Jonas Lähnemann, Pierre Corfdir, Felix Feix, Jumpei Kamimura, Timur Flissikowski, Holger T. Grahn, Lutz Geelhaar, and Oliver Brandt
备注：
This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Nano Letters (2016), copyright (C) American Chemical Society after peer review. To access the final edited and published work see http://dx.doi.org/10.1021/acs.nanolett.5b03748
研究了用分子束外延技术在Si衬底上生长的低In含量（x<0.2）的非故意掺杂和Si掺杂的In $_x$ Ga $_{1-x}$ N纳米线的发光特性。在300 K下观察到的发射带从无意掺杂的样品是集中在低得多的能量（800毫电子伏）比预期的X-射线衍射法和能量色散X-射线光谱测量的In含量。这种差异源于纳米线侧壁处费米能级的钉扎，这引起强径向内建电场。内置的电场与（In，Ga）N合金固有的成分波动的组合诱导空间直接和间接复合通道之间的竞争。在高温下，纳米线核心的电子与靠近表面的空穴重新结合，无意掺杂的纳米线的发射表现出数百meV的斯塔克位移。空间直接和间接跃迁之间的竞争进行了分析，作为一个函数的温度与各种Si浓度的样品。我们认为径向斯塔克效应是导致（In，Ga）N纳米线在整个可见光范围内的宽带吸收的原因，这使得这些纳米结构成为太阳能应用的一个有前途的平台。
英文摘要：
We study the luminescence of unintentionally doped and Si-doped In$_x$Ga$_{1-x}$N nanowires with a low In content (x<0.2) grown by molecular beam epitaxy on Si substrates. The emission band observed at 300 K from the unintentionally doped samples is centered at much lower energies (800 meV) than expected from the In content measured by x-ray diffractometry and energy dispersive x-ray spectroscopy. This discrepancy arises from the pinning of the Fermi level at the sidewalls of the nanowires, which gives rise to strong radial built-in electric fields. The combination of the built-in electric fields with the compositional fluctuations inherent to (In,Ga)N alloys induces a competition between spatially direct and indirect recombination channels. At elevated temperatures, electrons at the core of the nanowire recombine with holes close to the surface, and the emission from unintentionally doped nanowires exhibits a Stark shift of several hundreds of meV. The competition between spatially direct and indirect transitions is analyzed as a function of temperature for samples with various Si concentrations. We propose that the radial Stark effect is responsible for the broadband absorption of (In,Ga)N nanowires across the entire visible range, which makes these nanostructures a promising platform for solar energy applications.
Effective separation of photogenerated electron-hole pairs by radial field facilitates ultrahigh photoresponse in single semiconductor nanowire photodetectors
Domain Morphology, Electrocaloric Response, and Negative Capacitance States of Ferroelectric Nanowires Array
Institute of Physics, National Academy of Sciences of Ukraine（乌克兰国家科学院物理研究所）；Taras Shevchenko National University of Kyiv（基辅塔拉斯舍甫琴科国立大学）；V. Lashkariov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine（乌克兰国家科学院V.拉什卡廖夫半导体物理研究所）；Slovenia Jožef Stefan Institute（斯洛文尼亚约瑟夫斯蒂芬研究所）；Frantsevich Institute for Problems in Materials Science, National Academy of Sciences of Ukraine（乌克兰国家科学院弗兰采维奇材料科学问题研究所）；Zone 5 Technologies（Zone 5科技有限公司）
