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Wurtzite BAlN alloy with large bandgap is an emerging material system for UV optoelectronic and power devices. In this study, the BAlN/GaN heterojunction with a sharp interface and uniform distribution of the elements was formed by careful control of epitaxial conditions to avoid GaN desorption and parasitic reactions whose band alignment was then measured for the first time. The valence band offset (VBO) was found to be nearly-zero, i.e. −0.2 ± 0.2 eV, in the B 0.14 Al 0.86 N/GaN heterojunction by X-ray photoelectron spectroscopy. Additionally, the conduction band offset (CBO) is estimated at 2.1 ± 0.2 eV, which is the largest reported CBO among epitaxial GaN-based heterojunctions. In comparison to the type-I Al 0.75 Ga 0.25 N/GaN heterojunction (both Al 0.75 Ga 0.25 N and B 0.14 Al 0.86 N alloy have the same bandgap of 5.7 eV), the CBO and VBO of the B 0.14 Al 0.86 N/GaN heterostructure are significantly larger and smaller, respectively. The nearly-zero VBO and the very large CBO of the B 0.14 Al 0.86 N/GaN heterojunction could potentially lead to considerable performance enhancement for GaN optoelectronics and power electronics devices. [ABSTRACT FROM AUTHOR]

• The hybrid graphene quantum dots (GQDs)/ZnO nanoflowers (NFs) were fabricated. • The large surface area of ZnO NFs leads to more efficient integration of GQDs. • The hybrid GQD/ZnO NFs structure showed strong photoluminescence emission. • The radiative recombination can be enhanced by energy transfer phenomena. We report the fabrication of hybridization between graphene quantum dots (GQDs) and ZnO nanoflowers (NFs) for mediating photoluminescence by using a straightforward solution-based technique. Hydrothermally grown two-dimensional ZnO NFs played an essential role in assembling GQDs. The large surface area to volume ratio of ZnO NFs led to a highly dense distribution of GQDs, giving rise to photoluminescence (PL) emission at around 442 nm from GQDs and the synergic effects. Thus, GQDs/ZnO hybrid results in strong and broad PL over the spectral range from near UV to red region. We also suggested that an energy interaction between GQDs and various defect sites in ZnO NFs can promote the radiative recombination of both components, thereby providing PL peak intensities more than two times higher than individual components. Fabricated GQDs/ZnO heterojunctions on both soft and hard substrates emit similar intense and wide PL spectrum under ultraviolet irradiation, indicating that this heterojunction can consider as a promising platform for flexible and transparent optoelectronic applications. [ABSTRACT FROM AUTHOR]