Origin of exciton emissions from an AlN p-n junction light-emitting diode

Exciton emissions from an AlN light-emitting diode with an improved emission efficiency of 1×10−4% were observed at 5.94 eV (208.7 nm) and 6.10 eV (203.2 nm) by current injection. The emission at 5.94 eV is attributed to an exciton emission originating from the crystal-field split off valence band (CH-exciton emission). Due to the large carrier-phonon interaction, the CH-exciton emission accompanies its phonon replicas. The emission at 6.10 eV is attributed to another exciton emission originating from heavy/light hole valence bands (HH/LH-exciton emission). From the emission energies, considering residual strain, the crystal-field splitting energy was determined to be −165 meV.