Heterostructures of GaN with SiC and ZnO enhance carrier stability and separation in framework semiconductors

A computational approach, using the density functional theory, is employed to describe the enhanced electron-hole stability and separation in a novel class of semiconducting composite materials, with the so-called double bubble structural motif, which can be used for photocatalytic applications. We examine the double bubble containing SiC mixed with either GaN or ZnO, as well as related motifs that prove to have low formation energies. We find that a 24-atom SiC sodalite cage inside a 96-atom ZnO cage possesses electronic properties that make this material suitable for solar radiation absorption applications. Surprisingly stable, the inverse structure, with ZnO inside SiC, was found to show a large deformation of the double bubble and a strong localisation of the photo-excited electron charge carriers, with the lowest band gap of ca. 2.15 eV of the composite materials considered. The nanoporous nature of these materials could indicate their suitability for thermoelectric applications.