2018 article

Thermal conductivity of bulk and thin film beta-Ga2O3 measured by the 3 omega technique


co-author countries: Sweden 🇸🇪 United States of America 🇺🇸
author keywords: gallium oxide; thermal conductivity; thin films
Source: Web Of Science
Added: December 31, 2018

Thermal conductivity of undoped and Sn-doped &beta;-Ga<sub>2</sub>O<sub>3</sub> bulk and single-crystalline thin films have been measured by the 3&omega; technique. The bulk samples were grown by edge-defined film-field growth (EFG) method, while the thin films were grown on c-plane sapphire by pulsed-laser deposition (PLD). All samples were with (-201) surface orientation. Thermal conductivity of bulk samples was calculated along the in-plane and cross-plane crystallographic directions, yielding a maximum value of ~ 29 W/m-K in the [010] direction at room temperature. A slight thermal conductivity decrease was observed in the Sn-doped bulk samples, which was attributed to enhanced phonon-impurity scattering. The differential 3ω method was used for &beta;-Ga<sub>2</sub>O<sub>3</sub> thin film samples due to the small film thickness. Results show that both undoped and Sndoped films have a much lower thermal conductivity than that of the bulk samples, which is consistent with previous reports in the literature showing a linear relationship between thermal conductivity and film thickness. Similarly to bulk samples, Sn-doped thin films have exhibited a thermal conductivity decrease. However, this decrease was found to be much greater in thin film samples, and increased with Sn doping concentration. A correlation between thermal conductivity and defect/dislocation density was made for the undoped thin films.