Strain relaxation in In0.2Ga0.8As/GaAs quantum-well structures by x-ray diffraction and photoluminescence

Abstract

The onset of strain relaxation in In 0.2 Ga 0.8 As/GaAs quantum-well structures is investigated. X-ray diffraction shows that when the InGaAs thickness increases beyond its critical thickness, another peak on the right shoulder of the GaAs peak appears, indicating that the top GaAs layer is being compressed in the growth direction by the relaxation of the InGaAs layer. Energy shifts of 44 and 49 meV are observed, respectively, from the strains of the InGaAs and GaAs top layers when increasing the InGaAs thickness from 300 and 1000 Å. These energy shifts are in agreement with theory calculated based on the relaxation process observed in x-ray diffraction, providing evidence that the relaxation occurs from near the bottom InGaAs/GaAs interface while the top interface still remains strained. This result is further corroborated by the images of cross-sectional transmission electron micrographs which show that most of the misfit dislocations are confined near the bottom interface.

Critical thickness of MBE-grown Ga1−xInxSb (x<0.2) on GaSb

“…al. [10] found that this is also the point when the PL from the material starts deteriorating. As applications for this material system is mostly light emitters, the error made in setting t c at the thickness where it can be detected by XRD should not affect its usefulness.…”

“…Selvig et al [9] and Chen et al [10] have found that the fringes disappear after the onset of relaxation. For the determination of relaxation, scan (a) would be considered to arise from unrelaxed GaInSb, whereas (c) would be considered to be from partially relaxed GaInSb.…”

Emission and HR-XRD study in InAs quantum dot structures prepared at different QD’s growth temperatures

“…InGaAs/GaAs quantum wells (QWs) with InAs quantum dots (QDs) have been the subject of great interest due to the variety of applications, such as: semiconductor lasers for the optical fiber communication [1][2][3], infrared photo-detectors [4][5][6] and electronic memory devices [7,8]. Extensive efforts have been applied during the last two decades for the manipulation and control the position, size, shape and density of QDs, as well as a number of stacking QD layers for the high efficient devices [9][10][11][12].…”

Raman and AFM studies of swift heavy ion irradiated InGaAs/GaAs heterostructures

“…An enormous amount of work has been reported on the characterization of strain and the strain relaxation mechanisms of heterostructures grown beyond the critical layer thickness. The most suitable and well established techniques for such studies are high resolution XRD (HRXRD) [3][4][5], ion channelling [6,7], electron microscopy [8,9] and Raman spectroscopy [10][11][12][13]. Since the lattice dynamics are affected by stress-induced lattice deformation, the strain in epitaxial layers and its relaxation can be analysed through the evaluation of the phonon frequencies in the Raman spectrum.…”