Growth and properties of semiconductor core/shell nanocrystals with InAs cores
Growth and properties of semiconductor core/shell nanocrystals with InAs cores
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DOI：
10.1021/ja001386g
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发表时间：
2000-10-11
影响因子：
15
通讯作者：
Banin, U
中科院分区：
文献类型：
--
作者：
Cao, YW;Banin, U
采用两步合成法，在不同半径的InAs核上生长了m-V族半导体壳层（InP和GaAs）和II-VI族半导体壳层（CdSe、ZnSe和ZnS）的核/壳半导体纳米晶。在第一步中制备核，并且在第二步中使用有机金属前体在配位溶剂中的高温热解来生长壳。通过吸收和光致发光光谱监测核/壳生长。InP或CdSe壳的生长时的带隙移动到红色，而对于ZnSe和ZnS壳具有较大的带偏移相对于InAs，带隙能量被保持。这种行为是通过使用球盒模型内的粒子的带隙能量计算再现的。InAs/InP核/壳的光致发光量子产率被淬灭，但InAs/CdSe和InAs/ZnSe核/壳的光致发光量子产率大幅增加至20%。对于InAs/ZnS核/壳的光致发光量子产率的增强较小，高达8%。核/壳纳米晶体，其特征在于使用透射电子显微镜，X射线光电子能谱，和粉末X射线衍射。X射线光电子能谱提供了壳生长的证据。X射线衍射峰位移和窄壳生长，提供了外延生长模式的证据。X射线衍射图案的模拟再现了这两种效果，并且显示在核和核/壳纳米晶体中的非常四到五层中存在一个堆垛层错。与核相比，InAs/CdSe和InAs/ZnSe核/壳的抗氧化稳定性显著提高，并且与典型的近TR激光染料IR 140相比，光稳定性显著更好。核/壳纳米晶体与InAs核心建议：作为一种新型的荧光团覆盖近红外光谱范围，与传统的近TR激光染料相比，具有高的发射量子产率和改善的稳定性。
Core/shell semiconductor nanocrystals with InAs cores were synthesized and characterized m-V semiconductor shells (InP and GaAs), and II-VI semiconductor shells (CdSe, ZnSe, and ZnS) were overgrown on InAs cores with various radii using a two step synthesis. Tn the first step cores were prepared, and in the second step the shells were grown using high-temperature pyrolysis of organometallic precursors in a coordinating solvent. Core/shell growth was monitored by absorption and photoluminescence spectroscopy. The band gap shifts to the red upon growth of InP or CdSe shells, while for ZnSe and ZnS shells that have larger band offsets with respect to InAs, the band gap energy is maintained. This behavior is reproduced by band gap energy calculations using a particle within a spherical box model. The photoluminescence quantum yield is quenched in InAs/InP core/shells but increases substantially up to 20% for InAs/CdSe and InAs/ZnSe core/shells. For InAs/ZnS core/shells the enhancement of the photoluminescence quantum yields is smaller, up to 8%. The core/shell nanocrystals were characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, and powder X-ray diffraction. X-ray photoelectron spectroscopy provides evidence for shell growth. The X-ray diffraction peaks shift and narrow upon shell growth, providing evidence for an epitaxial growth mode. Simulations of the X-ray diffraction patterns reproduce both effects, and show that there is one stacking fault present for very four to five layers in the core and core/shell nanocrystals. The stability of InAs/CdSe and InAs/ZnSe core/shells against oxidation is substantially improved compared with the cores, and the photostability is significantly better compared with a typical near-TR laser dye IR140. Core/shell nanocrystals with InAs cores are suggested:as a novel type of fluorophores covering the near-IR spectral range, with high emission quantum yields and improved stability compared with traditional near-TR laser dyes.