Preparation Techniques for Cross-Section Transmission Electron Microscopy Lamellas Suitable for Investigating In Situ Silicon-Aluminum Alloying at Grain Boundaries in Multicrystalline Silicon

摘要

Herein, advanced preparation methods of cross-section samples suitable for site-specific studies of alloying processes are reported. To follow alloying processes in real time with the highest possible spatial resolution, in situ heating transmission electron microscopy (TEM) is conducted. As an industrially relevant model system, aluminum (Al) on multicrystalline silicon (mc-Si) is chosen. Despite the tremendous advantages of in situ TEM compared with ex situ techniques, the development of suitable sample preparation recipes is a challenging task. As the standard focused ion beam (FIB) lift-out fails for this preparation, three alternative methods are implemented. They show significant improvements compared with the widely used standard lift-out and are described and evaluated in terms of contamination and overall lamella quality. Moreover, further improvements are discussed, leading to the conclusion that the new methods allow the reproducible preparation of lamellas suitable for site-specific, in situ TEM alloying experiments.