Suppression of the subband parasitic peak by $1nm$ $i-AlN$ interlayer in AlGaN deep ultraviolet light-emitting diodes

The origin and suppression of the subband parasitic peak in AlGaN deep ultraviolet light-emitting diodes have been studied. The parasitic peak is clarified to come from a $p-AlGaN$ cladding layer and to be related to Mg dopants. By using $1nm$ $i-AlN$ as an interlayer between the active region and the $p-AlGaN$ cladding layer, this peak is suppressed efficiently. The devices with such an interlayer show improved output power by a factor of 4 at injection current density of $20A∕cm2$⁠, except that the series resistance and turn-on voltage are slightly increased.