期刊
NANO LETTERS
卷 21, 期 21, 页码 9012-9020出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.1c02353
关键词
scattering-type scanning near-field optical microscopy; free-electron laser; phase change material; Kelvin probe force microscopy; GST; optical switching; metavalent bonding
类别
资金
- Deutsche Forschungsgesellschaft (DFG) within the collaborative research center [SFB 917]
- BMBF [05K16ODA, 05K19ODB]
- Wurzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter (ct.qmat)
- TU Dresden graduate academy
Chalcogenide phase change materials can reversibly switch between non-volatile states with vastly different optical properties, enabling novel active nanophotonic devices. In this study, infrared scattering-type scanning near-field optical microscopy (SNOM) and Kelvin probe force microscopy (KPFM) were used to investigate four states of laser-switched Ge3Sb2Te6 with nanometer lateral resolution. The research found that SNOM is sensitive to differences between crystalline and amorphous states, while KPFM has higher sensitivity to changes introduced by melt-quenching.
Chalcogenide phase change materials reversibly switch between non-volatile states with vastly different optical properties, enabling novel active nanophotonic devices. However, a fundamental understanding of their laser-switching behavior is lacking and the resulting local optical properties are unclear at the nanoscale. Here, we combine infrared scattering-type scanning near-field optical microscopy (SNOM) and Kelvin probe force microscopy (KPFM) to investigate four states of laser-switched Ge3Sb2Te6 (as-deposited amorphous, crystallized, reamorphized, and recrystallized) with nanometer lateral resolution. We find SNOM to be especially sensitive to differences between crystalline and amorphous states, while KPFM has higher sensitivity to changes introduced by melt-quenching. Using illumination from a free-electron laser, we use the higher sensitivity to free charge carriers of far-infrared (THz) SNOM compared to mid-infrared SNOM and find evidence that the local conductivity of crystalline states depends on the switching process. This insight into the local switching of optical properties is essential for developing active nanophotonic devices.
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