基于邻近激子传感的二维半导体光学电压轮廓成像

中文摘要 AI 辅助

原子级薄半导体中的高接触电阻常常掩盖其本征电输运特性，尤其是在出现奇异关联态的低载流子密度区域。我们提出光学电压轮廓成像技术，这是一种无创宽场技术，用邻近的单层MoSe₂激子传感器替代局部电压探针。该传感器被薄六方氮化硼隔离，将目标的局部静电势转化为激子反射率的空间分辨调制。通过逐像素原位校准，这些信号可生成有源偏置半导体器件的定量二维电压图。利用该方法，我们在双层MoSe₂中展示了载流子密度驱动的金属-绝缘体转变，尽管金属区域的两端电阻达兆欧级，但获得的沟道电阻低于1千欧。光学推导的电阻在电阻量子h/e²附近呈现金属-绝缘体交叉，电压图和重构的局部电导率揭示了绝缘和金属区域中显著的空间异质性。该技术除了能在高接触电阻条件下解析沟道电阻外，还能实现对功能性范德华器件中微观输运异质性的空间分辨探测。

英文摘要

High contact resistances in atomically thin semiconductors often mask intrinsic electrical transport properties, particularly at low carrier densities where exotic correlated states emerge. We introduce optical voltage profiling, a noninvasive wide-field technique that replaces local voltage probes with a proximal monolayer MoSe$_2$ exciton sensor. Isolated by thin hexagonal boron nitride, this sensor converts the target's local electrostatic potential into spatially resolved modulations of exciton reflectance. Through pixel-wise in situ calibration, these signals yield quantitative two-dimensional voltage maps of an actively biased semiconductor device. Using this method, we demonstrate the carrier-density-driven metal-insulator transition in bilayer MoSe$_2$ and obtain channel resistances below 1 k$Ω$ despite M$Ω$-scale two-terminal resistances in the metallic region. The optically derived resistance exhibits a metal-insulator crossover near the resistance quantum $h/e^2$, and the voltage maps and reconstructed local conductivity reveal pronounced spatial heterogeneity in both insulating and metallic regimes. Beyond resolving channel resistance under high contact-resistance conditions, the technique provides spatially resolved access to microscopic transport heterogeneity in functional van der Waals devices.

发表机构

• University of California, Berkeley（加州大学伯克利分校）
• Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）
• Kavli Energy NanoScience Institute（卡弗里纳米科学能源研究所）
• National Institute for Materials Science（材料科学国立研究所）

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