# Mitigating the Thermal Bottleneck in Polycrystalline Diamond Films by Gradient ICP Etching of the Nucleation Layer

## TL;DR

This paper shows how removing a defect-rich layer in diamond films improves their thermal conductivity, offering a new method to enhance heat transfer in these materials.

## Contribution

The study introduces a post-growth method using ICP etching to reduce thermal resistance in diamond films.

## Key findings

- Thermal conductivity increased from 1549.9097 to 1792.0250 W·m−1·K−1 after 5 h of etching.
- Defects and non-diamond carbon decreased as confirmed by XRD and Raman analyses.
- The method provides a validated route to enhance thermal transport in thick diamond films.

## Abstract

A defect-rich nucleation layer near the substrate is widely regarded as a key thermal bottleneck in thick polycrystalline diamond films. Here, we quantitatively evaluate this effect by progressively removing the nucleation layer via depth-controlled inductively coupled plasma (ICP) etching and measuring the thermal conductivity. The thermal conductivity increases from 1549.9097 W·m−1·K−1 (as-grown) to 1656.1743 W·m−1·K−1 (1 h), 1783.3763 W·m−1·K−1 (3 h), and 1792.0250 W·m−1·K−1 after 5 h of etching, consistent with the reduction of defects and non-diamond carbon revealed by X-ray diffraction (XRD) and Raman analyses. These results provide a quantitative, depth-resolved validation of the nucleation-layer thermal resistance and establish an effective post-growth route to enhance thermal transport in thick polycrystalline diamond films.