Azimi Zahra, Gagrani Nikita, Qu Jiangtao, Lem Olivier L C, Mokkapati Sudha, Cairney Julie M, Zheng Rongkun, Tan Hark Hoe, Jagadish Chennupati, Wong-Leung Jennifer
Department of Electronic Materials Engineering, Research School of Physics, The Australian National University, Canberra, Australia.
Nanoscale Horiz. 2021 Jun 28;6(7):559-567. doi: 10.1039/d1nh00079a.
GaAs nanowires are regarded as promising building blocks of future optoelectronic devices. Despite progress, the growth of high optical quality GaAs nanowires is a standing challenge. Understanding the role of twin defects and nanowire facets on the optical emission and minority carrier lifetime of GaAs nanowires is key for the engineering of their optoelectronic properties. Here, we present new insights into the microstructural parameters controlling the optical properties of GaAs nanowires, grown via selective-area metal-organic vapor-phase epitaxy. We observe that these GaAs nanowires have a twinned zinc blende crystal structure with taper-free {110} side facets that result in an ultra-low surface recombination velocity of 3.5 × 104 cm s-1. This is an order of magnitude lower than that reported for defect-free GaAs nanowires grown by the vapor-liquid-solid technique. Using time-resolved photoluminescence and cathodoluminescence measurements, we untangle the local correlation between structural and optical properties demonstrating the superior role of the side facets in determining recombination rates over that played by twin defects. The low surface recombination velocity of these taper-free {110} side facets enable us to demonstrate, for the first time, low-temperature lasing from bare (unpassivated) GaAs nanowires, and also efficient room-temperature lasing after passivation with an AlGaAs shell.
砷化镓纳米线被视为未来光电器件的有前途的构建块。尽管取得了进展，但生长高质量光学性能的砷化镓纳米线仍然是一个长期挑战。了解孪晶缺陷和纳米线晶面在砷化镓纳米线的光发射和少数载流子寿命方面的作用，是其光电子性能工程的关键。在这里，我们展示了对通过选择性区域金属有机气相外延生长的砷化镓纳米线光学性能控制的微观结构参数的新见解。我们观察到这些砷化镓纳米线具有孪晶闪锌矿晶体结构，其无锥度的{110}侧面导致超低表面复合速度为3.5×10⁴厘米/秒。这比通过气液固技术生长的无缺陷砷化镓纳米线报道的速度低一个数量级。通过时间分辨光致发光和阴极发光测量，我们解开了结构和光学性能之间的局部相关性，证明了侧面在决定复合速率方面比孪晶缺陷发挥着更重要的作用。这些无锥度的{110}侧面的低表面复合速度使我们首次展示了裸（未钝化）砷化镓纳米线的低温激光发射，以及用AlGaAs壳层钝化后的高效室温激光发射。
