Mid-infrared dielectric response of Fermi-degenerate electron-hole droplets in diamond
Mid-infrared dielectric response of Fermi-degenerate electron-hole droplets in diamond
复制标题
金刚石中费米简并电子空穴液滴的中红外介电响应
DOI：
10.1103/physrevb.106.235205
复制
发表时间：
2022
影响因子：
3.7
通讯作者：
Kuwata-Gonokami M.
中科院分区：
文献类型：
--
作者：
Omachi J.;Naka N.;Yoshioka K.;Kuwata-Gonokami M.
探索高度量子简并的电子空穴(e-h)态作为多体系统的性质是固体物理学中一个有趣的问题。电子空穴液滴(EHD)为研究极高密度的费米简并载流子状态提供了一个潜在的平台。在这里，我们提供了中红外(MIR)区载流子的介电响应测量，以明确地评估金刚石中EHD的e-h态的动态性质。在利用双光子吸收过程跨越禁带能量的光激发下，我们利用MIR探测光和深紫外区的时间分辨光致发光光谱进行了时间分辨差示透射谱的研究。通过将这两个时间分布联系起来，我们克服了以前的模糊发光分析的问题，阐明了MIR介电响应，揭示了EHD的表面等离子体共振(SPR)以及e-h库仑相互作用对动态介电响应的影响。因此，我们发现EHD内的载流子密度在2 ns内保持不变，而凝聚体积的衰减时间为1 ns，并且在此纳秒时间尺度内保持的交流电导弛豫率是IV类半导体中最高的。在出现SPR的高频区，我们预测了e-h散射率与探测频率的强烈依赖关系，这表明当在低频区探测时，动力学弛豫不会干扰超低温量子简并e-h系统中预期的有序形成。
Exploring the properties of a highly quantum-degenerate electron-hole (e-h) state as a many-body system is an interesting problem in solid-state physics. Electron-hole droplets (EHDs) offer a potential platform for investigating such a state of Fermi-degenerate carriers at an extremely high density. Herein we present dielectric response measurements of carriers in the mid-infrared (MIR) region for a definitive evaluation of the dynamic properties of the e-h state of EHDs in diamond. With photoexcitation across the band-gap energy by using the two-photon absorption process, we performed time-resolved differential transmission spectroscopy by using MIR probe light and time-resolved photoluminescence spectroscopy in the deep-ultraviolet region. By linking the two temporal profiles, we overcame the problem of previous ambiguous PL analyses and elucidated the MIR dielectric response that reveals the surface plasmon resonance (SPR) of EHDs and the effect of the e-h Coulomb interaction on the dynamic dielectric response. Thus, we found that the carrier density inside EHDs remained constant atup to 2 ns, whereas a decay time of 1 ns of the condensed volume was found and the AC conductivity relaxation rate ofmaintained during this nanosecond timescale was the highest among group-IV semiconductors. We predicted a strong dependence of the e-h scattering rate on the probe frequency in the high-frequency region in which SPR appeared, suggesting that—when probed in the low-frequency region—dynamical relaxation does not interfere with the order formation expected in quantum-degenerate e-h systems at ultralow temperatures.