Table 1.
Synthesis method, thickness, and grain size of the as-deposited and annealed Cu films at 500 °C
| STEM thickness of as-deposited PVD films (nm) | Grain size of as-deposited PVD films (nm) | STEM thickness of annealed PVD films (nm) | Grain size of annealed PVD films (nm) | STEM thickness of as-deposited PVD-EP films (nm) | Grain size of as-deposited PVD-EP films (nm) | STEM thickness of annealed PVD-EP films (nm) | Grain size of annealed PVD-EP films (nm) |
|---|---|---|---|---|---|---|---|
| ≈27.0 | 22.8 ± 4.6 | ≈27.0 | 21.6 ± 5.2 | ≈44.0 | 29.2 ± 8.2 | ≈43.0 | 34.6 ± 6.8 |
| ≈57.0 | 32.9 ± 7.2 | ≈57.0 | 49.4 ± 7.3 | ≈109.0 | 62.7 ± 15.9 | ≈119.0 | 125.8 ± 13.9 |
| ≈118.0 | 75.2 ± 14.1 | ≈119.0 | 113.4 ± 13.4 | ≈595.0 | 289.9 ± 37.8 | ≈559.0 | 672.1 ± 170.8 |
| ≈1108.0 | 926.8 ± 173.8 | ||||||
| ≈5550.0 | 978.3 ± 290.6 |
The thickness and grain size of the films are determined over a large area. We find that the thickness of PVD films is uniform. Thick PVD-EP films (thickness of ≈109 nm or greater) exhibit non-uniform thickness (see also in Supporting information). However, this variation does not impact the in-plane thermal conductivity trends, as both the grain size and film thickness are significantly larger than the electron mean free path. The grain size does not vary much for as-deposited PVD and PVD-EP films having comparable thicknesses.