Universal phonon mean free path spectra in crystalline semiconductors at high temperature

• Published in: Scientific reports Vol. 3; no. 1; p. 2963
• Main Authors: Freedman, Justin P., Leach, Jacob H., Preble, Edward A., Sitar, Zlatko, Davis, Robert F., Malen, Jonathan A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16.10.2013; Nature Publishing Group
• Subjects: 639/166/988; 639/301/1005/1007; 639/301/1019/1020/1089; 639/301/299/2736; Heat conductivity; High temperature; Humanities and Social Sciences; multidisciplinary; Science; Semiconductors; Surface temperature; Temperature effects; Thermal conductivity
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep02963

Thermal conductivity in non-metallic crystalline materials results from cumulative contributions of phonons that have a broad range of mean free paths. Here we use high frequency surface temperature modulation that generates non-diffusive phonon transport to probe the phonon mean free path spectra of GaAs, GaN, AlN and 4H-SiC at temperatures near 80 K, 150 K, 300 K and 400 K. We find that phonons with MFPs greater than 230 ± 120 nm, 1000 ± 200 nm, 2500 ± 800 nm and 4200 ± 850 nm contribute 50% of the bulk thermal conductivity of GaAs, GaN, AlN and 4H-SiC near room temperature. By non-dimensionalizing the data based on Umklapp scattering rates of phonons, we identified a universal phonon mean free path spectrum in small unit cell crystalline semiconductors at high temperature.