Elementary energy bands in the band structure of A(IV), A(III)B(V) crystals and superlattices built upon them

摘要

A concept of the elementary energy bands was applied to interpret the electronic energy spectra of crystals from the cubic system and the superlattices (GaAs)(M)/(AlAs)(M) (M = 5, 10), (Si)(10)/(Ge)(10) built upon them. Based upon this example, it was shown that the elementary energy bands concept elaborated in the empty-lattice approximation allows one to predict the symmetry and topology of the valence band of artificial periodic systems as well as the spatial valence-electron density distribution in a unit cell of those systems. A verification of this conclusion was confirmed by the ab-initio band-structure calculations of the superlattices mentioned above. An energy-structural factor was found that joins two elementary energy bands characteristic for T-d(2) symmetry crystals into a physical complex that is related to the elementary energy band of the O-h(7) symmetry crystals. This relationship between the elementary energy bands was utilized to find the actual Wyckoff position in the superlattice's unit cell responsible for the spatial electron density distribution. (C) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.