Structural design of AlN/GaN superlattices for deep-ultraviolet light-emitting diodes with high emission efficiency

We demonstrate on the basis of first-principles calculations that a AlN/GaN superlattice with one or two GaN monolayers is efficient for near-band-edge C-plane emission of deep-ultraviolet light-emitting diodes. We find that such superlattices lead to a significant increase of the C-plane components of the optical matrix element up to 57% relative to GaN bulk. At the same time, the energy gap of these superlattices is in the deep-UV region, where the shortest emission wavelength is 224 nm. This is remarkably shorter than that in Al-rich AlGaN alloys. (C) 2011 American Institute of Physics. [doi:10.1063/1.3651335]