Band offsets and stability of BeTe/ZnSe (100) heterojunctions

We present ab initio studies of band offsets, formation energy, and stabili ty of (100) heterojunctions between (Zn,Be)(Se,Te) zinc-blende compounds, a nd in particular of the lattice-matched BeTe/ZnSe interface. Equal band off sets are found at Be/Se and Zn/Te abrupt interfaces, as well as at mixed in terfaces, in agreement with the established understanding of band offsets a t isovalent heterojunctions. Thermodynamical arguments suggest that islands of non-nominal composition may form at the interface, causing offset varia tions over similar to0.8 eV depending on growth conditions. Our findings re concile recent experiments on BeTe/ZnSe with the accepted theoretical descr iption.