Origin of defect luminescence in ultraviolet emitting AlGaN diode structures

Light emitting diode structures in the ultraviolet spectral range are investigated. The samples exhibit defect luminescence bands. Synchrotron-based photoluminescence excitation spectroscopy of complicated multi-layer stacks is employed to assign origin observed certain layers. In case quantum well at 320 and 290 nm, n-type contact AlGaN:Si layer found be bands between 2.65 2.8 eV. For 230 nm emitters without such layer, a double structure 3.6 eV can assigned wells.