Atomically Defined Rare‐Earth Scandate Crystal Surfaces

Abstract

The fabrication of well‐defined, atomically sharp substrate surfaces over a wide range of lattice parameters is reported, which is crucial for atomically regulated epitaxial growth of complex oxide heterostructures. By applying a framework for controlled selective wet etching of complex oxides on the stable rare‐earth scandates (REScO3), apseudocubic = 0.394 – 0.404 nm, the large chemical sensitivity of REScO3 to basic solutions is exploited, which results in reproducible, single‐terminated surfaces. Time‐of‐flight mass‐spectroscopy measurements show that after wet etching the surfaces are predominantly ScO2 ‐terminated. Moreover, the morphology study of SrRuO3 thin‐film growth gives no evidence for mixed termination. Therefore, it is concluded that the REScO3 surfaces are completely ScO2 ‐terminated.

Super switching and control of in-plane ferroelectric nanodomains in strained thin films

“…GmbH) by pulsed laser deposition using a pulsed KrF excimer laser (l ¼ 248 nm), from Pb x Sr 1 À x TiO 3 targets with 4 atomic % excess lead. The substrates were treated to get a single ScO 2 termination 33,46 , allowing the growth of high-quality SrRuO 3 bottom electrodes. The growth was followed in situ by reflection highenergy electron diffraction and the films thickness was determined from the reflection high-energy electron diffraction intensity oscillations, together with X-ray reflectivity.…”

Reconstructions at complex oxide interfaces

“…The measurements were performed at room temperature to 150 • C. Note that DyScO 3 has no structural phase transition in this temperature range, as mentioned in SrRuO 3 growth: Using specific growth conditions, the nucleation and growth of SrRuO 3 is very sensitive to the atomic composition of the surface. [14,44] SrRuO 3 was grown using pulsed laser deposition (PLD) at a pressure of 0.3 mbar, 50%-50% O 2 -Ar. The substrate temperature was approximately 600-640 • C. SrRuO 3 was deposited with a repetition rate of 1 Hz and a fluence of 2.1 J cm −2 , using a KrF laser (λ = 248 nm).…”

“…2.11b), which is due to the mixed termination of the DyScO 3 surface prior to growth. [14,44] One hour selective etching was not sufficient to remove all Dy ions of the surface. Note that the minimum required selective etching time varied from sample to sample and, therefore, the surface roughening step is introduced.…”

“…Therefore, SrRuO 3 was grown on DyScO 3 by PLD to verify single or mixed termination of the DyScO 3 surface. [14] Figure 2.11 shows the surface morphology after SrRuO 3 growth on DyScO 3 , with and without the additional surface roughening step, measured in situ by non-contact AFM. The samples treated with the additional surface roughening step show the typical morphology of a flat SrRuO 3 film grown in a mixed step-flow and layer-by-layer growth mode, as shown in Figure 2.11a.…”

“…As mentioned before, exchanging this order gives another difficulty: Dy diffusion to the surface during high temperature annealing, resulting in mixed termination. [14,33] Therefore, an additional etching step after annealing is introduced, which roughens the topmost layer at the nanometer scale (see Fig. 2.8b).…”