Telecom-wavelength C-band emission in carbon doped h-BN

Carbon-doped and unintentionally doped freestanding hexagonal boron nitride (h-BN) quasi-bulk crystals have been produced by hydride vapor phase epitaxy and characterized by photoluminescence (PL) emission spectroscopy in the infrared telecom-wavelength C-band region. A sharp, distinct emission line was observed at 0.807 eV (∼1.54 μm). This emission was uniquely identified in carbon-doped h-BN wafers and was notably absent in undoped samples. Through PL analysis using dual below-bandgap excitation sources for samples with varying crystalline quality and doping concentration, our results suggest that the formation of carbon-related complexes is the primary requirement for this 0.807 eV emission. Drawing on a recent theoretical model of (CB–VB) complexes in cubic BN, we attribute this newly observed 0.807 eV emission in h-BN to a similar (CB–VB) configuration, potentially acting as a quantum qubit. These findings demonstrate a novel pathway for achieving atomic-like transitions at 1.54 μm within an ultrawide bandgap semiconductor host, offering implications for integrated quantum photonics and secure telecommunications.