Processing and thermal properties of highly oriented diamond thin films

Abstract

This paper discusses early research surrounding bias-enhanced nucleation ( BEN) of diamond, which ultimately led to its development as a heteroepitaxial nucleation process. Substrate effects on bias-enhanced nucleation were observed in these early studies, indicating that carbide formers were effective substrates. Later, epitaxial nucleation on (100) β-SiC, (100) Si, and (111) TiC was demonstrated. The thermal attributes of epitaxially textured films have been more recently evaluated by comparing the in-plane thermal conductivity of highly oriented films to those of randomly fiber-textured films. The thermal properties were determined using Joule heating thermometry and indicated room temperature thermal conductivity values of ∼650 and ∼335 W/m K for the respective films. This two-fold improvement is ascribed to reduced phonon scattering at the low angle grain boundaries characterizing the epitaxially textured films. This is further supported by temperature-dependent measurements, which showed a more pronounced sensitivity to these defects within the random fiber-textured films at low measurement temperatures.