Size and composition dependent electronic and optical properties of GaxAl1−xAs and AlxGa1−xAs alloyed nanocrystals

Abstract

By using density-functional tight-binding method, we have shown the size and composition dependent variation of band gap and excitation spectra of both GaxAl1−xAs and AlxGa1−xAs alloyed semiconductor nanocrystals. The two systems differ with respect to the surface atoms, while in one case the surface atoms are Ga, while in another case it is Al, and hence the effect of structural relaxations in GaxAl1−xAs and AlxGa1−xAs are different leading to different final structures and properties. We observed a bowing effect in the band gap values as it is experimentally found in many semiconductor alloys.