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Dielectric spectroscopy of hydrogen treated hexagonal boron nitride ceramics

Cuenca, Jerome A., Mandal, Soumen, Morgan, David J., Snowball, Malcolm, Porch, Adrian and Williams, Oliver A. 2020. Dielectric spectroscopy of hydrogen treated hexagonal boron nitride ceramics. ACS Applied Electronic Materials 2 (5) , pp. 1193-1202. 10.1021/acsaelm.9b00767

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Hexagonal boron nitride (h-BN) is a critical material for 2D electronic devices and has attracted considerable attention owing to its structural similarity to graphene. However, it is a dielectric and modifying its electrical properties is a challenge. Hydrogenation has been calculated as a potential method, although is rarely experimentally measured. Here, dielectric spectroscopy of hot-pressed h-BN after various hydrogen treatments has been investigated. Untreated h-BN showed a frequency independent dielectric constant (4.2±0.2) and an immeasurably low dielectric loss factor, demonstrating the ideal dielectric nature of h-BN across the 103 to 1010 Hz range. However, hydrogen plasma (H+) treatment in a microwave chemical vapour deposition (CVD) reactor amplified the complex permittivity dramatically, introducing Havriliak-Negami (HN) type dispersion (εs ≈ 20 ± 2, ε∞ ≈ 4.2 ± 0.2) and a percolating long range conductivity (∼ 0.32 mS/m). Annealing in molecular hydrogen (H2) at similar CVD temperatures showed minimal impact, implying that H2 diffusion is not the cause. Oxygen plasma treatment, however, removes the percolating conductivity but the Debye mechanism remains. This leads to the conclusion that the electrical conductivity of h-BN ceramics can be modified through hydrogenation, using atomic hydrogen. The potential as a tunable wide-band gap semiconductor is highlighted however for insulating dielectric substrate applications, microwave CVD may destroy these desirable properties.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Physics and Astronomy
Publisher: ACS
ISSN: 2637-6113
Date of First Compliant Deposit: 3 April 2020
Date of Acceptance: 30 March 2020
Last Modified: 10 Oct 2021 09:47

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