The band structure of the(InAs)i(GaAs)i strained superlattice is calculated by the self-consistent pseudopotential method.The results show that the(InAs)_(1)(GaAs)_(1) is a direct-gap superlattice.With the local density approximation,the band gap calculated with the room-temperature lattice constants is 0.43eV,and the corrected value is 0.91 eV,in agreement with experimental results.Because of the lattice mismatch between InAs and GaAs layers,the three-fold degenerate energy level at the top of valence band splits into two levels with a spacing of 0.29 eV.The splitting of energy level is also estimated and explained using the effective-mass theory.
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