Nanoscale subsurface characterization technologies based on the scanning electron microscope platform offer incomparable advantages of nondestructiveness and penetration depths up to the micrometer scale. However, the electron beam can serve not just as a mechanical/electrical excitation source but also as an excellent nanoscale thermal excitation source, which can facilitate the development of nanoscale subsurface imaging methods based on the Seebeck effect in semiconducting materials. In this work, a subsurface nondestructive imaging technology, scanning thermoelectric capacitance microscopy (STeCM), was developed based on the interaction between a non-steady-state electron beam and semiconducting materials, exploiting the Seebeck effect. In STeCM, a square wave-modulated hot electron beam with huge kinetic energy excites a “thermal wave” in the subsurface local region of the semiconducting sample. The heated local region, acting as a thermoelectric capacitor, undergoes cyclic charging and discharging, leading to the generation of periodic current due to non-equilibrium carrier migration. The second-order harmonic component of this current is demodulated to visualize embedded local thermal/thermoelectric inhomogeneities. Amazingly, for STeCM sample, only a smooth or polished surface is required, eliminating the need for any microfabrication, which will effectively decrease the configuration difficulty in the experiment. STeCM offers an alternative subsurface nondestructive imaging technology for more efficient, simple, and robust characterization.

中文翻译：

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非稳态电子束驱动扫描热电容显微镜的纳米级次表面成像


基于扫描电子显微镜平台的纳米级亚表面表征技术具有无与伦比的无损性和微米级穿透深度等优势。然而，电子束不仅可以用作机械/电激发源，还可以用作出色的纳米级热激发源，这可以促进半导体材料中基于塞贝克效应的纳米级亚表面成像方法的发展。在这项工作中，利用塞贝克效应，基于非稳态电子束与半导体材料之间的相互作用，开发了一种亚表面无损成像技术，即扫描热电容显微镜 （STeCM）。在 STeCM 中，具有巨大动能的方波调制热电子束在半导体样品的地下局部区域激发“热波”。加热的局部区域，作为热电电容器，进行循环充电和放电，由于非平衡载流子迁移而产生周期性电流。该电流的二阶谐波分量被解调，以可视化嵌入的局部热/热电不均匀性。令人惊讶的是，对于 STeCM 样品，只需要光滑或抛光的表面，无需任何微加工，这将有效降低实验中的配置难度。STeCM 提供了一种替代的地下无损成像技术，可实现更高效、更简单、更稳健的表征。