Peña Román Ricardo Javier, Auad Yves, Grasso Lucas, Padilha Lazaro A, Alvarez Fernando, Barcelos Ingrid David, Kociak Mathieu, Zagonel Luiz Fernando
"Gleb Wataghin" Institute of Physics, University of Campinas-UNICAMP, 13083-859 Campinas, SP, Brazil.
Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), 13083-970 Campinas, SP, Brazil.
Rev Sci Instrum. 2022 Apr 1;93(4):043704. doi: 10.1063/5.0078423.
We present the design, implementation, and illustrative results of a light collection/injection strategy based on an off-axis parabolic mirror collector for a low-temperature Scanning Tunneling Microscope (STM). This device allows us to perform STM induced Light Emission (STM-LE) and Cathodoluminescence (STM-CL) experiments and in situ Photoluminescence (PL) and Raman spectroscopy as complementary techniques. Considering the Étendue conservation and using an off-axis parabolic mirror, it is possible to design a light collection and injection system that displays 72% of collection efficiency (considering the hemisphere above the sample surface) while maintaining high spectral resolution and minimizing signal loss. The performance of the STM is tested by atomically resolved images and scanning tunneling spectroscopy results on standard sample surfaces. The capabilities of our system are demonstrated by performing STM-LE on metallic surfaces and two-dimensional semiconducting samples, observing both plasmonic and excitonic emissions. In addition, we carried out in situ PL measurements on semiconducting monolayers and quantum dots and in situ Raman on graphite and hexagonal boron nitride (h-BN) samples. Additionally, STM-CL and PL were obtained on monolayer h-BN gathering luminescence spectra that are typically associated with intragap states related to carbon defects. The results show that the flexible and efficient light injection and collection device based on an off-axis parabolic mirror is a powerful tool to study several types of nanostructures with multiple spectroscopic techniques in correlation with their morphology at the atomic scale and electronic structure.
我们展示了一种基于离轴抛物面镜收集器的用于低温扫描隧道显微镜（STM）的光收集/注入策略的设计、实现及示例结果。该装置使我们能够进行STM诱导发光（STM - LE）和阴极发光（STM - CL）实验，以及原位光致发光（PL）和拉曼光谱，作为互补技术。考虑到光学扩展量守恒并使用离轴抛物面镜，可以设计一种光收集和注入系统，该系统在保持高光谱分辨率并使信号损失最小化的同时，显示出72%的收集效率（考虑样品表面上方的半球）。通过在标准样品表面上的原子分辨图像和扫描隧道光谱结果来测试STM的性能。我们的系统功能通过在金属表面和二维半导体样品上进行STM - LE得以证明，观察到了等离子体激元和激子发射。此外，我们对半导体单层和量子点进行了原位PL测量，对石墨和六方氮化硼（h - BN）样品进行了原位拉曼测量。另外，在单层h - BN上获得了STM - CL和PL，收集到了通常与碳缺陷相关的带隙内态的发光光谱。结果表明，基于离轴抛物面镜的灵活高效的光注入和收集装置是一种强大的工具，可用于利用多种光谱技术研究几种类型的纳米结构，并将其与原子尺度的形态和电子结构相关联。
