TIGHT-BINDING CALCULATION - ELECTRONIC-STRUCTURE OF (BESE)(N) (SI-2)(M) SUPERLATTICES/

In a semiempirical sp(3)s tight-binding scheme, bulk parameters for B eSe are determined by fitting the first-principles calculation and the detailed calculations of electronic structure of the (BeSe)(n)/(Si-2) (m) (110) superlattices are performed within a Nide range of n,m less than or equal to 20. It is found that the fundamental energy gap incre ases (up to 2.11 eV at the (X) over tilde point for n=m=2) with decrea sing superlattice period and the Si layer plays an important role in d etermining the fundamental energy gap of the superlattice system due t o spatial quantum confinement effects. For air reasonable values (rang ing from a to 3.5 eV) of the valence-band discontinuity used in the ca lculation, there is an empty interface band in the thermal gap of the (BeSe)(n)/(Si-2)(m) (110) (n, m less than or equal to 20) system and t he conduction band minima shift from X to Gamma along <(Gamma X)over b ar> while increasing the band offset; but they never reach the Gamma p oint.