MOVPE van der Waals epitaxial growth of AlGaN/AlGaN multiple quantum well structures with deep UV emission on large scale 2D h-BN buffered sapphire substrates

We report wafer-scale growth and mechanical exfoliation of 20 periodAl0.58Ga0.42N/Al0.37Ga0.63N multiple quantum wells (MQWs) on h-BN buffered templates and compare them to control samples of the same structure on AlN templates. X-ray diffraction measurements of the MQW structure on h-BN clearly featured satellite peaks up to third order in the 2θ−ω scans indicating good MQW periodicity. Detailed transmission electron microscope (TEM) analysis show good heterointerface quality in the structure and large V-pits on the surface. Depth resolved cathodoluminescence of the MQWs on h-BN revealed a UV emission peak at 299 nm and a sharp shoulder at 292 nm. We also report lift-off and transfer of the MQW on the h-BN structure and have investigated post-transfer optical emission, which demonstrates good preservation of optical emission characteristics. Together these results show the suitability of h-BN buffers for the realization of free-standing or flexible optical devices emitting in the deep UV region.