Dubrovskii Vladimir G, Kim Wonjong, Piazza Valerio, Güniat Lucas, Fontcuberta I Morral Anna
Faculty of Physics, St. Petersburg State University, Universitetskaya Embankment 13B, 199034 St. Petersburg, Russia.
Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
Nano Lett. 2021 Apr 14;21(7):3139-3145. doi: 10.1021/acs.nanolett.1c00349. Epub 2021 Apr 5.
Selective area epitaxy constitutes a mainstream method to obtain reproducible nanomaterials. As a counterpart, self-assembly allows their growth without costly substrate preparation, with the drawback of uncontrolled positioning. We propose a mixed approach in which self-assembly is limited to reduced regions on a patterned silicon substrate. While nanowires grow with a wide distribution of diameters, we note a mostly binary occurrence of crystal phases. Self-catalyzed GaAs nanowires form in either a wurtzite or zincblende phase in the same growth run. Quite surprisingly, thicker nanowires are wurtzite and thinner nanowires are zincblende, while the common view predicts the reverse trend. We relate this phenomenon to the influx of Ga adatoms by surface diffusion, which results in different contact angles of Ga droplets. We demonstrate the wurtzite phase of thick GaAs NWs up to 200 nm in diameter in the Au-free approach, which has not been achieved so far to our knowledge.
选择性区域外延是获得可重复纳米材料的主流方法。相比之下，自组装可在无需昂贵衬底制备的情况下实现其生长，但其缺点是位置不受控制。我们提出了一种混合方法，其中自组装被限制在图案化硅衬底上的缩小区域。虽然纳米线生长时直径分布很广，但我们注意到晶体相大多以二元形式出现。在同一生长过程中，自催化生长的GaAs纳米线会形成纤锌矿相或闪锌矿相。相当令人惊讶的是，较粗的纳米线是纤锌矿相，较细的纳米线是闪锌矿相，而通常的观点预测的是相反的趋势。我们将这种现象与通过表面扩散的Ga吸附原子的流入联系起来，这导致了Ga液滴的不同接触角。我们在无金方法中展示了直径达200 nm的粗GaAs纳米线的纤锌矿相，据我们所知，这是目前尚未实现的。
