Nils Bernhardt
Institute of Solid State Physics, Technische Universität Berlin, Berlin, Germany
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Hexagonal boron nitride (hBN) is widely known for its bright and stable defect luminescence over a broad spectral range, complementing its intrinsic band-edge emission. While well-established color centers, such as the 4.1eV (303nm) defect luminescence commonly attributed to carbon dimers [1,2], have received considerable study, many novel emitters continue to emerge. In this work, we report a previously unobserved UV luminescence band with sharp emission peaks ranging from 374 to 400 nm. We show that introducing aluminum during the MOVPE growth of hBN [3], while not essential, enables straightforward scalability of the color
center’s intensity. Promising better control over defect formation than other hBN UV defect emitters, this engineerability may open new avenues for device designs and further advance hBN-based applications in quantum photonics, integrated optoelectronic circuits, and sensing technologies.
This investigation provides a comprehensive study of the emission intensity, excitation channels, and carrier dynamics as a function of temperature for these emitters. We employ photoluminescence excitation (PLE) spectroscopy alongside temperature-dependent and time-resolved photoluminescence spectroscopy measurements to explore the origin and properties of this newly identified luminescence band. A comparative analysis with the indirect excitonic bandgap luminescence of hBN, its phonon coupling, and the 4.1eVcolor center yields insights into potential defect mechanisms.
Our results promote the understanding of how material composition tuning affects defect formation and luminescence characteristics in hBN for the UV spectral region by establishing a direct correlation between growth conditions and luminescence intensity. This work expands the range of accessible hBN color centers and opens new opportunities for the fabrication of quantum emitters in emerging optoelectronic devices.
References
[1] Plo et al., arXiv:2405.20837 (2024).
[2] Iwański et al., npj 2D Mater Appl 8, 72 (2024).
[3] Iwański et al., arXiv:2305.15810 (2023).
Email: nils.bernhardt@tu-berlin.de