Two-Mode Behavior in Raman Spectra of Al0.86Ga0.14N Alloy under High Pressure
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摘要: 氮化铝镓(AlxGa1-xN)合金是重要的半导体材料,在发光二极管和紫外探测器等领域都有广阔的应用前景。对高铝成分AlxGa1-xN合金的高压行为研究还较为稀少。利用原位拉曼光谱对高铝成分的AlxGa1-xN合金与本征的GaN和AlN进行了对比研究。结果表明,Al原子掺杂引起GaN亚晶格的收缩效应与对本征GaN施加外部正压力的作用效果等效,引起AlN亚晶格的拉伸效应与对本征AlN施加外部负压力的作用效果相似。Al原子掺杂引起Al0.86Ga0.14N晶格的收缩效应在晶胞c轴方向上更显著。研究还发现,Al原子掺杂对类AlN拉曼声子振动模高压行为的影响比类GaN更明显。Abstract: Ternary AlxGa1-xN alloy is an important semiconductor for devices in the ultraviolet and visible parts of the spectrum.So far, most studies of high Al content AlxGa1-xN alloy were mainly focused on their properties under ambient pressure and at room temperature but few on their high-pressure behavior.In this work, high Al content Al0.86Ga0.14N was investigated using the in-situ Raman scattering spectrum, and the intrinsic AlN and GaN were also studied as a comparison.The results show that the substitution of Ga by Al can be regarded as a kind of chemical pressure, and the pressure effect caused by the internal substitution can reach that caused by the external compression for GaN and the internal extension for AlN.Due to the crystalline anisotropy, the pressure effect caused by the internal substitution is more significant along the c-axis than that perpendicular to the c-axis.Moreover, the negative pressure, caused by the internal substitution, has a more significant influence on the high-pressure behavior of the AlN-like mode than that of the GaN-like mode.
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Key words:
- AlxGa1-xN /
- semiconductor alloy /
- high pressure /
- Raman scattering /
- "two-mode" behavior /
- negative pressure
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图 1 (a)、(b)、(c) AlN、GaN和Al0.86Ga0.14N的室温常压拉曼光谱的分峰拟合谱, (d) GaN (AlN)的不同拉曼声子模的原子振动方式示意图
Figure 1. (a), (b), (c) The fitted Raman spectrum of the Lorentzian for AlN, GaN and Al0.86Ga0.14N under ambient pressure and at room temperature; (d) the atomic displacement of different Raman modes for hexagonal GaN (AlN)
表 1 利用方程(2)拟合所得的零压拉曼声子频率ω0和压力系数(dω/dp)p=0
Table 1. Zero-pressure Raman phonon frequencies ω0 and pressure coefficients (dω/dp)p=0 as fitted from the parameters used in Eq.(2)
Sample ω0/(cm-1) (dω/dp)p=0/(cm-1·GPa-1) Ref. A1(TO) E1(TO) E2(high) A1(TO) E1(TO) E2(high) GaN 533.8 560.0 568.7 3.79 3.56 3.83 This work 531.7 558.2 567.0 3.90 3.94 4.24 [20] 532.2 560.6 569.1 4.20 3.80 4.16 [21] 531.0 560.0 568.0 4.06 3.68 4.17 [22] Al0.86Ga0.14N GaN-like 585.0 597.2 608.4 3.95 4.08 4.10 This work Al0.86Ga0.14N AlN-like 618.4 660.0 650.0 4.02 4.89 5.27 This work AlN 610.4 668.9 654.0 3.87 4.12 4.82 This work 608.5 669.3 655.5 4.40 4.55 4.99 [20] 608.0 666.0 653.0 4.35 5.33 5.40 [23] 611.0 671.6 659.3 3.50 4.84 4.97 [24] 610.0 669.0 657.0 4.05 4.52 4.78 [25] -
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