Strain in buried quantum wires: Analytical calculations and x-ray diffraction study

Abstract

The displacement field in and around periodically arranged quantum wires embedded in a crystalline matrix is calculated analytically for an arbitrary finite thickness of the cover layer. A good agreement is obtained between measured x-ray-diffraction peaks of a wire structure and kinematical calculations with the displacement field derived in the paper. The strain and quantum size effects on the photoluminescence line shift are found to be comparable, due to small width ͑35 nm͒ of the wires.

Magnetic analysis of MnAs films grown on GaAs and Si substrates for potential spintronics and magnetocaloric applications

“…On the contrary the MnAs/SiO 2 /Si films are polycrystalline with random oriented a-MnAs grains. In all the samples the paramagnetic b-phase was not detected at 300 K, in agreement with other works on MOVPE-grown MnAs/(0 0 1)GaAs films [11] but in contrast with the results of Kaganer et al [9] on MBE-grown MnAs/ (0 0 1)GaAs films. However, we cannot exclude the possible occurrence of phase coexistence in the temperature region above 300 K where we have found the transition to occur (see below).…”

“…In the case of MBE grown MnAs/(0 0 1)GaAs epitaxial films, a two-phase coexistence region between a-and b-MnAs phases has been reported to occur in the temperature interval around T c [8]. This fact involves a separation of the film into ferromagnetic and paramagnetic stripe domains oriented along the c-axis [9]. It should be noted that when MnAs films are deposited on (0 0 1)GaAs, a-phase layers can be stabilized with two variants, A-type and B-type, depending on the epitaxial growth direction [10], although only single phase bMnAs with a B-type variant has been previously stabilized in MOVPE films [11,12].…”

X-ray scattering: A powerful probe of lattice strain in materials with small dimensions

“…Thus, in well-ordered structures X-ray diffraction may yield a very detailed information about strain fields at the nanometer scale. A number of studies have been performed on single crystal structures fabricated from semiconducting materials [21,23,27,28]. Because the information on the phase of the scattered field is lost, it is not possible to extract directly the displacement field from the measured intensity.…”

The semi-transparent diamond monochromator at the ESRF Troika beamlines

“…2,3 The beam transmitted through the diamond crystal impinges on a second monochromator located ~44 m downstream the source in the ID10A experimental hutch. This station is dedicated to high resolution WAXS and slow dynamics studies by means of photon correlation spectroscopy with coherent X-rays (XPCS).…”