Extremely low thermal conductivity of β−Ga2O3 with porous structure

• Published in: Journal of applied physics Vol. 130; no. 19
• Main Authors: Wu, H. J., Ning, S. T., Qi, N., Ren, F., Chen, Z. Q., Su, X. L., Tang, X. F.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 21.11.2021
• Subjects: Applied physics; Carrier mobility; Gallium oxides; Heat conductivity; Heat transfer; High temperature; Low temperature; Plasma sintering; Room temperature; Sintering (powder metallurgy); Spark plasma sintering; Sucrose; Thermal conductivity; Thermal stability; Thermoelectric materials
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/5.0069338

Due to the ultrawide bandgap (4.9 eV), high carrier mobility (300  cm 2 V − 1 s − 1), and high thermal stability, β − Ga 2 O 3 can be a potential candidate for high-temperature thermoelectric materials. However, the intrinsically high thermal conductivity may hinder its application for thermoelectric conversion. In this work, porous β − Ga 2 O 3 was prepared by the solvothermal method together with spark plasma sintering technology. Positron lifetime measurement and N 2 adsorption confirm the introduction of pores by adding sucrose in the sample preparation. The sucrose-derived β − Ga 2 O 3 sintered at a relatively low temperature of 600  °C remains highly porous, which results in an extremely low thermal conductivity of 0.45 W  m − 1 K − 1 at room temperature, and it further decreases to 0.29 W  m − 1 K − 1 at 600  °C. This is the lowest thermal conductivity for β − Ga 2 O 3 reported so far. Our work provides an avenue to reduce the thermal conductivity for β − Ga 2 O 3 and is believed to be widely applicable to many other thermoelectric materials.