Temperature Dependence of Wavelength Selectable Zero-Phonon Emission from Single Defects in Hexagonal Boron Nitride

• Published in: Nano letters Vol. 16; no. 10; pp. 6052 - 6057
• Main Authors: Jungwirth, Nicholas R, Calderon, Brian, Ji, Yanxin, Spencer, Michael G, Flatté, Michael E, Fuchs, Gregory D
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 12.10.2016
• Subjects: zero-phonon line; 2D material; point defect; Single-photon source; hexagonal boron nitride; line width
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.6b01987

We investigate the distribution and temperature-dependent optical properties of sharp, zero-phonon emission from defect-based single photon sources in multilayer hexagonal boron nitride (h-BN) flakes. We observe sharp emission lines from optically active defects distributed across an energy range that exceeds 500 meV. Spectrally resolved photon-correlation measurements verify single photon emission, even when multiple emission lines are simultaneously excited within the same h-BN flake. We also present a detailed study of the temperature-dependent line width, spectral energy shift, and intensity for two different zero-phonon lines centered at 575 and 682 nm, which reveals a nearly identical temperature dependence despite a large difference in transition energy. Our temperature-dependent results are well described by a lattice vibration model that considers piezoelectric coupling to in-plane phonons. Finally, polarization spectroscopy measurements suggest that whereas the 575 nm emission line is directly excited by 532 nm excitation, the 682 nm line is excited indirectly.