Terahertz Emission Mechanisms in III–V Semiconductors: The Influence of Isoelectronic Dopants
Terahertz Emission Mechanisms in III–V Semiconductors: The Influence of Isoelectronic Dopants
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III-V 族半导体中的太赫兹发射机制：等电子掺杂剂的影响
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发表时间：
2020
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影响因子：
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通讯作者：
C. Vaisakh
中科院分区：
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作者：
R. Kini;C. Vaisakh
在过去的三十年里，人们对III-V半导体的超快光激发产生太赫兹辐射进行了广泛的研究。基于低温生长GaAs （LT-GaAs）的光导天线（PCAs）是广泛应用的太赫兹源/探测器之一。这些pca已经成为从光谱到成像等不同应用所需的可靠的桌面太赫兹辐射源。太赫兹辐射是由这些半导体通过瞬态光电流或非线性光学现象产生的。对于低带隙半导体，如InAs或GaSb，太赫兹辐射主要是由瞬态光电流引起的。瞬态光电流的产生是由于内置的表面场或由于强激光脉冲产生的电子和空穴迁移率的差异。掺铋等电子元素的III-V型半导体表现出巨大的带隙弯曲（例如，GaAsBi中Bi的80 - 90mev /%）、空穴浓度增加和巨大的自旋轨道弯曲等有趣的特性。在本章中，我们讨论了Bi掺入对两种典型III-V型半导体（即GaAs和GaSb）中太赫兹发射的影响以及导致太赫兹现象的机制。尽管这两种合金的太赫兹发射机制不同，但有报道称，随着铋浓度的增加，两种合金的太赫兹发射效率都有所提高。讨论了这些III-V: Bi合金的潜在应用。
The generation of terahertz (THz) radiation by ultrafast optical excitation of III–V semiconductors has been studied extensively in the last three decades. One of the widely used THz sources/detectors is photoconductive antennas (PCAs) based on low-temperature grown GaAs (LT-GaAs). These PCAs have acted as reliable table-top sources of THz radiation required for different applications ranging from spectroscopy to imaging. THz radiation is generated from these semiconductors by transient photocurrents or by the nonlinear optical phenomenon. In the case of low-bandgap semiconductors, like InAs or GaSb, THz emission is mainly due to transient photocurrents. The transient photocurrent arises due to the built-in surface field or due to the difference in the mobility of electrons and holes generated by the intense laser pulse. III–V semiconductors doped with isoelectronic elements like bismuth have shown interesting properties like giant bandgap bowing, (e.g., 80–90 meV/% of Bi in GaAsBi), increase in hole concentration, and giant spin-orbit bowing. In this chapter, we discuss the effect of Bi incorporation on the THz emission and the mechanisms responsible for THz phenomena in two typical III–V semiconductors, viz. GaAs and GaSb. Even though the THz emission mechanism in these two alloys is different, an enhancement in the THz emission efficiency in both the alloys with increased Bi concentration has been reported. We discuss potential applications of these III–V: Bi alloys.