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arXiv 1610.06342cond-mat.mes-hallcond-mat.mtrl-sci
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量子限制laser结构中激子和激子Mott跃迁的负激活能和介电特性

Negative activation energy and dielectric signatures of excitons and excitonic Mott transitions in quantum confined laser structures

Amit Bhunia, Kanika Bansal, Mohamed Henini, Marzook S. Alshammari, Shouvik Datta

摘要:

大多数情况下,光学光谱被用来研究激子的物理,而它们的电学证据几乎没有探索。在这里,我们研究了一个正向偏压激活的差分电容响应的GaInP-AlGaInP基多量子阱激光二极管跟踪激子的存在,使用电气测量。发光后负激活能的出现被理解为在中等范围的载流子注入下稳态激子布居的化学特征。在用分子束外延生长的InGaAs-GaAs量子点激光器结构中也观察到类似的确证结果。随着偏置的增加,测得的差分电容响应慢慢消失。这表示在GaInP-AlGaInP激光二极管中激子相到电子-空穴等离子体的逐渐Mott跃迁。随着正向偏压的增加,电致发光光谱中越来越多的高能量尾部的指数形状进一步证实了这一点,这源于自由电子和空穴的非简并种群的增长。激子的电学和光学性质之间的这种实验相关性可以用于推进下一代激子器件。

英文摘要:

Mostly, optical spectroscopies are used to investigate the physics of excitons, whereas their electrical evidences are hardly explored. Here, we examined a forward bias activated differential capacitance response of GaInP-AlGaInP based multi-quantum well laser diodes to trace the presence of excitons using electrical measurements. Occurrence of negative activation energy after light emission is understood as thermodynamical signature of steady state excitonic population under intermediate range of carrier injections. Similar corroborative results are also observed in an InGaAs-GaAs quantum dot laser structure grown by molecular beam epitaxy. With increasing biases, the measured differential capacitance response slowly vanishes. This represents gradual Mott transition of an excitonic phase into an electron-hole plasma in a GaInP-AlGaInP laser diode. This is further substantiated by more and more exponentially looking shapes of high energy tails in electroluminescence spectra with increasing forward bias, which originates from a growing non-degenerate population of free electrons and holes. Such an experimental correlation between electrical and optical properties of excitons can be used to advance the next generation excitonic devices.

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