Accession Number : ADA372481


Title :   Atomistic and Ab Initio Calculations or Ternary II-IV-V2 Semiconductors


Descriptive Note : Final technical rept. 1 Aug 96-31 Jul 99


Corporate Author : MICHIGAN TECHNOLOGICAL UNIV HOUGHTON DEPT OF PHYSICS


Personal Author(s) : Pandey, Ravi


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a372481.pdf


Report Date : 07 Dec 1999


Pagination or Media Count : 61


Abstract : Atomistic and ab initio methods are used to study structural and electronic properties of perfect and defective chalcopyrites, specifically, ZnGeP2 and CdGeAs2. These materials are important due to their suitability for nonlinear optical applications in the infrared region and have a wide transparency region. A new set of interatomic potential parameters consisting of two- and three-body terms is developed reproducing crystal lattice constants, elastic and dielectric constants very well. The calculated formation energies for native defects suggest that the intrinsic disorder is dominated by antisites in the cation sublattice followed by the Schottky and Frenkel defects. Although both compounds belong to the same chalcopyrite family, the nature of dominant acceptors is predicted to be different. Defect calculations corroborating the experimental studies find that the zinc vacancy, not the zinc antisite (ZnGe), is associated with the dominant acceptor center in ZnGeP2. This is not the case in CdGeAs2 where a cadmium antisite (CdGe) is predicted to be associated with the dominant acceptor in the lattice. This difference may well be due to defect-induced lattice distortion which plays a key role in stabilizing the hole states in the lattice.


Descriptors :   *OPTICAL MATERIALS , *SEMICONDUCTORS , *TERNARY COMPOUNDS , *CADMIUM COMPOUNDS , *ZINC COMPOUNDS , QUANTUM CHEMISTRY , CRYSTAL LATTICES , ELASTIC PROPERTIES , ORDER DISORDER TRANSFORMATIONS , HOLES(ELECTRON DEFICIENCIES) , NONLINEAR OPTICS , ATOMIC ORBITALS , DIELECTRIC PROPERTIES , DEFECTS(MATERIALS) , MOLECULAR STRUCTURE , VACANCIES(CRYSTAL DEFECTS) , ELECTRON ACCEPTORS , INFRARED SPECTRA


Subject Categories : Inorganic Chemistry
      Atomic and Molecular Physics and Spectroscopy
      Optics


Distribution Statement : APPROVED FOR PUBLIC RELEASE