High-resolution X-ray characterization of mid-IR Al_0.45Ga_0.55As/GaAs Quantum Cascade Laser structures

In this paper, the X-ray diffraction profiles of Quantum Cascade Laser (QCL) structures have been investigated. The examined structures were grown by molecular beam epitaxy. The crystallographic characterization was carried out using high resolution X-ray diffractometer. The information about thickness of individual layers and periodicity of the structures was derived from simulation of diffraction profiles calculated using dynamical diffraction theory. The influence of interface roughness on the shape of satellite peaks was studied. The particular attention has been paid to the analysis of the broadening of satellite peaks. The presented results show that broadening is due to the variation of thickness of individual layers. - Highlights: • Crystallization of four complete AlGaAs/GaAs Quantum Cascade Laser (QCL) structures • The non-abrupt interfaces have no influence on the shape of satellite peaks. • The broadening of the satellite peaks is caused by changes of period thickness. • Crystallization of good quality of three complete QCL structures