Orthogonalized-moment method and the study of the electronic structure of heterostructures: Application to CdTe/ZnTe superlattices

We present an approach that uses power moments of the Hamiltonian to calculate the electronic states in low-dimensional structures, such as quantum wells or superlattices. From a microscopic tight-binding description of the crystals, the orthogonalized moments of the Hamiltonian are used to obtain the coefficients of the continued fraction representing the density of the electronic states. This method allows us to calculate quite efficiently the electronic states of large-period systems and clusters. Application to a one-dimensional quantum-well model shows the ability of the method to determine the localized states with good accuracy. Then, we calculate the electronic structure of a strained CdTe/ZnTe superlattice and we study the dependence of the highest valence states at the center of the Brillouin zone, with respect to the valence-band offset. Existence of type-I–type-II transition for a critical value of the valence-band offset is brought out.