Beryllium chalcogenides for ZnSe-based light emitting devices

Beryllium-containing ZnSe-based compound semiconductors introduce substantial additional degrees of freedom for the design of wide gap II–VI heterostructures. An overview of the advantages of beryllium chalcogenides is given here. A variety of BeTe-ZnSe and BeMgZnSe-ZnSe structures has been fabricated by molecular beam epitaxy, and their structural, optical and electrical properties have been investigated. The main aspects are the lattice matching of BeTe with its high lying valence band and high p-type dopability, the possibility to grade the valence band of GaAs down to the one of ZnSe by using a lattice matched ZnSe-BeTe pseudograding, the use of beryllium instead of sulphur for high band gap claddings, as well as the expected strengthening of beryllium compounds as compared to the standard materials used today on the basis of ZnMgSSe.