GaN-based light-emitting diodes with a thermally stable mirror structure underneath an insulating SiO₂ layer

This study reports the development of GaN-based light-emitting diodes (LEDs) with Ni/Ag (1 nm ± 0.2 nm/ 100 nm ± 2 nm) layers underneath an insulating layer of SiO₂ .The resultsof this study confirm the thermal stability of a Ni/Ag mirror with reflectance of 90.6 ± 1.5% following thermal annealing at 5008C for 5 min. This approach achieves farsuperior current spreading and prevents the absorption of light through the use of an opaque p-pad electrode. With 20-mA current injection, the output power of the LED with SiO₂ /Ni/Ag layers was 6.5 and 12.1% greater than that of LEDs with and without a SiO₂ layer, respectively. Furthermore, the 20-mA forward voltage increased only slightly from 3.03 ± 0.01 to 3.05 ± 0.01 V for LEDs with SiO₂ /Ni/Ag layers. Good reliability is also achieved for LEDs with SiO₂/Ni/Ag layers.