An optimized TEM specimen preparation method of quantum nanostructures

TL;DR

This paper presents an optimized method for preparing high-quality TEM specimens of quantum nanostructures, specifically SrRuO3 quantum dots on SrTiO3, improving microstructure preservation and reducing damage.

Contribution

The study introduces a novel combination of ion-beam-milling techniques with focused ion-beam imaging for better TEM specimen preparation of quantum nanostructures.

Findings

Higher-quality TEM specimens achieved compared to traditional methods.

Simultaneous imaging ensures accurate positioning of quantum dots.

Preparation of large, separated electron-transparent regions reduces specimen bending.

Abstract

Electron transparent TEM lamella with unaltered microstructure and chemistry is the prerequisite for successful TEM explorations. Currently, TEM specimen preparation of quantum nanostructures, such as quantum dots (QDs), remains a challenge. In this work, we optimize the sample-preparation routine for achieving high-quality TEM specimens consisting of SrRuO3 (SRO) QDs grown on SrTiO3 (STO) substrates. We demonstrate that a combination of ion-beam-milling techniques can produce higher-quality specimens of quantum nanostructures compared to TEM specimens prepared by a combination of tripod polishing followed by Ar+ ion milling. In the proposed method, simultaneous imaging in a focused ion-beam device enables accurate positioning of the QD regions and assures the presence of dots in the thin lamella by cutting the sample inclined by 5{\deg} relative to the dots array. Furthermore, the preparation of TEM lamellae with several large electron-transparent regions that are separated by thicker walls effectively reduces the bending of the specimen and offers broad thin areas. The final use of a NanoMill efficiently removes the amorphous layer without introducing any additional damage.