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1.3μm.采用光刻的工艺制备了直径为3μm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30μeV,且荧光谱线的线型为非均匀展宽的高斯线型.
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 1.55 μm, 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 1.3 μm 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 1.3 μm. 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 3 μm 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
作者
张志伟
赵翠兰
孙宝权
Zhang Zhi-Wei;Zhao Cui-Lan;Sun Bao-Quan(College of Physics and Electronic Information,Inner Mongolia University for Nationalities,Tongliao 028043,China;State Key Laboratory for Superlattices and Microstructures,Institute of Semiconductors,Chinese Academy of Sciences,Beijing 100083,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2018年第23期219-225,共7页
Acta Physica Sinica
基金
国家自然科学基金(批准号:11464034)
内蒙古自治区自然科学基金(批准号:2016MS0119)资助的课题.
