Charge state of vacancy defects in Eu-doped GaN
Charge state of vacancy defects in Eu-doped GaN
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Eu掺杂GaN中空位缺陷的电荷态
DOI：
10.1103/physrevb.96.064308
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发表时间：
2017
影响因子：
3.7
通讯作者：
and V. Dierolf
中科院分区：
文献类型：
--
作者：
B. Mitchell;N. Hernandez;D. Lee;A. Koizumi;Y. Fujiwara;and V. Dierolf
Eu 离子被掺杂到 GaN 中，以在电流注入下实现红光发光，其中 Eu 离子与空位等本征缺陷之间的耦合发挥着重要作用。然而，空位的电荷状态及其对Eu离子的光学和磁性的影响尚未被探索。通过结合第一性原理计算和实验结果，研究了Eu离子周围缺陷环境电荷态的影响。我们已经确定了两个通过局部空位缺陷的电荷态相关的 EU 中心。人们发现这两个中心表现出相互的亚稳定性，使得每个中心都可以在一种配置中被激发并以另一种配置发射。人们发现这种亚稳定性取决于温度和激发激光的波长。此外，发现这些中心之一的有效磁因子远大于预期的隔离值，这可以通过 Eu 周围缺陷环境的电荷态变化来解释。这一预测还可以为先前在 GaN : Eu 和其他 GaN:RE 系统中观察到的饱和磁化强度提供新的解释。
Eu ions have been doped into GaN in order to achieve red luminescence under current injection, where coupling between the Eu ions and intrinsic defects such as vacancies are known to play an important role. However, the charge state of the vacancies and the impact it would have on the optical and magnetic properties of the Eu ions have not been explored. Through a combination of first-principle calculations and experimental results, the influence of the charge state of the defect environment surrounding the Eu ions has been investigated. We have identified two Eu centers that are related through the charge state of a local vacancy defect. These two centers were found to exhibit a mutual metastability, such that each center can be excited in one configuration and emit as the other. This metastability was found to be dependent on temperature and the wavelength of the excitation laser. Furthermore, one of these centers was found to have an effective magneticfactor that is substantially larger than what is expected for an isolatedion and is explained by a change in the charge state of the defect environment around the Eu. This prediction could also offer a new explanation for the saturation magnetization previously observed in GaN : Eu and other GaN:RE systems.