arXiv subjects

Tin S. Cheng

Publications and source records attributed to Tin S. Cheng.

3 recordsLinked to original sources

arXiv2026

In-situ Silicon Doped hBN by High-Temperature Molecular Beam Epitaxy Enables Single Photon Emission

Hexagonal boron nitride (hBN) has emerged as a leading host for optically active quantum defects. Yet introduction of specific impurity species other than carbon remains unexplored. Here, we demonstrate an in-situ silicon doping of hBN grown by high-temperature molecular beam epitaxy (HT-MBE). By systematically varying the growth temperature from 900 to 1390 °C under a constant silicon flux, we establish an optimal window for Si incorporation to host a diverse range of emitters from 430-750 nm at room temperature. By transferring silicon-doped hBN film on SiO$_2$ substrate, we verified that single photon emitter activity was sustained in the hBN, demonstrating compatibility with device integration. The plausible origins of the observed optical transitions were discussed, and several potential candidates were proposed. Our results demonstrate a step toward a comprehensive understanding of in-situ doping of hBN and its utilization for quantum photonic applications.

physics.optics↗

arXiv2025

Optically detected magnetic resonance of wafer-scale hexagonal boron nitride thin films

Hexagonal boron nitride (hBN) has recently been shown to host native defects exhibiting optically detected magnetic resonance (ODMR) with applications in nanoscale magnetic sensing and imaging. To advance these applications, deposition methods to create wafer-scale hBN films with controlled thicknesses are desirable, but a systematic study of the ODMR properties of the resultant films is lacking. Here we perform ODMR measurements of thin films (3-2000nm thick) grown via three different methods: metal-organic chemical vapour deposition (MOCVD), chemical vapour deposition (CVD), and molecular beam epitaxy (MBE). We find that they all exhibit an ODMR response, including the thinnest 3nm film, albeit with different characteristics. The best volume-normalised magnetic sensitivity obtained is 30uT/sqrt(Hz um^3). We study the effect of growth temperature on a series of MOCVD samples grown under otherwise fixed conditions and find 800-900C to be an optimum range for magnetic sensitivity, with a significant improvement (up to two orders of magnitude) from post-growth annealing. This work provides a useful baseline for the magnetic sensitivity of hBN thin films deposited via standard methods and informs the feasibility of future sensing applications.

cond-mat.mtrl-sci↗

arXiv2020

Identifying Carbon as the Source of Visible Single Photon Emission from Hexagonal Boron Nitride

Single photon emitters (SPEs) in hexagonal boron nitride (hBN) have garnered significant attention over the last few years due to their superior optical properties. However, despite the vast range of experimental results and theoretical calculations, the defect structure responsible for the observed emission has remained elusive. Here, by controlling the incorporation of impurities into hBN and by comparing various synthesis methods, we provide direct evidence that the visible SPEs are carbon related. Room temperature optically detected magnetic resonance (ODMR) is demonstrated on ensembles of these defects. We also perform ion implantation experiments and confirm that only carbon implantation creates SPEs in the visible spectral range. Computational analysis of hundreds of potential carbon-based defect transitions suggest that the emission results from the negatively charged VBCN- defect, which experiences long-range out-of-plane deformations and is environmentally sensitive. Our results resolve a long-standing debate about the origin of single emitters at the visible range in hBN and will be key to deterministic engineering of these defects for quantum photonic devices.

physics.app-ph↗