Engineering and Characterization of Single Photon Emitters in Hexagonal Boron Nitride
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Date
2020-09-24
Authors
Ziegler, Joshua
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Publisher
University of Oregon
Abstract
Single photons have broad applications across quantum information technologies including quantum computation, boson sampling, and quantum communication. Current single photon generation techniques are not ideal due to concerns such as low brightness, stochasticity, or need for low temperatures. The recently discovered single photon emitter in the 2D material hexagonal boron nitride is an interesting single photon source due to its extreme brightness and photoluminescence stability. Moreover, the nanoscale thickness of the material allows for strong coupling to hybrid photonic structures. However, integration of these single photon emitters has not yet been reliably realized due to a large amount of inhomogeneous broadening (which may be due to strain) and difficulties in consistent fabrication of these emitters. If these two problems could be solved, the viability of integrating these emitters would be greatly increased.
Here, we address wavelength variation in boron nitride emitters by identifying a zero-dimensional boron nitride nanostructure that hosts single photon emitters with reduced spectral variation. We find that these emitters in this nanostructure have a wavelength variation reduced by a factor of 5. We offer reasoning that this may be due to the mechanical robustness of the zero-dimensional structure.
In order to reliably fabricate these emitters, we develop a focused ion beam milling technique to create single photon emitters by cutting holes in the hexagonal boron nitride. Optimally tuning the milling parameters, we achieve a 31% yield of sites with the signature of single photon emission and a 94% yield of sites that have the signature of few photon emission.
Together, these two results open the door for large-scale on-chip integration of boron nitride emitters into photonic or plasmonic structures. More engineering is likely needed for further control of emission wavelength as well as reduction of the two-photon probability, but our results will be invaluable for practical uses of hexagonal boron nitride single photon emitters.
This dissertation includes previously published coauthored material.
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Keywords
2D material, hexagonal boron nitride, quantum emitter, solid-state defect