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Highlights • h-BN were grown on sub-micron size dome patterned sapphire substrates. • Wrinkled morphology of layered h-BN was obtained on c -plane sapphire. • On the domes, h-BN were different demonstrating anisotropy. • TEM confirmed h-BN is layered and continuous with turbostratic islands on domes. • 320 nm peak intensity increase confirms the TEM observations. Abstract Layered h-BN were grown on sub-micron size dome patterned sapphire substrates (PSS) by metal organic vapor phase epitaxy (MOVPE) to study the effects of substrate orientations, strain and subsequent thermal stress evolution. Electron micrograph images on the surface of the c -plane sapphire in-between the dome structures show typical wrinkled morphology of layered h-BN, similar to the reference sample surface confirming the high quality h-BN growth. However, the h-BN morphology on the domes exhibited pattern like folding which were drastically different from the h-BN on the c -plane sapphire. Detailed TEM studies show that the h -BN is layered and covers the dome patterns of the sapphire substrates like a "blanket of snow" continuously with localized strain variations induced turbostratic phase insertions. In addition, the local variation in optical emission properties of layered materials, which are dramatically affected by the rippled morphology were also investigated using depth resolved cathodoluminescence. The intensity variation of the 320 nm peak confirms that the BN on dome structures have more strain related defects than the c -plane h-BN. Thus, these results give better insight on the origin of turbostratic BN grains and local control over the structural and optical emission characteristics. [ABSTRACT FROM AUTHOR]

Highlights • Demonstrated growth and mechanical exfoliation of MQWs on h-BN templates. • Obtained satellite peaks on the MQWs structure on h-BN indicating good periodicity. • Good heterointerface quality was confirmed with TEM analysis. • Depth resolved CL shows double MQW emission peaks. • After lift-off CL analysis confirmed good preservation of optical functionalities. Abstract We report wafer-scale growth and mechanical exfoliation of 20 periodAl 0.58 Ga 0.42 N/Al 0.37 Ga 0.63 N 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. [ABSTRACT FROM AUTHOR]