Growth and characterization of II–VI blue light-emitting diodes using short period superlattices

We investigate the properties of II–VI short period superlattice (SPSL) blue light-emitting diodes grown by molecular beam epitaxy. The device consists of a ZnSe active layer, SPSL MgZnSSe cladding layers, and a ZnSeTe digital graded contact. The SPSL structure is made of alternating layers of MgSe, ZnSe, ZnS, and ZnSe. Highly ordered SPSL layer structures are successfully grown. Tweedlike contrast is observed in the pseudomorphic SPSL from our transmission electron microscopy analysis. The device shows high purity blue emission at 460 nm at room temperature with a 13 nm full width at half maximum. Operating at 14 A/cm2, the half-intensity lifetime is more than 13 h at room temperature with an external quantum efficiency of ∼0.1%.