Improved light-output power of InGaN-based multiple-quantum-well light-emitting diodes by GaN/InAlGaN/GaN multi-barrier

• InGaN/GaN-based LED structures were grown on c-plane sapphire substrates by metal-organic chemical vapor deposition (MOCVD).
• We inserted thin InAlGaN layer into the GaN barrier in the form of multi-layer barrier (MLB).
• For LED with MLB, efficiency and optical power were improved significantly.

InGaN/GaN-based LED structures were grown on c-plane sapphire substrates by metal-organic chemical vapor deposition (MOCVD). We inserted thin InAlGaN layer into the GaN barrier in the form of multi-layer barrier (MLB) and investigated the effect of MLB on the performance of InGaN/GaN-based LEDs. MLB consisted of GaN/InAlGaN/GaN layers by replacing conventional GaN single barrier. Lateral LED chips (375 μm × 435 μm) were fabricated and also evaluated by light–current–voltage (L–I–V) measurements. The effect of MLB on surface morphologies of MLB was investigated by atomic force microscopy (AFM). For LED with MLB, efficiency and optical power were improved significantly although there was still efficiency degradation with injection current. This indicates that InAlGaN layer in MLB was helpful to reduce the electron overflow. From photoluminescence (PL) and atomic force microscopy (AFM) measurement, it was revealed that the adoption of MLB for LED was also beneficial to improve the crystal quality of MQWs.