Properties of GaN Nanowires Grown by Molecular Beam Epitaxy
Properties of GaN Nanowires Grown by Molecular Beam Epitaxy
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DOI：
10.1109/jstqe.2010.2098396
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发表时间：
2011-07-01
影响因子：
4.9
通讯作者：
Riechert, Henning
中科院分区：
文献类型：
--
作者：
Geelhaar, Lutz;Cheze, Caroline;Riechert, Henning
OnSi(1 1 1)和Si(0 0 1)，GaN纳米线(NWS)是以自诱导方式形成的，不需要任何外部材料。在蓝宝石上，镍捕收剂诱导了NW生长。这两种纳米晶均为纤锌矿结构，沿垂直于衬底的Ga极C方向生长。虽然在Ni诱导的NW面上，如果生长温度较低，也会形成A面段，但NW侧壁是M平面小面。自诱导和集电极诱导的NW都是无应变的，并与衬底外延取向，但特别是前者表现出显著的倾斜和扭转扩散，这是由于Si-N界面层基本上是非晶态的。自感生NWS基本上没有扩展缺陷，而集电极感生NWS包含许多层错。前者的光致发光明显更亮、更锐利。单个的、分散的、自感生的原子核的光谱包含非常尖锐的激子线。大量的发射是由与靠近表面的施主结合的激子引起的，这些激子的结合能与体值相比降低。相比较而言，自感生纳米晶的微观结构和光学性能均优于自诱导纳米晶。收集器诱导的NWS的有限材料质量可以用收集器的不利影响来解释。
OnSi(1 1 1) and Si(0 0 1), GaN nanowires (NWs) form in a self-induced way without the need for any external material. On sapphire, NW growth is induced by Ni collectors. Both types of NWs exhibit the wurtzite crystal structure and grow in the Ga-polar C-direction perpendicular to the substrate. The NW sidewalls are M-plane facets, although on the Ni-induced NWs also A-plane segments form, if the growth temperature is low. Both self-induced and collector-induced NWs are free of strain and epitaxially aligned to the substrate, but in particular the former show a significant spread in tilt and twist caused by a mostly amorphous interfacial layer of Si-N. The self-induced NWs are virtually free of extended defects, but the collector-induced NWs contain many stacking faults. The photoluminescence of the former is significantly brighter and sharper. The spectra of single, dispersed, self-induced NWs contain extremely sharp excitonic lines. Significant emission is caused by excitons bound to donors close to the surface whose binding energy is reduced compared to the bulk value. In comparison, both the microstructure and optical properties of the self-induced NWs are superior. The limited material quality of the collector-induced NWs can be explained by detrimental effects of the collector.