Composition manipulation of near infrared InAsxSb1−x nanocrystals: Atomistic tight-binding theory

Abstract

Based on a successful atomistic tight-binding model in the conjunction with an empirical bowing parameter and the widely used virtual crystal approximation, the theoretical investigations of near infrared InAsxSb1−x nanocrystals with the experimentally synthesized sizes and As compositions (x) are reported. Under various experimental As compositions (x), the single-particle spectra, charge densities, density of states (DOS), overlaps of ground electron and hole wave functions, optical spectra, atomistic electron-hole interactions and stokes shift are numerically computed. I report the correlation of the structural and optical properties of InAsxSb1−x nanocrystals with different alloy compositions (x). With the increasing compositions (x), the single-electron energies are increased, while the single-hole energies are reduced, thus introducing the wider optical band gaps. The atomistic tight-binding model reproduces very well the change in the band gap values with the compositions observed in the experimental reports. The As compositions (x) of alloy InAsxSb1−x nanocrystals are used to propel photonic and optoelectronic device performance in a broad range of the near infrared spectrum with the wave length from 825 to 990 nm. With the increasing content (x), the optical intensities are reduced, whereas atomistic electron-hole interactions and stokes shift are progressively increased. Finally, the present systematic study of alloy InAsxSb1−x nanocrystals is one of the most important milestones on the road to provide the understanding of the composition-dependent structural and optical properties and a complete tactic to design a facile band gap modulation method of preparing the interesting near infrared emitting devices and detectors.