Spectroscopic Ellipsometry of Nanocrystalline Diamond Film Growth.

Evan L H Thomas,Oliver A Williams,John Emyr Macdonald,Chia-Liang Cheng,Soumen Mandal,Ashek-I-Ahmed Ashek-I-Ahmed,Jonathan Rawle,Thomas G Dane

doi:10.1021/acsomega.7b00866

Abstract

With the retention of many of the unrivaled properties of bulk diamond but in thin-film form, nanocrystalline diamond (NCD) has applications ranging from micro-/nano-electromechanical systems to tribological coatings. However, with Young’s modulus, transparency, and thermal conductivity of films all dependent on the grain size and nondiamond content, compositional and structural analysis of the initial stages of diamond growth is required to optimize growth. Spectroscopic ellipsometry (SE) has therefore been applied to the characterization of 25–75 nm thick NCD samples atop nanodiamond-seeded silicon with a clear distinction between the nucleation and bulk growth regimes discernable. The resulting presence of an interfacial carbide and peak in nondiamond carbon content upon coalescence is correlated with Raman spectroscopy, whereas the surface roughness and microstructure are in accordance with values provided by atomic force microscopy. As such, SE is demonstrated to be a powerful technique for the characterization of the initial stages of growth and hence the optimization of seeding and nucleation within films to yield high-quality NCD.

Highlights

Through the advent of nanocrystalline diamond (NCD), many of the superlative properties of diamond are available in a largearea, heteroepitaxial thin-film form at a fraction of the cost of bulk diamond.[1]
Further depolarization was fitted manually to account for thickness nonuniformity, leading to minor improvements in mean square error (MSE) with little modification to the structural parameters reported previously
Spectroscopic ellipsometry (SE) has been applied to the initial stages of nanocrystalline diamond growth atop nanodiamond-seeded silicon substrates, with the resulting trends validated with atomic force microscopy (AFM), scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD)

Summary

Introduction

Through the advent of nanocrystalline diamond (NCD), many of the superlative properties of diamond are available in a largearea, heteroepitaxial thin-film form at a fraction of the cost of bulk diamond.[1]. Any native oxide not covered by diamond growth will be etched by the predominantly hydrogen plasma, allowing the formation of an amorphous/β-SiC layer from carbon reaction with the diamond seeds.[7−10]

Objectives

Methods

Results

Conclusion