Koval Olga Yu, Fedorov Vladimir V, Bolshakov Alexey D, Eliseev Igor E, Fedina Sergey V, Sapunov Georgiy A, Udovenko Stanislav A, Dvoretckaia Liliia N, Kirilenko Demid A, Burkovsky Roman G, Mukhin Ivan S
Nanotechnology Research and Education Centre of the Russian Academy of Sciences, Alferov University, Khlopina 8/3, 194021 Saint Petersburg, Russia.
Institute of Physics, Nanotechnology and Telecommunications, Peter the Great Saint Petersburg Polytechnic University, Politekhnicheskaya 29, 195251 Saint Petersburg, Russia.
Nanomaterials (Basel). 2021 Apr 9;11(4):960. doi: 10.3390/nano11040960.
Control and analysis of the crystal phase in semiconductor nanowires are of high importance due to the new possibilities for strain and band gap engineering for advanced nanoelectronic and nanophotonic devices. In this letter, we report the growth of the self-catalyzed GaP nanowires with a high concentration of wurtzite phase by molecular beam epitaxy on Si (111) and investigate their crystallinity. Varying the growth temperature and V/III flux ratio, we obtained wurtzite polytype segments with thicknesses in the range from several tens to 500 nm, which demonstrates the high potential of the phase bandgap engineering with highly crystalline self-catalyzed phosphide nanowires. The formation of rotational twins and wurtzite polymorph in vertical nanowires was observed through complex approach based on transmission electron microscopy, powder X-ray diffraction, and reciprocal space mapping. The phase composition, volume fraction of the crystalline phases, and wurtzite GaP lattice parameters were analyzed for the nanowires detached from the substrate. It is shown that the wurtzite phase formation occurs only in the vertically-oriented nanowires during vapor-liquid-solid growth, while the wurtzite phase is absent in GaP islands parasitically grown via the vapor-solid mechanism. The proposed approach can be used for the quantitative evaluation of the mean volume fraction of polytypic phase segments in heterostructured nanowires that are highly desirable for the optimization of growth technologies.
由于先进的纳米电子和纳米光子器件在应变和带隙工程方面有了新的可能性，半导体纳米线中晶相的控制和分析具有高度重要性。在本信函中，我们报告了通过分子束外延在Si(111)上生长具有高浓度纤锌矿相的自催化GaP纳米线，并研究了它们的结晶度。通过改变生长温度和V/III通量比，我们获得了厚度在几十到500nm范围内的纤锌矿多型片段，这证明了利用高度结晶的自催化磷化物纳米线进行相带隙工程的巨大潜力。通过基于透射电子显微镜、粉末X射线衍射和倒易空间映射的复杂方法，观察到了垂直纳米线中旋转孪晶和纤锌矿多晶型的形成。对从衬底上分离的纳米线的相组成、晶相的体积分数和纤锌矿GaP晶格参数进行了分析。结果表明，在气-液-固生长过程中，纤锌矿相仅在垂直取向的纳米线中形成，而通过气-固机制寄生生长的GaP岛中不存在纤锌矿相。所提出的方法可用于定量评估异质结构纳米线中多型相片段的平均体积分数，这对于优化生长技术非常必要。
