A Story Told by a Single Nanowire: Optical Properties of Wurtzite GaAs
A Story Told by a Single Nanowire: Optical Properties of Wurtzite GaAs
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DOI：
10.1021/nl3025714
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发表时间：
2012-12-01
期刊：
影响因子：
10.8
通讯作者：
Weman, Helge
中科院分区：
文献类型：
--
作者：
Ahtapodov, Lyubomir;Todorovic, Jelena;Weman, Helge
纳米线 (NW) 中发现的纤锌矿 (WZ) GaAs 晶相的光学性质是一个备受争议的话题。在这里，我们研究了通过金辅助分子束外延 (MBE)、显微光致发光光谱 (mu-PL) 和（扫描）透射电子显微镜在同一根单线上生长的高质量纯 WZ GaAs/AlGaAs 核壳纳米线。我们确定室温 (294 K) WZ GaAs 带隙为 1.444 eV，比闪锌矿 (ZB) GaAs 大 20 meV，并表明 15 K 时的自由激子发射为 1.516 eV。基于时间和温度分辨的 mu-PL 结果，我们提出了 WZ GaAs 中的 Gamma(8) 导带对称性。我们提出了一种量化纳米线光学质量的方法，考虑到室温和低温集成PL强度之间的差异，并证明Au辅助的GaAs/AlGaAs核壳纳米线在室温下可以具有高PL亮度。
The optical properties of the wurtzite (WZ) GaAs crystal phase found in nanowires (NWs) are a highly controversial topic. Here, we study high-quality pure WZ GaAs/AlGaAs core-shell NWs grown by Au-assisted molecular beam epitaxy (MBE) with microphotoluminescence spectroscopy (mu-PL) and (scanning) transmission electron microscopy on the very same single wire. We determine the room temperature (294 K) WZ GaAs bandgap to be 1.444 eV, which is similar to 20 meV larger than in zinc blende (ZB) GaAs, and show that the free exciton emission at 15 K is at 1.516 eV. On the basis of time- and temperature-resolved mu-PL results, we propose a Gamma(8) conduction band symmetry in WZ GaAs. We suggest a method for quantifying the optical quality of NWs, taking into consideration the difference between the room and low temperature integrated PL intensity, and demonstrate that Au-assisted GaAs/AlGaAs core-shell NWs can have high PL brightness up to room temperature.