Laboratório de Filmes Semicondutores, Universidade Estadual Paulista Bauru , 17033-360 São Paulo, Brazil.
Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany.
Nano Lett. 2017 Jan 11;17(1):63-70. doi: 10.1021/acs.nanolett.6b03249. Epub 2016 Dec 8.
We present a conceptually novel approach to achieve selective area epitaxy of GaN nanowires. The approach is based on the fact that these nanostructures do not form in plasma-assisted molecular beam epitaxy on structurally and chemically uniform cation-polar substrates. By in situ depositing and nitridating Si on a Ga-polar GaN film, we locally reverse the polarity to induce the selective area epitaxy of N-polar GaN nanowires. We show that the nanowire number density can be controlled over several orders of magnitude by varying the amount of predeposited Si. Using this growth approach, we demonstrate the synthesis of single-crystalline and uncoalesced nanowires with diameters as small as 20 nm. The achievement of nanowire number densities low enough to prevent the shadowing of the nanowire sidewalls from the impinging fluxes paves the way for the realization of homogeneous core-shell heterostructures without the need of using ex situ prepatterned substrates.
我们提出了一种新概念性的方法，以实现 GaN 纳米线的选择性区域外延生长。该方法基于以下事实：在结构和化学均匀的阳离子极性衬底上，这些纳米结构不会在等离子体辅助分子束外延中形成。通过在 Ga 极性 GaN 薄膜上原位沉积和氮化 Si，我们局部反转极性以诱导 N 极性 GaN 纳米线的选择性区域外延生长。我们表明，通过改变预沉积 Si 的量，可以在几个数量级上控制纳米线的数密度。使用这种生长方法，我们展示了单晶和未合并的纳米线的合成，其直径小至 20nm。实现足够低的纳米线数密度，以防止纳米线侧壁被入射通量遮蔽，为实现无需要使用外部分形衬底的均匀核壳异质结构铺平了道路。
