Raman scattering study of photoexcited plasma in GaAsBi/GaAs heterostructures: Influence of carrier confinement on photoluminescence
Raman scattering study of photoexcited plasma in GaAsBi/GaAs heterostructures: Influence of carrier confinement on photoluminescence
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DOI：
10.1016/j.mssp.2023.107543
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发表时间：
2023
影响因子：
4.1
通讯作者：
Sho Hasegawa;N. Hasuike;K. Kanegae;H. Nishinaka;M. Yoshimoto
中科院分区：
文献类型：
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作者：
Sho Hasegawa;N. Hasuike;K. Kanegae;H. Nishinaka;M. Yoshimoto
GaAsBi合金是近红外光电应用的潜在候选者，如发光二极管、激光二极管、雪崩光电二极管和太阳能电池。本文利用拉曼光谱研究了分子束外延生长的GaAs1-xBix/GaAs（1.7≤x≤8.6%）异质结构中的光激发等离子体。在室温下，用连续波激光激发产生了强声子-等离子体耦合模式（LOPC）。Bi含量在x = 3.9 ~ 8.6%范围内明显可见LOPC模式的上分支（L+模式），说明具有较好载流子迁移率的光激发载流子被限制在GaAsBi/GaAs异质结构中。基于介电模型的拉曼光谱线形分析得到的光激发载流子密度随着Bi含量从1.7增加到6.4%而增加。这表明由于GaAsBi/GaAs异质界面处较大的导带偏移，GaAsBi层的载流子溢出被抑制。此外，利用光激发L+模式的阻尼常数计算的光迁移率随着Bi含量的增加而逐渐降低。这可能是由于缺陷密度随着生长温度的降低而增加。我们的研究结果为基于GaAsBi合金的高性能光电器件的发展提供了有价值的见解，并显示了拉曼光谱在异质结构中评估载流子约束的潜力。
GaAsBi alloys are potential candidates for near-infrared optoelectronic applications, such as light-emitting diodes, laser diodes, avalanche photodiodes, and solar cells. In this paper, photoexcited plasma in GaAs1-xBix/GaAs (1.7 ≤ x ≤ 8.6%) heterostructures grown by molecular beam epitaxy was investigated using Raman spectroscopy. The strong LO phonon-plasmon coupled mode (LOPC) was generated by continuous-wave laser excitation at room temperature. The upper branch of the LOPC mode (L+mode) was clearly observed for Bi contents from x = 3.9–8.6%, which indicates that photoexcited carriers with relatively good carrier mobility were confined in the GaAsBi/GaAs heterostructure. The photoexcited carrier density that was obtained by line shape analysis of the Raman spectra based on a dielectric model increased as the Bi content increased from 1.7 to 6.4%. This indicates that carrier overflow from the GaAsBi layer was suppressed because of the larger conduction band offset at the GaAsBi/GaAs heterointerface. In addition, the optical mobility calculated using the damping constant of the photoexcited L+mode gradually decreased with increasing Bi content. This may be attributed to an increased defect density with decreasing growth temperature. Our findings provide valuable insight into the development of high-performance optoelectronic devices based on GaAsBi alloys and show the potential of Raman spectroscopy for evaluation of carrier confinement in heterostructures.