者离子”，探测双掺杂GaN（Mg）：Eu中Mg的晶格位置。这种材料的光致发光光谱的两种配置，Eu 0和Eu 1（镁），相同的Eu-Mg缺陷，具有双曲线的时间依赖于“开关”从Eu 0到Eu 1（镁）之间的滞后光致变色开关（HPS）。样品温度和355 nm处的入射光强度在几个数量级上调节特征切换时间，从12.5 K、~100 mW/cm 2下的不到一秒到50 K、1 mW/cm 2下的（估计）几个小时。在Lany-Zunger模型中，将Eu-Mg缺陷组态与Mg受主的浅瞬态和深基态联系起来，确定了它们之间的能垒为27.7（4）meV，与理论预测相符合。实验结果进一步表明，在低温下，深基态的空穴定位在轴向键合到Mg受体的N原子上。
Although p-type activation of GaN by Mg underpins a mature commercial technology, the nature of the Mg acceptor in GaN is still controversial. Here, we use implanted Eu as a ‘spectator ion’ to probe the lattice location of Mg in doubly doped GaN(Mg):Eu. Photoluminescence spectroscopy of this material exemplifies hysteretic photochromic switching (HPS) between two configurations, Eu0 and Eu1(Mg), of the same Eu-Mg defect, with a hyperbolic time dependence on ‘switchdown’ from Eu0 to Eu1(Mg). The sample temperature and the incident light intensity at 355 nm tune the characteristic switching time over several orders of magnitude, from less than a second at 12.5 K, ~100 mW/cm2 to (an estimated) several hours at 50 K, 1 mW/cm2. Linking the distinct Eu-Mg defect configurations with the shallow transient and deep ground states of the Mg acceptor in the Lany-Zunger model, we determine the energy barrier between the states to be 27.7(4) meV, in good agreement with the predictions of theory. The experimental results further suggest that at low temperatures holes in deep ground states are localized on N atoms axially bonded to Mg acceptors.