Effect of coalescence layer thickness on the properties of thin-chip InGaN/GaN light emitting diodes with embedded photonic quasi-crystal structures

The simulation, fabrication and optical characterization of InGaN/GaN MQW-LEDs grown by MOVPE over embedded photonic quasi-crystals (PQCs) are reported. Fully coalesced GaN layers as thin as 140 nm were grown over 1200 nm high air-gap PQCs using an intermittent pulsed/normal growth method. Simulations and angle-resolved photoluminescence measurements reveal there are strong interactions between the embedded PQC and a wide range of trapped modes as well as the dominant low order mode. The interaction with a dominant low order mode is most pronounced when the LED cavity above the embedded PQC has fewer guided modes.