Synchrotron X‐ray Renninger scanning for studying strain in InAs/GaAs quantum dot system

Abstract

A systematic procedure for ultra‐precise lattice parameter determination using X‐ray Renninger scanning (XRS) is optimized and applied to probe the average in‐plane strain in series of samples representing the different stages of the growth process of single‐buried quantum dots (QDs). Covering InAs QDs growth on GaAs(001) substrates generates an expansive in‐plane strain that is related to the density of QDs. Rocking curves and atomic force microscopy are also used for a general qualitative analysis of the growths, as well as of the morphology and density of the QDs. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

X-ray dynamical diffraction in amino acid crystals: a step towards improving structural resolution of biological moleculesviaphysical phase measurements

“…Wide azimuthal scans are possible, although eventual corrections of the incidence angle are necessary depending on the residual misalignment between the diffraction vector and the rotation axis. This procedure is preferred in terms of accuracy in both line profile and position of the peaks (Freitas et al, 2007), although after fixing the sample one is limited to reflections that can be aligned within the AE20 range of the adjustment arcs. The rotating crystal method for indexing and pre-alignment of accessible reflections has been used, as demonstrated in xA1.…”

Growth and capping of InAs/GaAs quantum dots investigated by x-ray Bragg-surface diffraction

“…For each deposition rate two samples were prepared: one without capping and another with a 30 nm GaAs cap layer grown at the same substrate temperature of 510°C. In the samples with no cap layer, densities of 177 QDs/ m 2 and 360 QDs/ m 2 were observed via atomic force microscopy, 21 which implies in an average volume of InAs material per QD of 4.4ϫ 10 3 and 2.1ϫ 10 3 nm 3 , for the low ͑0.007 ML/s͒ and high ͑0.09 ML/s͒ deposition rates, respectively. The monolayer thickness of strained InAs considered when calculating these volumes was 0.325 nm.…”

Распределение Интенсивности Трехволновой Дифракции От Дислокационных Эпитаксиальных Слоев В Обратном Пространстве

“…В основном, ее применение ограничивалось определением параметров решетки и деформаций в них [1][2][3]. Лишь в последние годы появились работы, касающиеся влияния структурных дефектов (в основ-ном, дислокаций) на поведение картины трехволной дифракции, измеренной по схеме Реннингера [4][5][6][7][8][9].…”