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InAs/GaAs量子点1.3 μm单光子发射特性
引用本文:张志伟,赵翠兰,孙宝权. InAs/GaAs量子点1.3 μm单光子发射特性[J]. 物理学报, 2018, 67(23): 237802-237802. DOI: 10.7498/aps.67.20181592
作者姓名:张志伟  赵翠兰  孙宝权
作者单位:1. 内蒙古民族大学物理与电子信息学院, 通辽 028043;2. 中国科学院半导体研究所, 半导体超晶格国家重点实验室, 北京 100083
基金项目:国家自然科学基金(批准号:11464034)和内蒙古自治区自然科学基金(批准号:2016MS0119)资助的课题.
摘    要:采用双层耦合量子点的分子束外延生长技术生长了InAs/GaAs量子点样品,把量子点的发光波长成功地拓展到1.3 μm.采用光刻的工艺制备了直径为3 μm的柱状微腔,提高了量子点荧光的提取效率.在低温5 K下,测量得到量子点激子的荧光寿命约为1 ns;单量子点荧光二阶关联函数为0.015,显示单量子点荧光具有非常好的单光子特性;利用迈克耳孙干涉装置测量得到单光子的相干时间为22 ps,对应的谱线半高全宽度为30 μeV,且荧光谱线的线型为非均匀展宽的高斯线型.

关 键 词:InAs/GaAs量子点  1.3 μm  单光子发射
收稿时间:2018-08-24

1.3 μm single photon emission from InAs/GaAs quantum dots
Zhang Zhi-Wei,Zhao Cui-Lan,Sun Bao-Quan. 1.3 μm single photon emission from InAs/GaAs quantum dots[J]. Acta Physica Sinica, 2018, 67(23): 237802-237802. DOI: 10.7498/aps.67.20181592
Authors:Zhang Zhi-Wei  Zhao Cui-Lan  Sun Bao-Quan
Affiliation:1. College of Physics and Electronic Information, Inner Mongolia University for Nationalities, Tongliao 028043, China;2. State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Abstract:Single-photon emitters are crucial for the applications in quantum communication, random number generation and quantum information processing. Self-assembled InAs/GaAs quantum dots (QDs) have demonstrated to have singlephoton emission with high extraction efficiency, single-photon purity, and photon indistinguishability. Thus they are considered as the promising deterministic single-photon emitters. To extend the emission wavelength of InAs/GaAs QDs to telecom band, several methods have been developed, such as the strain engineered metamorphic quantum dots, the use of strain reducing layers and the strain-coupled bilayer of QDs. In fact, it is reported on single-photon emissions based on InAs/InP QDs with an emission wavelength of 1.55μm, but it is difficult to combine such QDs with a high-quality distributed Bragg reflector (DBR) cavity because the refractive index difference between InP and InGaAsP is too small to obtain a DBR cavity with high quality factor. Here we investigate 1.3μm single-photon emissions based on selfassembled strain-coupled bilayer of InAs QDs embedded in micropillar cavities. The studied InAs/GaAs self-assembled QDs are grown by molecular beam epitaxy on a semi-insulating (100) GaAs substrate through strain-coupled bilayer of InAs QDs, where the active QDs are formed on the seed QDs capped with an InGaAs layer, and two-layer QDs are vertically coupled with each other. In such a structure the emission wavelength of QDs can be extended to 1.3μm. The QDs with a low density of about 6×108 cm-2 are embedded inside a planar 1-λ GaAs microcavity sandwiched between 20 and 8 pairs of Al0.9Ga0.1As/GaAs as the bottom and top mirror of a DBR planar cavity, respectively. Then the QD samples are etched into 3μm diameter micropillar by photolithography and dry etching. The measured quality factor of studied pillar cavity has a typical value of approximately 300. Photoluminescence (PL) spectra of QDs at a temperature of 5 K are examined by using a micro-photoluminescence setup equipped with a 300 mm monochromator and an InGaAs linear photodiode array detector. A diode laser with a continuous wave or a pulsed excitation repetition rate of 80 MHz and an excitation wavelength of 640 nm is used to excite QDs through an near-infrared objective (NA 0.5), and the PL emission is collected by the same objective. The time-resolved PL of the QDs is obtained by a time-correlated single photon counting. The second-order correlation function is checked by a Hanbury-Brown and Twiss setup through using ID 230 infrared single-photon detectors.In summary, we find that the 1.3μm QD exciton lifetime at 5 K is measured to be approximately 1 ns, which has the same value as the 920 nm QD exciton lifetime. The second-order correlation function is measured to be 0.015, showing a good characteristic of 1.3μm single photon emission. To measure the coherence time, i.e., to perform highresolution linewidth measurements, of the QDs emitted at the wavelength of 920 and 1300 nm, we insert a Michelson interferometer in front of the spectrometer. The obtained coherence time for 1.3μm QDs is 22 ps, corresponding to a linewidth of approximately 30μeV. Whereas, the coherence time is 216 ps for 920 nm QDs, corresponding to a linewidth of approximately 3μeV. Furthermore, both emission spectral lineshapes are different. The former is of Gaussian-like type, while the latter is of Lorentzian type.
Keywords:InAs/GaAs quantum dots  1.3 μm  single photon emission
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