Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom.
Nano Lett. 2012 Oct 10;12(10):5269-74. doi: 10.1021/nl302490y. Epub 2012 Sep 24.
We realize the growth of self-catalyzed core-shell GaAs/GaAsP nanowires (NWs) on Si substrates using molecular-beam epitaxy. Transmission electron microscopy of single GaAs/GaAsP NWs demonstrates their high crystal quality and shows domination of the GaAs zinc-blende phase. Using continuous-wave and time-resolved photoluminescence (PL), we make a detailed comparison with uncapped GaAs NWs to emphasize the effect of the GaAsP capping in suppressing the nonradiative surface states. Significant PL enhancement in the core-shell structures exceeding 3 orders of magnitude at 10 K is observed; in uncapped NWs PL is quenched at 60 K, whereas single core-shell GaAs/GaAsP structures exhibit bright emission even at room temperature. From analysis of the PL temperature dependence in both types of NW we are able to determine the main carrier escape mechanisms leading to the PL quench.
我们使用分子束外延法实现了在 Si 衬底上自催化生长的 GaAs/GaAsP 核壳纳米线（NWs）的生长。对单个 GaAs/GaAsP NWs 的透射电子显微镜分析表明其具有高晶体质量，并显示出 GaAs 闪锌矿相的主导地位。通过连续波和时间分辨光致发光（PL），我们与未覆盖的 GaAs NWs 进行了详细比较，以强调 GaAsP 覆盖层在抑制非辐射表面态方面的作用。在 10 K 下，观察到核壳结构中的 PL 增强超过 3 个数量级；在未覆盖的 NWs 中，PL 在 60 K 时被猝灭，而单个核壳 GaAs/GaAsP 结构即使在室温下也表现出明亮的发射。通过对两种 NW 的 PL 温度依赖性的分析，我们能够确定导致 PL 猝灭的主要载流子逃逸机制。
