Hexagonal Boron Nitride Substrates for High-Performance Quantum Dot Light-Emitting Devices

Semiconductor quantum dots (QDs) have potential applications in the field of integrated quantum optics including quantum-computing, quantum key distribution and secure data transmission. Charge carrier dynamics and radiative recombination process within QDs are highly dependent on the crystallinity and defects within the supporting substrates as well as the interface. We show that this dependence can be potentially lifted through van der Waals bonded QD/two-dimensional hexagonal boron nitride (hBN) heterostructures. Epitaxy of wetting layer free GaN QDs on layered hBN and morphology control were successfully demonstrated, wherein the GaN QDs are free of threading dislocations and stacking faults. Unlike QDs covalently bonded to substrate, multiple crystallographic orientations were observed in QDs bonded through van der Waals interactions. Moreover, unexpected efficient radiative recombination process was obtained from GaN QDs on hBN with the photoluminescence emission intensity significantly stronger compared with QDs synthesized on AlN and Si substrates while the QD density on hBN is 1-2 orders of magnitude lower. This work provides a new strategy for synthesizing high quality QDs structure which can enable next-generation high performance optoelectronic and quantum devices.