Siqi Li, Xiao Liang, Pengfei Shao, Songlin Chen, Zhenhua Li, Xujun Su, Tao Tao, Zili Xie, M. Ajmal Khan, Li Wang, T. T. Lin, Hideki Hirayama, Bin Liu, Dunjun Chen, Ke Wang, Rong Zhang
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引用次数: 0
摘要
目前,基于氮化铝的深紫外发光器件的效率仍然很低。这些困难主要源于氮化铝的基本材料特性。这项研究采用了单层尺度的 (AlN)m/(GaN)n 有序数字合金 (DA) 作为氮化铝随机合金的替代品,m 和 n 是单层的数量。X 射线衍射扫描显示了清晰的卫星峰,验证了通过分子束外延(MBE)生长的 AlN/GaN DAs 具有良好的周期性,透射电子显微镜结果显示了原子级的锐利光滑界面和相当精确的 m:n 值,与设计完全吻合。具有高当量铝成分的硅掺杂 (AlN)m/(GaN)n DA 的电子密度明显高于在相同分子束外延系统中生长的传统 AlGaN:Si 无规合金。DAs中的硅掺杂电离能仅为2-5 meV,远低于常规无规合金。具有较薄 AlN 隔层的 DA 的光发射发生了红移,这表明 GaN 井之间存在较强的耦合,从而在垂直方向上形成了迷你带。研究结果表明,(AlN)m/(GaN)n DAs 具有作为电子功能替代品应用于各种器件的潜力。
Monolayer-scale AlN/GaN digital alloys grown by plasma-assisted molecular beam epitaxy
The efficiency of usual AlGaN based deep ultraviolet light-emitting devices is still quite low. The difficulties are basically originated from the fundamental material properties of AlGaN. This work has adopted monolayer-scale (AlN)m/(GaN)n ordered digital alloys (DAs) as alternatives to AlGaN random alloys, m and n are the numbers of monolayers. X-ray diffraction scans have demonstrated clear satellite peaks, verifying good periodicity of AlN/GaN DAs grown by molecular beam epitaxy (MBE), and transmission electron microscopy results have revealed atomically sharp and smooth interfaces and quite precise m:n values agreeing well with designs. The electron densities of Si-doped (AlN)m/(GaN)n DAs with high equivalent Al compositions are significantly higher than those of conventional AlGaN:Si random alloys grown in the same MBE system. Si dopant ionization energies in DAs are only 2–5 meV, much lower than that for usual random alloys. The red shift of the light emission for DAs with thinner AlN barriers has suggested strong coupling between the GaN wells and thus formation of a miniband in a vertical direction. The results have demonstrated the potential of the (AlN)m/(GaN)n DAs as electronically functional alternatives for various device applications.
期刊介绍:
Applied Physics Letters (APL) features concise, up-to-date reports on significant new findings in applied physics. Emphasizing rapid dissemination of key data and new physical insights, APL offers prompt publication of new experimental and theoretical papers reporting applications of physics phenomena to all branches of science, engineering, and modern technology.
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