Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200, Australia.
Nano Lett. 2010 Mar 10;10(3):908-15. doi: 10.1021/nl903688v.
Controlling the crystallographic phase purity of III-V nanowires is notoriously difficult, yet this is essential for future nanowire devices. Reported methods for controlling nanowire phase require dopant addition, or a restricted choice of nanowire diameter, and only rarely yield a pure phase. Here we demonstrate that phase-perfect nanowires, of arbitrary diameter, can be achieved simply by tailoring basic growth parameters: temperature and V/III ratio. Phase purity is achieved without sacrificing important specifications of diameter and dopant levels. Pure zinc blende nanowires, free of twin defects, were achieved using a low growth temperature coupled with a high V/III ratio. Conversely, a high growth temperature coupled with a low V/III ratio produced pure wurtzite nanowires free of stacking faults. We present a comprehensive nucleation model to explain the formation of these markedly different crystal phases under these growth conditions. Critical to achieving phase purity are changes in surface energy of the nanowire side facets, which in turn are controlled by the basic growth parameters of temperature and V/III ratio. This ability to tune crystal structure between twin-free zinc blende and stacking-fault-free wurtzite not only will enhance the performance of nanowire devices but also opens new possibilities for engineering nanowire devices, without restrictions on nanowire diameters or doping.
控制 III-V 纳米线的晶体相纯度是出了名的困难，但这对于未来的纳米线器件是至关重要的。已报道的控制纳米线相的方法需要掺杂剂的添加，或者纳米线直径的选择受到限制，而且很少能得到纯相。在这里，我们证明通过简单地调整基本生长参数：温度和 V/III 比，可以实现具有任意直径的、相完全纯净的纳米线。在不牺牲直径和掺杂水平等重要规格的情况下实现了相纯度。通过使用低温和高 V/III 比，可以实现没有孪晶缺陷的纯闪锌矿纳米线。相反，通过高温和低 V/III 比可以生产出没有堆垛层错的纯纤锌矿纳米线。我们提出了一个综合成核模型来解释在这些生长条件下形成这些明显不同的晶体相的过程。实现相纯度的关键是纳米线侧面的表面能发生变化，而这又受到温度和 V/III 比等基本生长参数的控制。这种在无孪晶闪锌矿和无堆垛层错纤锌矿之间调谐晶体结构的能力不仅将提高纳米线器件的性能，而且还为纳米线器件的工程设计开辟了新的可能性，而不受纳米线直径或掺杂的限制。
