Critical layer thickness and strain relaxation measurements in GaSb(001)/AlSb structures

Measurements of critical layer thicknesses and strain relaxation have been made for AlSb single layers and GaSb/AlSb superlattices on GaSb(001) using ion scattering/particle-induced x-ray techniques, x-ray diffraction, and Raman scattering. The ion beam techniques and x-ray diffraction indicate a critical thickness on the order of 100-170 Å. Raman scattering from superlattice samples using 5145 Å excitation shows the most rapid strain relaxation versus layer thickness and indicates a lower apparent critical thickness on the order of 50-100 Å. The influence of the finite experimental resolution is addressed. The experimental critical thickness and the strain relief are compared to theoretical models. The equilibrium critical thickness of these models is consistent with the experimental value, indicating that metastable strain retention is not a dominant process in the GaSb(100)/AlSb system under the present growth conditions.