PALS and ab initio/DFT calculations on Zn-based nanostructured semiconductors

GERMÁN N. DARRIBA; MARCOS MEYER; MARIO RENTERÍA; LAURA C. DAMONTE

Brasov

Conferencia; HYPERFINE 2021 - 3rd International Conference on Hyperfine Interactions and their Applications; 2021

HFI Executive Committee

Positron Annihilation Lifetime Spectroscopy (PALS) and all-electron electronic structure calculations from first-principles were combined to investigate structural and electronic properties on Zn-based II-VI semiconductors. ZnT (T:O, Se and Te) pure and Al-doped nanopowders were obtained by mechanical milling at increasing milling times. The progressive substitutional incorporation of Al atoms into the Zn-based semiconductor structure was monitored by PALS measurements, identifying also the defects induced by mechanical work. Additionally, combining two first-principles methods based on the Density Functional Theory (DFT) we calculated the final equilibrium structures for different concentrations of Al doping and Zn vacancies in these nanopowder semiconductors, predicting afterwards the characteristic positron annihilation lifetimes at these equilibrium structures. This experimental and ab initio/DFT combined study allows us to verify the dopant incorporation into the Zn-based pure crystalline structures and to characterize the mechanical induced defects. Finally, with the aim to elucidate electronic modifications distortions introduced by the different defects (Al substitutional, Zn vacancies) in the semiconductor matrix, the different densities of electronic states (DOS) were evaluated confirming the semiconductor character of all samples. The joint experimental and theoretical analysis will allow us to achieve a better comprehension on the structural and optical properties of these semiconductors towards their potential applications.