Raman scattering studies of strain effects in (100) and (311)B GaAs1−xBix epitaxial layers
Raman scattering studies of strain effects in (100) and (311)B GaAs1−xBix epitaxial layers
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DOI：
10.1063/1.4831947
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发表时间：
2013-11
影响因子：
3.2
通讯作者：
J. Steele;R. Lewis;M. Henini;O. M. Lemine;A. Alkaoud
中科院分区：
文献类型：
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作者：
J. Steele;R. Lewis;M. Henini;O. M. Lemine;A. Alkaoud
我们报告了应变（100）和（311）B GaAs 1 −xBix外延层（x ≤ 0.039）的室温拉曼研究。拉曼光谱表现出双模行为，以及无序激活的类GaAs声子。实验结果表明，由于合金化，类GaAs LO（Γ）模发生了强烈的成分依赖性红移.峰值频率从具有合金化Bi分数x和引入的面内晶格应变e的纯GaAs的值（λ 293 cm−1）线性降低，ΔωLO=Δωalloy−Δωstrain。X射线衍射测量被用来确定x和ε，使得Δω合金被去耦，对于（100）GaAs 1 −xBix，估计为−12（±4）cm−1/x。在（311）B取向衬底上生长的样品的ΔωLO大约是（100）GaAs的两倍。通过研究Bi诱导的应变、合金化的影响以及在高折射率（311）B晶体生长期间形成的缺陷来解释这种红移的大差异。
We report room-temperature Raman studies of strained (100) and (311)B GaAs1−xBix epitaxial layers for x ≤ 0.039. The Raman spectra exhibit a two-mode behavior, as well as disorder-activated GaAs-like phonons. The experimental results show that the GaAs-like LO(Γ) mode experiences a strong composition-dependent redshift as a result of alloying. The peak frequency decreases linearly from the value for pure GaAs (∼293 cm−1) with the alloyed Bi fraction x and the introduced in-plane lattice strain e∥, by ΔωLO=Δωalloy−Δωstrain. X-ray diffraction measurements are used to determine x and e∥ allowing Δωalloy to be decoupled and is estimated to be −12(±4) cm−1/x for (100) GaAs1−xBix. ΔωLO is measured to be roughly double for samples grown on (311)B-oriented substrates to that of (100) GaAs. This large difference in redshift is accounted for by examining the Bi induced strain, effects from alloying, and defects formed during high-index (311)B crystal growth.