Electronic Properties and Stability of Artificial In-N Molecules
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Electronic Properties and Stability of Artificial In-N Molecules Liudmila A Pozhar1 and William C Mitchel2 1 the Center for Materials for Information Technology, University of Alabama, P.O. Box 870209, Tuscaloosa, AL, 35487-0209 2 Materials and Manufacturing Directorate, Air Force Research Laboratory, 3005 Hobson Way, Bldg.651, Wright-Patterson AFB, OH, 45433-7707
ABSTRACT In the work reported here the Hartree-Fock (HF), restricted open shell HF (ROHF), and multiconfiguration self-consistent field (CI/CASSCF/MCSCF) methods are used to predict electronic properties of several artificial molecules of InAsN and indium nitride whose structure and composition have been derived from those of the corresponding symmetry elements of the zincblende and wurtzite bulk lattices. Both quantum-confined and “vacuum” clusters (whose geometry has been optimized without any spatial constraints applied to the atomic positions) were studied focusing on the electronic energy level structure, direct optical transition energy (OTE), and charge and spin distributions. The obtained results indicate that inclusion of “impurity” atoms (such as As atoms) may enhance stability of both vacuum and confined pyramidal In-N molecules and provide for manipulations of the OTE in a wide range of its values. The CI/CASSCF/MCSCF OTEs of the studied wurtzite-based clusters may also vary in a wide range, from 1.7440 eV for the smallest pre-designed prismatic molecule In6N6 to 6.9780 eV for its almost perfect prismatic “vacuum” counterpart. These evaluations closely correlate with experimental data available in literature. INTRODUCTION Despite numerous experimental and theoretical studies, information on basic electronic properties, such as the band gap values, of In-N nanostructures remains inconclusive. Moreover, an impact of quantum confinement on electronic properties of small indium nitride clusters has to be analyzed from the first principles. Such studies are very important for the development of integrated circuits (ICs) where the density of elements is orders of magnitude higher than that of existing ICs. Correspondingly, 3D nanoheterostructures, such as those composed of quantum dots and wires synthesized in the confinement provided by porous membranes with wellcharacterized arrays of nanopores of a few nanometers in diameter, are needed to ensure the high IC performance required to implement intensive computations and imaging [1]. The structure units of such materials may be based on small In-N and other semiconductor compound artificial molecules, synthesized in and stabilized by quantum confinement. Other important applications of such materials include the development of a variety of high power electronic device applications, in particular efficient solar cells, tunable light emitting diodes and sensors. While studies of small confined artificial molecules composed of a few semiconductor compound atoms are almost beyond resolution of contemporary experimental methods, such
molecules can be synthesized by fundamental theory-based
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