Metalorganic chemical vapor phase epitaxy of narrow-band distributed Bragg reflectors realized by GaN:Ge modulation doping
Metalorganic chemical vapor phase epitaxy of narrow-band distributed Bragg reflectors realized by GaN:Ge modulation doping
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DOI：
10.1016/j.jcrysgro.2016.01.027
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发表时间：
2016-04-15
影响因子：
1.8
通讯作者：
Strittmatter, Andre
中科院分区：
文献类型：
--
作者：
Berger, Christoph;Lesnik, Andreas;Strittmatter, Andre
本文报道了仅采用氮化镓掺杂浓度周期性调制的分布式布拉格反射器（DBR）的金属有机气相外延（MOVPE）。掺杂调制通过burstein - moss效应改变GaN的折射率。高掺杂GaN:Ge的MOVPE生长和掺杂浓度调制至少两个数量级在几纳米内是实现2-3%的折射率对比度所必需的。尽管存在锗记忆效应和合并延迟，这种调制特性仍然可以实现。我们通过将标称掺杂浓度为1.6 x 10(20) cm（-3）的GaN:Ge作为低折射率材料，将无意掺杂的GaN作为高折射率层，实现了多达100层对的DBRs。扫描透射电镜图像显示DBR结构在横向和纵向上具有突兀的界面和均匀的层厚。设计用于蓝色和近紫外光谱区域的dbr的反射率测量显示出窄阻带，在418 nm处最大反射率为85%，在370 nm处甚至达到95%。在这种dbr上生长的InGaN/GaN多量子阱结构具有较窄的发射光谱，线宽小于3 nm，发射强度显著增加。(C) 2016 Elsevier B.V.版权所有
We report on metalorganic vapor phase epitaxy (MOVPE) of distributed Bragg reflectors (DBR) applying a periodic modulation of the GaN doping concentration only. The doping modulation changes the refractive index of GaN via the Burstein-Moss-effect. MOVPE growth of highly doped GaN:Ge and modulation of the dopant concentration by at least two orders of magnitude within few nanometers is required to achieve a refractive index contrast of 2-3%. Such modulation characteristic is achieved despite the presence of Ge memory effects and incorporation delay. We realized DBRs with up to 100 layer pairs by combining GaN:Ge with a nominal doping concentration of 1.6 x 10(20) cm(-3) as low refractive index material with unintentionally doped GaN as high-refractive index layer. Scanning transmission electron microscope images reveal DBR structures with abrupt interfaces and homogenous layer thicknesses in lateral and vertical direction. Reflectance measurements of DBRs designed for the blue and near UV-spectral region show a narrow stopband with a maximum reflectivity of 85% at 418 nm and even 95% at 370 nm. InGaN/GaN multi-quantum well structures grown on top of such DBRs exhibit narrow emission spectra with linewidths below 3 nm and significantly increased emission intensity. (C) 2016 Elsevier B.V. All rights reserved.