Rubidium and Cesium Ion-Induced Electron and Ion Signals for Scanning Ion Microscopy Applications

Area of Science:

• Materials Science
• Physics
• Surface Science

Background:

• Focused Ion Beam (FIB) microscopy is crucial for materials characterization.
• Current FIB systems primarily use Gallium (Ga+) ions.
• Exploring alternative ion sources is essential for advancing imaging capabilities.

Purpose of the Study:

• Investigate the application of novel focused ion beam (FIB) systems utilizing ultracold rubidium (Rb) and cesium (Cs) atoms.
• Compare the imaging performance of Rb+ and Cs+ FIB systems with conventional Ga+ FIB systems.
• Evaluate the merits of Rb+ and Cs+ for enhanced scanning ion microscopy.

Main Methods:

• Utilized ion-induced electron and ion yields to analyze FIB system performance.
• Conducted comparative measurements on Rb+, Cs+, and commercially available Ga+ FIB systems.
• Examined secondary electron (SE) yields and ion-induced ion signals on various pure element targets.

Main Results:

• Rb+ and Cs+ FIB systems demonstrated higher secondary electron (SE) yields compared to Ga+ FIB systems across diverse targets.
• The enhanced SE yields suggest a potential for higher signal-to-noise ratios in SE imaging with Rb+/Cs+.
• Analysis of ion-induced ion signals indicated that secondary ions dominate Cs+ signals, while Rb+ and Ga+ signals contain more backscattered ions.

Conclusions:

• Ultracold Rb+ and Cs+ FIB systems offer significant advantages over Ga+ FIB for secondary electron imaging due to higher yields.
• Rb+ and Cs+ FIB systems have the potential to improve signal-to-noise ratios, enabling more detailed surface analysis.
• Understanding the differences in ion-induced ion signals (secondary vs. backscattered) is key for optimizing FIB applications.