Tight-binding calculations of energy gaps in (001)-(InAs)(n)(InSb)(m) strained superlattices

Tight-binding calculations of electronic structures for (001)-(InAs)(n)(InS b)(m) strained layer superlattices are presented. The dependences of the su perlattice band gap on the band offsets between InAs and InSb are examined for three different types of biaxial strains. It is found that the band gap depends strongly on the band offset, and that for m=1 the ordering lowers the band gap with respect to the random alloy. A comparison with the photol uminescence data for the energy gaps of (nx1) strained-layer superlattices is discussed. In addition, the electronic structures of strained InAs quant um wells are calculated, and interpretations are provided for the observed type-I to type-II band alignment transition at n=5 in a quantum well formed by (nx1) strained layer superlattices and AlSb barriers. Changes of energy gaps with layer thicknesses in strained layer superlattices with n=m and n =8-m are also studied. (C) 2000 American Institute of Physics. [S0021-8979( 00)08809-5].