Dual‐Color Emission from Monolithic m‐Plane Core‐Shell InGaN/GaN Quantum Wells

A dual‐color emission is achieved by combining two monolithic sets of core‐shell multiple quantum wells (MQWs) grown on GaN microwires. The shell heterostructure is composed of 3x blue MQWs and 7x green MQWs with photoluminescence emission covering 400‐450 nm and 450‐550 nm wavelength bands, respectively. Both emissions are coming from the two MQW sets grown on m‐plane sidewall surface, as revealed by cathodoluminescence mapping. Advanced structural characterization combining transmission electron microscopy and energy dispersive X‐ray analysis has been performed on longitudinal cross‐section slices of the wires. Considering asymmetrical QW interface, the In‐content is measured to be equal to 15.7 (±0.5) and 23.5 (±2.0) % in the first and the second MQW set consistent with the blue and green emissions. Extended defects are formed originating from the second MQW set due to higher In‐content. A flexible light-emitting diode (LED) has been fabricated based on these dual core‐shell MQWs showing an electroluminescence dominated by green emission due to efficient hole injection in the In‐rich second MQW set. This work opens the way for multiple color‐emission from core‐shell MQWs for phosphor‐free nanowire‐based LED applications.