Institut d'Electronique Fondamentale, UMR CNRS 8622, University Paris Sud 11, 91405 Orsay Cedex, France.
Nanotechnology. 2012 Jul 5;23(26):265402. doi: 10.1088/0957-4484/23/26/265402. Epub 2012 Jun 15.
We report on the growth and electro-optical studies of photovoltaic properties of GaAsP nanowires. Low density GaAsP nanowires were grown by Au assisted MOVPE on Si(001) substrates using a two step procedure to form a radial p-n junction. The STEM analyses show that the nanowires have cubic structure with the alloy composition GaAs₀.₈₈P₀.₁₂ in the nanowire core and GaAs₀.₇₆P₀.₂₄ in the shell. The nanowire ensembles were processed in the form of sub-millimeter size mesas. The photovoltaic properties were characterized by optical beam induced current (OBIC) and electronic beam induced current (EBIC) maps. Both OBIC and EBIC maps show that the photovoltage is generated by the nanowires; however, a strong signal variation from wire to wire is observed. Only one out of six connected nanowires produce a measurable signal. These strong fluctuations can be tentatively explained by the variation of the resistance of the nanowire-to-substrate connection, which is highly sensitive to the quality of the Si-GaAsP interface. This study demonstrates the importance of the spatially resolved charge collection microscopy techniques for the diagnosis of failures in nanowire photovoltaic devices.
我们报告了 GaAsP 纳米线的生长和光电性能的光伏研究。通过 Au 辅助 MOVPE 在 Si(001)衬底上使用两步法生长低密度 GaAsP 纳米线，以形成径向 p-n 结。STEM 分析表明，纳米线具有立方结构，纳米线核中的合金组分为 GaAs₀.₈₈P₀.₁₂，壳中的合金组分为 GaAs₀.₇₆P₀.₂₄。纳米线组件被加工成亚毫米大小的台面。通过光致光束电流（OBIC）和电子束电流（EBIC）映射来表征光伏性能。OBIC 和 EBIC 图谱均表明，纳米线产生光电压；然而，从一根纳米线到另一根纳米线的信号变化很大。在六个连接的纳米线中，只有一个产生可测量的信号。这些强烈的波动可以通过纳米线与衬底连接电阻的变化来解释，纳米线与衬底连接电阻对 Si-GaAsP 界面的质量非常敏感。这项研究证明了空间分辨电荷收集显微镜技术对于诊断纳米线光伏器件故障的重要性。
