Interface-controlled electrical and thermal transport in Ag-decorated β-Ga₂O₃ nanostructures

Nanostructured oxide semiconductors provide a versatile platform for tailoring coupled electrical and thermal transport through interface engineering. In this work, pristine β-Ga₂O₃ and Ag-decorated β-Ga₂O₃ nanocomposites were synthesized via a hydrothermal route followed by thermal annealing and spark plasma sintering. Structural, microstructural, and compositional analyses confirmed the formation of phase-pure monoclinic β-Ga₂O₃ with uniformly dispersed Ag nanoparticles, resulting in well-defined Ag-β-Ga₂O₃ heterointerfaces. Hall-effect measurements revealed that Ag incorporation increased the carrier concentration from 7.97 × 10¹⁷ to 2.86 × 10¹⁸ cm^-3 and the carrier mobility from 37.95 to 43.61 cm² V^-1 s^-1, leading to enhanced electrical conductivity. The Ag-β-Ga₂O₃ interfaces facilitate carrier transport through interfacial barrier modulation while maintaining favorable thermopower, resulting in an enhanced power factor. Thermal conductivity is simultaneously reduced due to enhanced phonon scattering at grain boundaries and Ag-oxide interfaces arising from acoustic mismatch. Consequently, the thermoelectric figure of merit (ZT) increases from 0.25 for pristine β-Ga₂O₃ to 0.33 for Ag-decorated β-Ga₂O₃ at 873 K. These results demonstrate that Ag-induced interface engineering is an effective strategy for simultaneously optimizing electrical and thermal transport and highlight the potential of β-Ga₂O₃-based nanocomposites for high-temperature thermoelectric applications.