Ultrafast Terahertz Nanoseismology of GaInN/GaN Multiple Quantum Wells
Ultrafast Terahertz Nanoseismology of GaInN/GaN Multiple Quantum Wells
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DOI：
10.1002/adom.202100258
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发表时间：
2021-05
影响因子：
9
通讯作者：
A. Mannan;F. Bagsican;Kota Yamahara;I. Kawayama;H. Murakami;H. Bremers;U. Rossow;A. Hangleiter;D. Turchinovich;M. Tonouchi
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文献类型：
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作者：
A. Mannan;F. Bagsican;Kota Yamahara;I. Kawayama;H. Murakami;H. Bremers;U. Rossow;A. Hangleiter;D. Turchinovich;M. Tonouchi
利用太赫兹(THz)发射光谱和显微技术研究了Ga0.8In0.2N/GaN多量子阱的电子和晶格动力学。THz辐射由三个不同的、不同时间的信号组成，其物理机制归因于：1)激光诱导多量子阱内建偏置电场的超快动态屏蔽；2)激发载流子的电容电荷振荡；3)GaN盖层与空气不连续处的相干声学声子(CAP)驱动的极化浪涌。这些多功能光学响应对量子阱宽度和光子能量有很强的依赖性。第一和第三太赫兹脉冲之间的时间间隔对应于CAP在MQW结构的GaN盖层上的传播，因此可以以10 nm的精度确定其厚度。
Terahertz (THz) emission spectroscopy and microscopy are applied to investigate the electron and lattice dynamics of Ga0.8In0.2N/GaN multiple quantum wells (MQWs). The THz emission consists of three distinct, differently timed signals, whose physical mechanisms are attributed to i) laser‐induced ultrafast dynamical screening of built‐in bias electric field in MQWs followed by ii) capacitive charge oscillation of the excited carriers and iii) the coherent acoustic phonon (CAP)‐driven polarization surge at the discontinuity between the GaN capping layer and air. These multifunctional optical responses show strong dependence on the quantum well width and photon energies. The temporal separation between the first and third THz pulses corresponds to the propagation of the CAP across the GaN capping layer of the MQW structure, whose thickness can thus be determined with 10 nm precision.