Analysis of the capability of HREM applied to quantum heterostructures

This work analyzes the possibilities offered by HREM for the observation of quantum heterostructures. Multilayers of Cu/Pd, Fe/Ag and Ag/Si are constructed by using a molecular dynamics simulation method and the configuration of the electronic charge at the interfaces is obtained from a Hartree-Fock calculation of the type extended Debye-Hueckel approximation. The HREM image of the multilayers is calculated by using a standard dynamical diffraction method. MD simulations show that in all cases good epitaxis can be achieved. However the interfacial regions have a complex structural and electronic configuration which is significantly different from the bulk reference state. As these regions span few monolayers across their observation is extremely critical. The HREM image of the films is clear. The interfaces and defective epitaxial growth can be observed. An interesting possibility for future developments appears to be offered by the availability of the interfacial potential obtained from the HREM image intensity.