van Treeck David, Ledig Johannes, Scholz Gregor, Lähnemann Jonas, Musolino Mattia, Tahraoui Abbes, Brandt Oliver, Waag Andreas, Riechert Henning, Geelhaar Lutz
Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., Hausvogteiplatz 5-7, 10117 Berlin, Germany.
Institut für Halbleitertechnik, TU Braunschweig, Hans-Sommer-Str. 66, 38106 Braunschweig, Germany.
Beilstein J Nanotechnol. 2019 Jun 5;10:1177-1187. doi: 10.3762/bjnano.10.117. eCollection 2019.
We present the combined analysis of electroluminescence (EL) and current-voltage (-) behavior of single, freestanding (In,Ga)N/GaN nanowire (NW) light-emitting diodes (LEDs) in an unprocessed, self-assembled ensemble grown by molecular beam epitaxy. The data were acquired in a scanning electron microscope equipped with a micromanipulator and a luminescence detection system. Single NW spectra consist of emission lines originating from different quantum wells, and the width of the spectra increases with decreasing peak emission energy. The corresponding - characteristics are described well by a modified Shockley equation. The key advantage of this measurement approach is the possibility to correlate the EL intensity of a single-NW LED with the actual current density in this NW. This way, the external quantum efficiency (EQE) can be investigated as a function of the current in a single-NW LED. The comparison of the EQE characteristic of single NWs and the ensemble device allows for a quite accurate determination of the actual number of emitting NWs in the working ensemble LED and the respective current densities in its individual NWs. This information is decisive for a meaningful and comprehensive characterization of a NW ensemble device, rendering the measurement approach employed here a very powerful analysis tool.
我们展示了通过分子束外延生长的未经处理的自组装单根独立（In，Ga）N/GaN纳米线（NW）发光二极管（LED）的电致发光（EL）和电流-电压（I-V）行为的联合分析。数据是在配备了微操纵器和发光检测系统的扫描电子显微镜中获取的。单根NW光谱由源自不同量子阱的发射线组成，并且光谱宽度随着峰值发射能量的降低而增加。相应的I-V特性可以用修正的肖克利方程很好地描述。这种测量方法的关键优势在于能够将单根NW LED的EL强度与该NW中的实际电流密度相关联。通过这种方式，可以研究单根NW LED中外部量子效率（EQE）与电流的函数关系。单根NW的EQE特性与整体器件的比较使得能够相当准确地确定工作的整体LED中实际发光NW的数量及其各个NW中的相应电流密度。这些信息对于有意义且全面地表征NW整体器件至关重要，使得这里采用的测量方法成为一种非常强大的分析工具。
