Quasi-ideal strontium titanate crystal surfaces through formation of strontium hydroxide

Abstract

In recent years, well-defined and nearly perfect single crystal surfaces of oxide perovskites have become increasingly important. A single terminated surface is a prerequisite for reproducible thin film growth and fundamental growth studies. In this work, atomic and lateral force microscopy have been used to display different terminations of SrTiO3. We observe hydroxylation of the topmost SrO layer after immersion of SrTiO3 in water, which is used to enhance the etch-selectivity of SrO relative to TiO2 in a buffered HF solution. We reproducibly obtain perfect and single terminated surfaces, irrespective of the initial state of polished surfaces and the pH value of the HF solution. This approach to the problem might be used for a variety of multi-component oxide single crystals. True two-dimensional reflection high-energy electron diffraction intensity oscillations are observed during homo epitaxial growth using pulsed laser deposition on these surfaces.

Monodomain strained ferroelectricPbTiO3thin films: Phase transition and critical thickness study

“…The substrate-surface treatment followed the procedure outlined by Koster et al 24 The PTO thin films were grown at 570°C using reflection high-energy electron diffraction assisted pulsed-laser deposition ͑KrF excimer laser of = 248 nm͒. A laser spot size of 2.5 mm 2 with an energy density of 2 J / cm 2 at an oxygen background pressure of 0.13 mbar was used, and the substrate-target distance was kept between 48 and 51 mm.…”

Electronic Reconstruction at the Interface Between Band Insulating Oxides: The LaAlO3/SrTiO3 System

“…Kawasaki et al [24] and later-on Koster et al [25] used a combination of chemical etching and oxygen post annealing to realize perfectly single-terminated STO (001) substrates [ Fig.2c]. Later studies demonstrated that these single crystals were TiO 2 -terminated and structurally unreconstructed [26]; this is at odds with several previous surface studies on ultra high vacuum (UHV) prepared STO single crystals, which exhibited a wide range of reconstructions, like 2x1, 2x2, c2x2 and √5x √5-R26.6° [27], depending essentially on the annealing temperatures in UHV…”

Воздействие механических напряжений на зарядовое состояние межфазной границы в гетероструктурах LaAlO-=SUB=-3-=/SUB=-/(001)SrTiO-=SUB=-3-=/SUB=- c нарушенной стехиометрией

“…Каналовые спектры MEIS, полученные для гетероструктур LAO/STO с толщиной слоя LAO в 1 и 3 u. c., показаны на рис. Отметим, что блочный характер структуры подложки STO, неоднородные механические напряжения, наличие на свободной поверхности титаната стронция участков, покрытых двухслойными пакетами TiO 2 [6] и карбонатом стронция (SrCO 3 [7]), могут влиять на интенсивность катионных замещений в области межфазной границы между слоем LAO и подложкой STO и, как следствие, глубина проникновения атомов лантана в подложку на различных участках последней не является одинаковой, а латерально варьируется.…”