Pseudopotential-based multiband {bold k{center_dot}p} method for {bold {approximately}}250000-atom nanostructure systems
- National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)
The electronic structure of quantum wells, wires, and dots is conventionally described by the envelope-function eight-band {bold k{center_dot}p} method (``the standard {bold k{center_dot}p} model``) whereby coupling with bands other than the highest valence and lowest conduction bands is neglected. There is now accumulated evidence that coupling with other bands and a correct description of far-from-{Gamma} bulk states is crucial for quantitative modeling of nanostructure. While multiband generalization of the {bold k{center_dot}p} exists for {ital bulk} solids, such approaches for {ital nanostructures} are rare. Starting with a pseudopotential plane-wave representation, we develop an efficient method for electronic-structure calculations of nanostructures in which (i) multiband coupling is included throughout the Brillouin zone and (ii) the underlying bulk band structure is described correctly even for far-from-{Gamma} states. A previously neglected interband overlap matrix now appears in the {bold k{center_dot}p} formalism, permitting correct intervalley couplings. The method can be applied either using self-consistent potentials taken from {ital ab} {ital initio} calculations on prototype {ital small} systems or from the empirical pseudopotential method. Application to both short- and long-period (GaAs){sub {ital p}}/(AlAs){sub {ital p}} superlattices (SL) recovers (i) the bending down (``deconfinement``) of the {bar {Gamma}}({Gamma}) energy level of (001) SL at small periods {ital p}; (ii) the type-II{endash}type-I crossover at {ital p}{approx_equal}8 SL, and (iii) the even-odd oscillation of the energies of the {ital {bar R}}/{ital {bar X}}({ital L}) state of (001) SL and {bar {Gamma}}({ital L}) state of (111) SL. Introducing a few justified approximations, this method can be used to calculate the eigenstates of physical interest for large nanostructures.
- OSTI ID:
- 392137
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 54, Issue 16; Other Information: PBD: Oct 1996
- Country of Publication:
- United States
- Language:
- English
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