Abstract：
Vertically grown nanowires (NWs) are a research interest in optoelectronics and photovoltaic applications due to their high surface to volume ratio and good light trapping capabilities. This study presents the effects of process and design parameters on self-catalyzed GaAsSbN NWs grown by plasma-assisted molecular beam epitaxy on patterned silicon substrates using electron beam lithography. Vertical alignment of the patterned NWs examined via scanning electron microscopy show the sensitivity of patterned NW growth to the parameters of NW diameter, pitch, dose time, etching techniques and growth plan. Diameters range from 90 nm to 250 nm. Pitch lengths of 200 nm, 400 nm, 600 nm, 800 nm, 1000 nm, and 1200 nm were examined. Dry etching of the oxide layer of the silicon substrate and PMMA coating is performed using reactive ion etching (RIE) for 20 s and 120 s respectively. Comparisons of different HF etch durations performed pre and post PMMA removal are presented. Additionally, the report of an observed surfactant effect in dilute nitride GaAsSbN NWs in comparison to non-nitride GaAsSb is presented. Optimizations to patterning, RIE, and HF etching are presented to obtain higher vertical yield of patterned GaAsSbN NWs, achieving ∼80% of the expected NWµm2. Room temperature and 4 K photoluminescence results show the effect of nitride incorporation for further bandgap tuning, and patterned pitch on the optical characteristics of the NWs which gives insights to the compositional homogeneity for NWs grown at each pitch length.
摘要：
垂直生长的纳米线由于其高的表面体积比和良好的光捕获能力而在光电子和光伏应用中具有研究兴趣。这项研究介绍了工艺和设计参数对自催化GaAsSbN纳米线（NWs）的影响，该纳米线是通过电子束光刻在图案化的硅衬底上通过等离子体辅助分子束外延生长的。通过扫描电子显微镜检查的图案化NW的垂直排列显示图案化纳米线生长对纳米线直径参数的敏感性，螺距,剂量时间，刻蚀技巧和成长计划。直径范围从90nm到250nm。200nm的间距长度，400nm,600nm,800nm,1000nm,和1200nm进行检查。使用反应离子蚀刻分别对硅基板和PMMA涂层的氧化物层进行干蚀刻20s和120s。给出了在PMMA去除之前和之后执行的不同HF蚀刻持续时间的比较。此外,报告了与非氮化物GaAsSb相比，在稀氮化物GaAsSbN纳米线中观察到的表面活性剂效应。优化图案，反应离子蚀刻，和HF蚀刻，以获得更高的垂直产量的图案化GaAsSbN纳米线，达到预期NW/µm2的80%。室温和4K光致发光结果表明，氮化物掺入对进一步带隙调谐的影响，以及纳米线的光学特性上的图案化间距，这可以洞悉在每个间距长度处生长的纳米线的组成均匀性。
