In-situ monitoring of microwave plasma-enhanced chemical vapour deposition diamond growth

Leigh, William 2022. In-situ monitoring of microwave plasma-enhanced chemical vapour deposition diamond growth. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

With a wealth of extreme properties, including the highest thermal conductivity of any known material, diamond is a highly desirable material for a wide range of applications. However, the growth of high-quality diamond films on heterogeneous materials can be challenging. With the properties of diamond films highly dependent on the substrate temperature during growth, non-uniform substrate temperature will result in the growth of inhomogeneous films. Chapter 4 details the development of an inexpensive temperature mapping system, combining dual wavelength pyrometry with a mirror galvanometer to produce substrate temperature maps under growth conditions. Temperature maps produced are compared to finite element simulations and spectroscopic ellipsometry and Raman spectra, with good agreement between the results. As well as substrate temperature, the quality of diamond films is dependent on the early stages of growth. In Chapter 5, spectroscopic ellipsometry is applied to the initial stages of diamond growth on silicon. Ex-situ spectra are used to develop an optical model for characterisation, which is then applied to in-situ spectra. The model identified the point of coalescence of crystallites into a single film through a decrease in bulk void content followed by a spike in sp2 content. Ex-situ Raman spectra and atomic force microscopy images were used to validate the model. One potential application of diamond is for thermal management of gallium nitride devices, with potential growth routes on an aluminium nitride interlayer atop the GaN stack. This application is limited by a thermal resistance associated with the disordered transition region formed in the early stages of growth. Chapter 6 utilises spectroscopic ellipsometry for in-situ monitoring of the early stages of diamond growth on AlN, with observations again verified by Raman spectroscopy and atomic force microscopy images.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Physics and Astronomy
Subjects:	Q Science > QC Physics
Uncontrolled Keywords:	Diamond, CVD, Monitoring, Ellipsometry, Pyrometry
Funders:	EPSRC Diamond CDT
Date of First Compliant Deposit:	27 June 2023
Last Modified:	27 Jun 2023 09:49
URI:	https://orca.cardiff.ac.uk/id/eprint/160613

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