Resonant coherent Bragg rod analysis of strained epitaxial heterostructures

Abstract

The resonant response of the complex x-ray scattering factor has been used in conjunction with the coherent Bragg rod analysis phase-retrieval algorithm to determine the composition and strain profiles of ultrathin layers of GaAs grown on InGaAs buffers. The buffer layers are nominally latticed matched with the InP substrate and the subsequent GaAs growth is compared at two different temperatures: 480 and 520°C. We show that electron density maps extracted from Bragg rod scans measured close to the Ga and As K-edges can be used to deconvolute roughness and intermixing. It is found that indium incorporation and roughening lead to a significant reduction of the strain in this system.

Correlating structure, strain, and morphology of self-assembled InAs quantum dots on GaAs

“…The energies were selected to enhance chemical sensitivity, by exploiting the energy dependence of the scattering factors of the constituent elements of the system. 10 Our results reveal key aspects of the microscopic structure and morphology that may have an important bearing on their optoelectronic properties. In particular, we present direct structural evidence supporting previous photoluminescence-based claims that the wetting layer is largely consumed by the QDs at high coverage.…”

Anisotropic electronic properties of a-axis-oriented Sr2IrO4 epitaxial thin-films

“…Since it is not clear how the artificial ab-plane anisotropy, i.e., strain-induced, different a-and b-axes lattice parameters, distorts the IrO 6 octahedra in a-axis-oriented thin films, microscopic characterizations such as scanning transmission electron microscopy 21,22 and resonant X-ray diffraction 23,24 will provide additional important information.…”

High‐Resolution Crystal Truncation Rod Scattering: Application to Ultrathin Layers and Buried Interfaces

“…The initial application of the COBRA algorithm by Yacoby and co‐workers [ 79 ] pertained to the AlAs/GaAs (001) interface, and several early applications focused on other III‐V heterointerfaces, including InAs/GaSb (001) [ 154 ] and GaAs/InGaAs/InP (001). [ 155 ] Moreover, CTR scattering has been extensively used to study the structure and composition of III–V nanostructures and quantum dots. [ 156,157 ] From COBRA analysis, the composition profile as well as the shape of dots could be extracted, providing important insights into dot formation and interdiffusion.…”