金纳米颗粒光散射提高InAs单量子点荧光提取效率  

Extraction efficiency enhancement of single InAs quantum dot emission through light scattering on the Au nanoparticles

作　　者：苏丹[1] 窦秀明[1] 丁琨[1] 王海艳[1] 倪海桥[1] 牛智川[1] 孙宝权[1] 

机构地区：[1]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

出　　处：《物理学报》2015年第23期198-203,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11204297)资助的课题~~

摘　　要：采用光学方法确定InAs/GaAs单量子点在样品外延面上的位置坐标,利用AlAs牺牲层把含有量子点的GaAs层剥离并放置在含有金纳米颗粒或平整金膜上,研究量子点周围环境不同对量子点自发辐射寿命及发光提取效率的影响.实验结果显示,剥离前后量子点发光寿命的变化小于13%,含有金纳米颗粒的量子点发光强度是剥离前的7倍,含有金属薄膜的量子点发光强度是剥离前的2倍.分析表明在金纳米颗粒膜上的量子点荧光强度的增加主要来自于金纳米颗粒对量子点荧光的散射效应,从而提高量子点发光的提取效率.Single semiconductor quantum dots（QDs） have been considered as the promising solid-state single photon sources.To obtain bright quantum sources,the key issue is to enhance extraction efficiency of the QD emission,which is challenging since QDs normally emit isotropically in a high refractive index material.In this article,we investigate the influence of Au nanoparticles on the QD photoluminescence（PL） extraction efficiency based on the techniques of optically positioned QDs and single QD emission detection.The In As QD samples studied are grown using the molecular beam epitaxy on a（001） GaAs substrate.The sample consists of,in sequence,a 200 nm GaAs buffer layer,a 100 nm Al As sacrificed layer,a 30 nm GaAs,a QD layer,and a 100 nm GaAs cap layer.The QD sample is mounted in a cryostat cooled down to 5 K,and excited by illumination of a 640 nm diode laser（CW or pulsed with a repetition frequency of 80 MHz）.Excitation laser beam is focused to an approximately 2 μm spot on the sample using a microscope objective（NA ： 0.5） which is mounted on a nanocube XY Z piezo nanopositioning stage with a scanning range of 100 × 100 × 100 μm3.The QD PL is collected using the same objective and measured using a 0.5 m focal length monochromator equipped with a silicon charge-coupled device（CCD）.The PL decay measurements are performed using a silicon avalanche photodiode（APD）and a time-correlated single-photon counting（TCSPC） board.In order to study the influence of different environments surrounding the QDs on the spontaneous emission rate and the extraction efficiency,the same QD emissions are measured under the conditions that：（1） A typical QD is at first chosen and optically positioned and then its emission is measured.（2） A GaAs layer containing the QDs is lifted off from the as-grown sample by an Al As sacrificed layer and placed on the Au film with or without Au nanoparticles.（3） Optical measurements are carried out to obtain the QD emission intensity.This technique enables us

关 键 词：金纳米颗粒 InAs单量子点 光散射 提取效率 

分 类 号：O471.1[理学—半导体物理]