A Theoretical Investigation of the Metastability of Epitaxial Zinc-Blende CdSe on (100) Zinc-Blende Substrate

The metastability of zinc-blende (cubic) CdSe on (100) zinc-blende substrate is discussed based on cohesive energy calculations for bulk form and thin layers of CdSe using the pseudopotential perturbation approach and universal empirical potentials. In the bulk form, zinc-blende CdSe is found to be less stable than wurtzite CdSe by 10 (meV/atom). However, the wurtzite CdSe on the (100) zinc-blende ZnTe substrate is destabilized because of a large deviation in the atomic coordination number at the wurtzite/zinc-blende interface from the ideal coordination number Z=4 for tetrahedrally bonded semiconductors, which leads to a higher energy of 500 (meV/atom) compared to that at a zinc-blende/zinc-blende interface. Theses findings suggest that zinc-blende CdSe can be grown on the (100) zinc-blende substarate.