Spatially resolved analysis of dopant concentration in axial GaAs NW pn-contacts
Spatially resolved analysis of dopant concentration in axial GaAs NW pn-contacts
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DOI：
10.1016/j.solmat.2019.03.049
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发表时间：
2019-08
影响因子：
6.9
通讯作者：
A. Nägelein;C. Timm;K. Schwarzburg;M. Steidl;P. Kleinschmidt;T. Hannappel
中科院分区：
文献类型：
--
作者：
A. Nägelein;C. Timm;K. Schwarzburg;M. Steidl;P. Kleinschmidt;T. Hannappel
新型光电器件的效率，例如太阳能电池关键取决于控制器件中的掺杂水平。通过采用纳米线来减小结构尺寸具有多种吸引力，例如降低材料成本，但使表征更具挑战性。对于纳米结构中的掺杂浓度，仍然缺乏精确且同时快速的表征技术。在这项工作中，通过利用多尖端扫描隧道显微镜 (MT-STM) 作为四点探针，对 GaAs-NW 的轴向 pn 结进行了电研究。此外，在室温下通过光致发光（PL）和阴极发光（CL）显微镜光谱对这些纳米线进行了光学探测。通过这两种方法，我们能够获得纳米结构的补充信息并绘制出完整的图片。通过使用考虑了 Burstein-Moss 位移和带隙变窄的输运模型（对于 MT-STM）和半经验方程（对于 PL 和 CL），评估和比较了纳米线的掺杂浓度。解决了 n 掺杂 NW 顶部电子浓度的轴向变化以及 p 掺杂 NW 基极中恒定的空穴浓度。我们证明，这两种技术的结合对于改进用于通过发光数据估计掺杂分布的合适且精确的模型的开发是必要的。
The efficiency of novel opto-electronic devices e.g. solar cells crucially depends on controlling the doping levels in the device. Decreasing the size of the structure by employing nanowires is attractive for several reasons, for instance reduced material costs, but makes the characterization more challenging. There is still a lack of a precise and simultaneously rapid characterization technique for doping concentrations in nanostructures. In this work axial pn-junctions of GaAs-NWs were investigated electrically, by the utilization of a multi-tip scanning tunneling microscope (MT-STM) as a four point prober. Additionally, these NWs were probed optically at room-temperature by photoluminescence (PL) and cathodoluminescence (CL) microscopy spectroscopy. With both approaches we were able to achieve complementary information of the nanostructure and have developed a complete picture. By using a transport model (for MT-STM) and semi-empirical equations (for PL & CL) which take the Burstein-Moss shift and the band gap narrowing into account, the doping concentrations of the NWs were evaluated and compared. An axial variation in the electron concentration of the n-doped NW-top was resolved as well as a constant hole concentration in the p-doped NW-base. We demonstrate that the combination of both techniques will be necessary to improve the development of a suitable and precise model for the estimation of doping profiles by luminescence data.