Relaxation and tilting of single and double layer structures of AlGaSb/GaSb-LPE studied by high resolution x-ray diffraction

Abstract

Epitaxial AlGaSb double-layer structures grown on GaSb (001) substrates by Liquid Phase Epitaxy (LPE) were analyzed by high-resolution x-ray diffraction (HRXRD). Four AlGaSb double-layer structures grown at 450 °C were analyzed varying the thickness of the first layer and maintaining the same thickness for a second layer growth. Symmetric reciprocal space mapping measurements around the (004) reflection and asymmetric rocking curves around the (115) reflections have revealed that a subsequent Al0.15Ga0.985Sb growth on an Al0.047Ga0.953Sb layer modifies the relaxation and lattice tilting of the first layer. This behavior is attributed to the formation of dislocations within the layers during the growth and transported between them. In this work, the study was realized ex situ and is in well agreement with in situ studies and theoretical predictions on the relaxation of epitaxial films in diverse materials. The structural analysis of lattice distortion in epitaxial layers is relevant since it could modify the electrical behavior of optoelectronic devices building with them.

Keywords

• AlGaSb
• relaxation
• tilting
• epitaxial structure
• high resolution x-ray diffraction
• reciprocal space mapping