Monitoring of the initial stages of diamond growth on aluminum nitride using in situ spectroscopic ellipsometry

Leigh, William, Mandal, Soumen ORCID: https://orcid.org/0000-0001-8912-1439, Cuenca, Jerome A. ORCID: https://orcid.org/0000-0003-1370-1167, Wallis, David ORCID: https://orcid.org/0000-0002-0475-7583, Hinz, Alexander M., Oliver, Rachel A., Thomas, Evan L. H. and Williams, Oliver ORCID: https://orcid.org/0000-0002-7210-3004 2023. Monitoring of the initial stages of diamond growth on aluminum nitride using in situ spectroscopic ellipsometry. ACS Omega 8 (33) , pp. 30442-30449. 10.1021/acsomega.3c03609

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Abstract

The high thermal conductivity of polycrystalline diamond makes it ideally suited for thermal management solutions for gallium nitride (GaN) devices, with a diamond layer grown on an aluminum nitride (AlN) interlayer atop the GaN stack. However, this application is limited by the thermal barrier at the interface between diamond and substrate, which has been associated with the transition region formed in the initial phases of growth. In this work, in situ spectroscopic ellipsometry (SE) is employed to monitor early-stage microwave plasma-enhanced chemical vapor deposition diamond growth on AlN. An optical model was developed from ex situ spectra and applied to spectra taken in situ during growth. Coalescence of separate islands into a single film was marked by a reduction in bulk void fraction prior to a spike in sp2 fraction due to grain boundary formation. Parameters determined by the SE model were corroborated using Raman spectroscopy and atomic force microscopy.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	American Chemical Society
ISSN:	2470-1343
Funders:	EPSRC
Date of First Compliant Deposit:	15 August 2023
Date of Acceptance:	28 July 2023
Last Modified:	06 Jan 2024 02:38
URI:	https://orca.cardiff.ac.uk/id/eprint/161704

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