X-ray scattering from self-assembled InAs islands

Abstract

In this work several structural and chemical properties of self-assembled InAs islands grown on GaAs(001) are studied using surface x-ray scattering with synchrotron radiation. The technique of x-ray diffraction under grazing incidence condition was employed to differentiate coherent and incoherent islands. We used a model of a strained pyramidal island to interpret the x-ray results and correlate size and strain-state of these islands. The degree of GaAs interdiffusion in the islands was inferred from the variation of volume of the unit cell. The Poisson's ratio of the two materials involved establishes a limit of tetragonal distortion for this material. Any variation in this distortion is associated with the presence of Ga inside the islands.

Resonant X-ray diffraction of self-assembled epitaxial systems: From direct to complementary chemical information

“…4(b) can be employed to draw a twodimensional projection map of in-plane local lattice parameter a = a SnTe h/2 (considering |h| = |k|) -for EuTe islands. In such iso-strain projections the areas with each lattice parameter are drawn following the simple ellipse constraint (x 2 + y 2 /L 2 ) ≤ 1, where x,y and L are the coordinates and iso-lattice parameter lateral size along the [1][2][3][4][5][6][7][8][9][10] and [2,11] directions, here considered the same accordingly to the equal L sizes obtained from measurements in the 220 family of reflections [23]. Figure 4(c) shows the in-plane iso-lattice parameter projections for dots.…”

“…However, little is known about ternary IV-VI magnetic QDs as well as for quaternary III-V systems. Resonant X-ray Diffraction (RXD) [10][11][12][13][14] in grazing incidence geometry (GID) has indicated, along with Electron Energy Loss Spectroscopy (EELS) [15], that none of these QDs are free from substrate atoms. A probe that determines simultaneously the concentration of each element inside the QDs as well as the strain they are submitted is thus necessary to better understand the influence of growth parameters on the final characteristics of the islands.…”

Development and functional assessment of natural latex membranes : a new proposal for the treatment of amblyopia

“…The scattering patterns in Figure 5.3 show a peak at 2= 18.9°, which corresponds to q=1,34 Å -1 . This value is equal to a repetition distance of approximately 4.69 Å, which is compatible with the size of the isoprene monomer (Malachias et al, 2004, Schmacke, 2010.…”