Nanowire chip-based electrical and optical devices such as biochemical sensors, physical detectors, or light emitters combine outstanding functionality with a small footprint, reducing expensive material and energy consumption. The core functionality of many nanowire-based devices is embedded in their p-n junctions. To fully unleash their potential, such nanowire-based devices require – besides a high performance – stability and reliability. Here, we report on an axial p-n junction GaAs nanowire X-ray detector that enables ultra-high spatial resolution (~200 nm) compared to micron scale conventional ones. In-operando X-ray analytical techniques based on a focused synchrotron X-ray nanobeam allow probing the internal electrical field and observing hot electron effects at the nanoscale. Finally, we study device stability and find a selective hot electron induced oxidization in the n-doped segment of the p-n junction. Our findings demonstrate capabilities and limitations of p-n junction nanowires, providing insight for further improvement and eventual integration into on-chip devices.

基于纳米线芯片的电气和光学设备，例如生化传感器、物理探测器或光发射器，将出色的功能与小尺寸相结合，减少了昂贵的材料和能源消耗。许多基于纳米线的器件的核心功能嵌入在它们的 pn 结中。为了充分发挥其潜力，这种基于纳米线的设备除了高性能之外还需要稳定性和可靠性。在这里，我们报告了一种轴向 pn 结 GaAs 纳米线 X 射线探测器，与微米级传统探测器相比，它具有超高的空间分辨率（~200 nm）。基于聚焦同步加速器 X 射线纳米束的操作中 X 射线分析技术允许探测内部电场并观察纳米级的热电子效应。最后，我们研究了器件稳定性，并在 pn 结的 n 掺杂部分发现了选择性热电子诱导氧化。我们的发现证明了 pn 结纳米线的能力和局限性，为进一步改进和最终集成到片上设备提供了见解。