Critical thickness of hexagonal GaBN/BN heterostructures

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Abstract

We report the growth of hexagonal boron gallium nitride alloys, h-GaxB1-xN, on hexagonal boron nitride (h-BN) templates by metalorganic chemical vapor deposition and the observation of the critical thickness (LC) phenomenon in the h-GaBN/BN heterostructure system. It was observed that GaxB1-xN alloys in a pure hexagonal phase can be obtained when the film thickness is below LC. X-ray diffraction (XRD) θ-2θ measurement results revealed the formation of separate wurtzite (w)-GaN domains within the h-GaBN matrix when the film thickness is beyond LC. XRD results were supported by photoluminescence spectroscopy which revealed the absence of the band edge emission of w-GaN near 3.4 eV in very thin layers, but an increase in the w-GaN band edge emission with an increase in the h-GaxB1-xN layer thickness beyond LC. Despite the fact that layered structured materials generally possess a weak interlayer interaction, our results revealed that phase separation still occurs in layered h-GaxB1-xN alloys and the critical thickness depends on the Ga composition. The present study also provided insights into possible ways to synthesize layered GaBN/BN heterostructures and quantum wells in the pure hexagonal phase with tunable bandgaps and optical properties, which would open up many new applications.

Original languageEnglish
Article number205703
JournalJournal of Applied Physics
Volume125
Issue number20
DOIs
StatePublished - May 28 2019

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