Advanced preparation of plan-view specimens on a MEMS chip for in situ TEM heating experiments

Abstract

In situ transmission electron microscopy (TEM) is a powerful tool for advanced material characterization. It allows real-time observation of structural evolution at the atomic level while applying different stimuli such as heat. However, the validity of analysis strongly depends on the quality of the specimen, which has to be prepared by thinning the bulk material to electron transparency while maintaining the pristine properties. To address this challenge, a novel method of TEM samples preparation in plan-view geometry was elaborated based on the combination of the wedge polishing technique and an enhanced focused ion beam (FIB) workflow. It involves primary mechanical thinning of a broad sample area from the backside followed by FIB-assisted installation on the MEMS-based sample carrier. The complete step-by-step guide is provided, and the method’s concept is discussed in detail making it easy to follow and adapt for diverse equipment. The presented approach opens the world of in situ TEM heating experiments for a vast variety of fragile materials. The principle and significant advantage of the proposed method are demonstrated by new insights into the stability and thermal-induced strain relaxation of Ge Stranski–Krastanov islands on Si during in situ TEM heating. Graphical abstract

Unraveling the mechanism of vanadium self-intercalation in 1T-VSe2: atomic-scale evidence for phase transition and superstructure model for intercalation compound

“…Bulk VSe 2 single crystals (mm size) were grown by chemical vapor transport (CVT) following a previous report [47]. TEM sample were prepared using the conventional FIB 'lift-out' method using a Thermofisher Helios G4 dual-beam system [48]. At first, a capping layer (consisting of ∼40 nm amorphous carbon films, ∼100 nm Pt film, and ∼2 µm Pt film) was deposited onto the sample's region of interest by focused electron and/or ion beam induced deposition.…”

In Situ Study of the Interface-Mediated Solid-State Reactions during Growth and Postgrowth Annealing of Pd/a-Ge Bilayers

“…Obtaining nanoscale information about metastable structures is extremely challenging. The low energy required for the interface reaction complicates the interpretation of high-resolution transmission electron microscopy results commonly used to study buried interfaces, facilitating intermixing, compound formation, amorphization, and selective sputtering during sample preparation and electron irradiation. − Noninvasive real-time methods can overcome this problem. Furthermore, they provide real-time access to the evolving structures.…”

Enhanced Preparation Technique of Plan-view Specimens for in situ TEM Heating Experiments based on the Synergy of Wedge-polishing and FIB

“…To highlight the inherent strain of the SK islands the two-beam condition (TBC) has been utilized. Major strain relaxation in the islands occurs through the formation of stacking faults at 625°C induced by the different thermal expansion coefficients of the inherent materials [3]. These findings can be barely achieved without applying the elaborated method that, in particular, proves its conceptual advancement for semiconductor materials research.…”

“…These findings can be barely achieved without applying the elaborated method that, in particular, proves its conceptual advancement for semiconductor materials research. We provide the complete step-by-step guide and discuss the method's concept in detail making it easy to follow and adapt for diverse equipment [3,4].…”

“…To make a step in solving this challenge we elaborate a novel method for sample preparation, which opens the world of in situ TEM heating experiments for a vast variety of fragile materials ranging from MBEgrown semiconductor nanolayers [3] to industrial coatings. It involves primary mechanical thinning of a broad sample area from the backside followed by FIB-assisted installation on the MEMS-based sample carrier (Figure 1).…”