【Epitaxy Papers】Size effects and temperature dependence in the thermal conductivity of γ-Ga₂O₃ films

      Researchers from the Carnegie Mellon University have published a dissertation titled "Size effects and temperature dependence in the thermal conductivity of γ-Ga₂O₃ films" in Applied Physics Letters.

Abstract

      The thermal conductivities of (100) γ-Ga₂O₃ films deposited on (100) MgAl₂O₄ substrates with various thicknesses were measured using frequency-domain thermoreflectance. The measured thermal conductivities of γ-Ga₂O₃ films are lower than the thermal conductivities of (⁠ -201) β-Ga₂O₃ films of comparable thickness, which suggests that γ-phase inclusions in the doped or alloyed β-phase may affect its thermal conductivity. The thermal conductivity of γ-Ga₂O₃ increases from 2.3(+0.9−0.5) to 3.5±0.7 W/m K for films with thicknesses of 75–404 nm, which demonstrates a prominent size effect on thermal conductivity. The thermal conductivity of γ-Ga₂O₃ also shows a slight increase as temperature increases from 293 to 400 K. This increase in thermal conductivity occurs when defect and boundary scattering suppress signatures of temperature-dependent Umklapp scattering. γ-Ga₂O₃ has a cation-defective spinel structure with at least two gallium vacancies in every unit cell, which are the likely source of defect scattering.

DOI：

https://doi.org/10.1063/5.0270256