Nanoscale 3D Tomography by In-Flight Fluorescence Spectroscopy of Atoms Sputtered by a Focused Ion Beam

Nanoscale fabrication and characterization techniques critically underpin a vast range of fields, including nanoelectronics and nanobiotechnology. Focused ion beam (FIB) techniques are appealing due to their high spatial resolution and widespread use for processing of nanostructured materials. Here, we introduce FIB-induced fluorescence spectroscopy (FIB-FS) as a nanoscale technique for spectroscopic detection of atoms sputtered by an ion beam. We use semiconductor heterostructures to demonstrate nanoscale lateral and depth resolution and show that it is limited by ion-induced intermixing of nanostructured materials. Sensitivity is demonstrated qualitatively by depth profiling of 3.5, 5, and 8 nm quantum wells and quantitatively by detection of trace-level impurities present at parts per-million levels. The utility of the FIB-FS technique is demonstrated by characterization of quantum wells and Li-ion batteries. Our work introduces FIB-FS as a high-resolution, high-sensitivity, 3D analysis and tomography technique that combines the versatility of FIB nanofabrication techniques with the power of diffraction-unlimited fluorescence spectroscopy.

Automated summary

Nanoscale fabrication and characterization techniques are crucial for various fields, including nanoelectronics and nanobiotechnology. Focused ion beam (FIB) techniques are attractive due to their high spatial resolution and widespread use in processing nanostructured materials. In this study, we introduce FIB-induced fluorescence spectroscopy (FIB-FS) as a nanoscale technique for spectroscopic detection of ion-beam sputtered atoms. We demonstrate the nanoscale lateral and depth resolution using semiconductor heterostructures, and show that the resolution is limited by ion-induced intermixing of nanostructured materials. We also demonstrate the sensitivity of FIB-FS by depth profiling of quantum wells and detection of trace-level impurities. The utility of FIB-FS is demonstrated in the characterization of quantum wells and Li-ion batteries, combining the versatility of FIB nanofabrication techniques with the power of diffraction-unlimited fluorescence spectroscopy.