Scanning electron microscopy (SEM) has been widely used to evaluate nanoscale images of materials and devices by measuring the current of secondary electrons (SEs). We developed scanning ultrafast electron microscopy by combining a commercially available SEM and a femtosecond laser to reveal the local dynamic properties of broadband electric devices during operation. We conducted pump–probe experiments and successfully visualized the distribution of electric potential on the electrodes of a photoconductive antenna during a transient response induced by optical excitation of photocarriers in the semiconductor substrate of the device. The temporal resolution was determined to be 43 ps based on the pulse duration of the primary electrons under the space charge effect. The observed waveform of the SE current exhibited several phenomena, including ultrafast carrier dynamics at the boundaries, carrier lifetime, and electric circuit response. The proposed technique is expected to provide a new method for visualizing the operation of high-frequency electronic devices.

中文翻译：

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使用扫描超快电子显微镜可视化光电导天线上局部电势的瞬态响应

扫描电子显微镜 (SEM) 已广泛用于通过测量二次电子 (SE) 电流来评估材料和器件的纳米级图像。我们通过结合商用 SEM 和飞秒激光器开发了扫描超快电子显微镜，以揭示宽带电子器件在运行过程中的局部动态特性。我们进行了泵浦探针实验，并成功地可视化了光电导天线电极上的电势分布，该分布是由器件半导体基板中光载流子的光激发引起的瞬态响应。根据空间电荷效应下初级电子的脉冲持续时间，确定时间分辨率为 43 ps。观察到的 SE 电流波形表现出多种现象，包括边界处的超快载流子动力学、载流子寿命和电路响应。所提出的技术有望提供一种可视化高频电子设备操作的新方法。