Bandgap and exciton binding energies of hexagonal boron nitride probed by photocurrent excitation spectroscopy

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Abstract

Photocurrent excitation spectroscopy has been employed to probe the band structure and basic parameters of hexagonal boron nitride (h-BN) epilayers synthesized by metal-organic chemical vapor deposition. Bias dependent photocurrent excitation spectra clearly resolved the band-to-band, free exciton, and impurity bound exciton transitions. The energy bandgap (Eg), binding energy of free exciton (Ex), and binding energy of impurity bound exciton (Ebx) in h-BN have been directly obtained from the photocurrent spectral peak positions and comparison with the related photoluminescence emission peaks. The direct observation of the band-to-band transition suggests that h-BN is a semiconductor with a direct energy bandgap of Eg = 6.42 eV at room temperature. These results provide a more coherent picture regarding the fundamental parameters of this important emerging ultra-wide bandgap semiconductor.

Original languageEnglish
Article number102101
JournalApplied Physics Letters
Volume109
Issue number12
DOIs
StatePublished - Sep 19 2016

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