Fig. 1 Measured samples and patterning dimension definition. Scanning electron microscopy (SEM) images of amorphous Si3N4 PnCs. (A) Overall image of the sample. Al pads are deposited on the center and the edges of the suspended bridge for the thermal conductivity measurement. High-magnification SEM image of the aligned through-holes creating PnCs for pitch sizes of (B) 36 nm, (C) 100 nm, (D) 200 nm, and (E) 800 nm. The definition of pitch size P and minimum neck width n is illustrated in (E).
Fig. 2 Material thermal conductivity of amorphous Si3N4 PnCs. Material thermal conductivity of amorphous Si3N4 thin films plotted as a function of (A) the minimum neck width and (B) the surface-to-volume (S/V) ratio. Plot legends denote the pitch size of PnCs. The black dashed line in (A) represents the thermal conductivity of bare amorphous Si3N4 thin films.
Fig. 3 Effective thermal conductivity of amorphous Si3N4 PnCs. Comparison between the measured and the simulated effective thermal conductivity of amorphous Si3N4 PnCs plotted as a function of the neck width. Plot legends denote the pitch size of PnCs, where Exp. and Cal. denote Experiment and Calculation.
Fig. 4 Calculated thermal properties of amorphous Si3N4. (A) Comparison of the effective MFP of propagons and diffusons for bulk a-Si3N4 and a-Si3N4 phononic materials, taking the sample with a pitch size P of 200 nm and a hole diameter D of 175 nm as an example. (B) Comparison of thermal conductivity κ spectra for bulk a-Si3N4 and a-Si3N4 phononic materials, taking the sample with P = 200 nm and D = 175 nm as an example. (C) and (D) are the calculated thermal conductivity contribution from diffusons (κD) and propagons (κP) for all samples as a function of neck width.
- Table 1 Lists of amorphous Si3N4 PnC structures with a thickness of 70 nm.
Pitch (nm) Porosity Diameter (nm) Neck width
(nm)36 0.44 25 11 60 0.30 35 25 60 0.36 38 22 60 0.39 39 21 100 0.44 70 30 100 0.50 74 26 100 0.53 76 24 100 0.59 81 19 200 0.39 132 68 200 0.47 144 56 200 0.54 154 46 200 0.58 160 40 200 0.69 175 25 400 0.39 262 138 400 0.46 285 115 400 0.57 317 83 800 0.36 506 294 800 0.44 557 243 800 0.50 594 206 1600 0.31 935 665 1600 0.36 1013 587 1600 0.40 1063 537
Supplementary Materials
Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/39/eabc0075/DC1
Additional Files
Supplementary Materials
Ultimate suppression of thermal transport in amorphous silicon nitride by phononic nanostructure
Naoki Tambo, Yuxuan Liao, Chun Zhou, Elizabeth Michiko Ashley, Kouhei Takahashi, Paul F. Nealey, Yasuyuki Naito, Junichiro Shiomi
This PDF file includes:
- Sections S1 to S3
- Figs. S1 to S5
- Table S1
- References
Files in this Data Supplement:
