Piotr Tatarczak
University of Warsaw, Warsaw, Poland _______________________________________
Emission of single photon-emitters (SPEs) in layered BN covers almost the entire visible spectral range. The presence of carbon impurities plays a crucial role in the formation of these color centers [1], but their nature is still not fully explained. Many defect-related studies rely on post-growth carbon incorporation into bulk BN flakes requiring additional equipment and time and suffering from limited reproducibility. On the other hand, using metal-organic precursors allows for the introduction of carbon-related impurities directly during the growth process. Achieving appropriate growth conditions for large-area material epitaxy could be a milestone in establishing BN as a robust platform for quantum technologies.
In this work, we systematically compare large-area (2-inch) sp2 BN layers grown by MOVPE on sapphire substrates [2, 3] by the use of different triethylboron (TEB) to ammonia (NH3) ratios. Fig. 1. presents the impact of changes in TEB flow, while maintaining a constant NH3 flow, on the properties of the grown BN. Low TEB flows lead to a negligible carbon concentration and limit the BN growth rate. Higher TEB flows accelerate the growth of high-quality BN and enhance the density of carbon-associated emitters. However, excessively high TEB flows favor the formation of large defect clusters over individual point defects, resulting in lower structural quality of BN, thereby making it unsuitable for integration with photonic structures. As shown in Fig. 2, changes in TEB flow also affect the energy distribution of emitters. The room temperature photoluminescence mapping shows two groups of emitters close to 2.3 eV, but for higher TEB flows their emission distributions overlap. These observations indicate that precise TEB flow adjustments are necessary to balance the BN growth rate and structural quality as well as the generation and properties of SPEs. A more detailed analysis of the impact of TEB flow on emitters’ properties will be provided.
Acknowledgement: This work is supported by the National Science Centre (2020/39/D/ST7/02811, 2022/45/N/ST7/03355)
References:
[1] N. Mendelson et al., Nat. Mater. 20, 321–328 (2021)
[2] A. K. Dąbrowska et al., 2D Mater. 8, 015017 (2021)
[3] M Tokarczyk et al., 2D Mater. 10, 025010 (2023)
Email: Piotr.Tatarczak@fuw.edu.pl