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用时间分辨光谱研究了很大的Te组分范围内的ZnS1-xTex(x=00 05—085)合金的发光动力学特性,结果表明:不同形态的Te等电子中心具有不同的辐射复 合寿命,从几个ns到几十个ns的范围内变化,当x=015左右时,寿命达到最大值(约 40ns).其物理机理源于不同的Te等电子中心具有不同的局域化特性.当Te组分较小时,等 电子中心从Te1逐渐演变到Te2,Te3或Te4 时,相应发光寿命增加,表现出不断增强 的激子发光局域化特性;而当Te组分较大时,Te原子团变得较大,其局域势与基体原子势的 相互作用增强,等电子中心的局域化特性减弱,而基体价带扩展态特征变得明显起来,相应 发光寿命逐渐减小.还研究了激子束缚能随Te组分的变化以及发光强度随温度的变化关系, 所得结果进一步支持了时间分辨光谱研究所得到的结论.
关键词:
ZnS
等电子中心
时间分辨光谱
局域态 相似文献
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应用反胶束法制备了稀磁半导体Cd1-xMnxS量子点.量子点的大小可通过改变ωo值(wo=[水]/[表面活性剂])来控制.高分辨透射电镜的分析结果表明,量子点呈单分散性,是几乎没有缺陷的单晶体.量子点的大小约为4.8~6nm,随wo值增大而增大.电子能谱(EDS)测定结果表明,Mn2+离子在量子点中的摩尔分数为1.5%.由电子自旋共振(ESR)分析确定一部分Mn2+离子取代Cd2+离子位置而位于晶格,另一部分Mn2+离子位于Cd1-xMnxS的表面或间隙位置.吸收光谱显示,随着量子点变小,吸收带边发生蓝移,显示明显的量子尺寸效应.光致荧光光谱分析表明,发光峰属于Mn2+的4T1-6A1跃迁,而且随着ωo和粒径的增大,发光峰从2.26,2.10,2.05eV红移到1.88eV;其发光峰偏离2.12eV,主要是由于Mn2+离子位于扭曲的四面体晶体场所致. 相似文献
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世人瞩目的诺贝尔物理学奖在2014年授予蓝光发光二极管(LED)的三位发明者,他们的经历值得借鉴,也发人深省,带来许多有益的启示,引发我们更深入地理解基础与应用的关系和更恰当地评价物理研究的科学价值和社会价值. 相似文献
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文章从实验物理教学的范畴和性质出发,比较中外实验教学的差异,结合当前存在的问题,探讨理想的实验物理教学模式.提出实验物理教学应当以学生为中心,鼓励学生的自主创新精神和师生密切互动;发展实验教学中心应当以质量为重点,而不是盲目追求数量;努力把实验物理教学中心建设成为教学的平台、探索的基地、求知的乐园. 相似文献
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We employ photoluminescence (PL) and time-resolved PL to study exciton localization effect in InGaN epilayers.By measuring the exciton decay time as a function of the monitored emission energy at different temperatures,we have found unusual behaviour of the energy dependence in the PL decay process. At low temperature, the measured PL decay time increases with the emission energy. It decreases with the emission energy at 200K, and remains nearly constant at the intermediate temperature of 12OK. We have studied the dot size effect on the radiative recombination time by calculating the temperature dependence of the exciton recombination lifetime in quantum dots, and have found that the observed behaviour can be well correlated to the exciton localization in quantum dots. This suggestion is further supported by steady state PL results. 相似文献
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Optical Properties of Phase-Separated GaN1-xPx Alloys Grown by Light-Radiation Heating Metal-Organic Chemical Vapour Deposition 下载免费PDF全文
Based on the results of the temperature-dependent photoluminescence (PL) measurements, the broad PL emission in the phase-separated GaNP alloys with P compositions of 0.03, 0.07, and 0.15 has investigated. The broad PL peaks at 2.18, 2.12 and 1.83eV are assigned to be an emission from the optical transitions from several trap levels, possibly the iso-electronic trap levels related to nitrogen. With the increasing P composition (from 0.03 to 0.15), these iso-electronic trap levels are shown to become resonant with the conduction band of the alloy and thus optically inactive, leading to the apparent red shift (80-160meV) of the PL peak energy and the trend of the red shift is strengthened. No PL emission peak is observed from the GaN-rich GaNP region, suggesting that the photogenerated carriers in the GaN-rich GaNP region may recombine with each other via non-radiation transitions. 相似文献
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