k·p Models to study strained-layer quantum-well structures and superlattices

We examine k·p models of varying degree of sophistication for their ability to describe the electronic structure of superlattices and quantum wells fabricated from direct-gap III-V compounds and their alloys. Energy levels of confined states in InAs/In_1-xGa_xAs and GaAs/GaAs_ySb_1-y structures are studied. The importance of the inclusion of nonparabolicity and strain-dependence in the effective masses is demonstrated. In general, one-band models that merely include the shift of band edges can only give a qualitative picture of the energy spectrum. The importance of terms of higher order in strain is discussed.