Structure and optical properties of a composite AsSb–Al$_{0.6}$Ga$_{0.4}$As$_{0.97}$Sb$_{0.03}$ metamaterial

Epitaxial layers of Al$_x$Ga$_{1-x}$As$_{1-y}$Sb$_y$ with an aluminum content $x\sim$ 60% and antimony content $y\sim$3% were successfully grown by molecular-beam epitaxy at low temperature. A developed system of AsSb nanoinclusions was formed in the semiconductor matrix by subsequent annealing. The extended transparency window of the obtained metamaterial allows us to document the absorption of light near the interband absorption edge of the Al$_x$Ga$_{1-x}$As$_{1-y}$Sb$_y$ semiconductor matrix. Parameters of the observed extinction band allow us to attribute the optical absorption to the plasmon resonance in the system of AsSb nanoinclusions.