Improved emission intensity of UVC-LEDs from using strain relaxation layer on sputter-annealed AlN

This paper presents the effects of Mg concentration in a Mg-doped aluminum nitride (AlN) strain relaxation layer according to the metalorganic vapor-phase epitaxy method. A UV LED using a Mg-doped AlN strain relaxation layer at a Mg concentration of 3 × 1020 cm−3 on a sputter-annealed AlN template produced light output power 11 times as high as that with conventional LED structures. The AlGaN-on-AlN relaxation rate and LED light output power increased starting from Mg concentrations of 1019 cm−3. These characteristics had almost the same values when the Mg concentration was less than 3 × 1019 cm−3. These results show the improvement of efficiency caused by void formation due to the inversion domain.