Single quantum well deep-green LEDs with buried InGaN/GaN short-period superlattice
Résumé
In spite of the great progress in III-N technology, LEDs with wavelength >530 nm still exhibit low efficiency compared to blue and short-wavelength-green LEDs. Here we report on significant improvement of deep-green LED properties by modifications of the structure design. The combination of InGaN/GaN superlattice followed by low-temperature GaN is the key element to increase the electroluminescence efficiency for deep-green LED. Various techniques were employed to clarify the correlation between structure properties, growth regimes and design. Modification of the defect structure of the GaN buffer by InGaN layers appears to be mostly responsible for the observed effect. LEDs processed and assembled in a standard flip-chip geometry with Ni–Ag p-contact demonstrate external quantum efficiencies of 8–20% in the 560–530 nm range.