Effect of Ba/Ag Ratio on the Structural, Electrical, and Thermoelectric Properties of Ba₂AgSi₃ Thin Films

Ba₂AgSi₃ thin films were grown on Si(111) substrates using molecular beam epitaxy, and the effect of the Ba/Ag atomic ratio on the crystallinity and thermoelectric properties of the films was investigated. The results revealed that the properties changed significantly with the Ba/Ag atomic ratio. Notably, for films with a Ba/Ag ratio close to stoichiometry (Ba/Ag = 2), X-ray diffraction pattern analysis confirmed a distinct c-axis orientation, and epitaxial growth was demonstrated by reflection high-energy electron diffraction. Among the grown samples, the p-type film with Ba/Ag = 2.00 exhibited the most outstanding performance in both crystallinity and thermoelectric properties. Near room temperature (approximately 311 K), this film achieved a low thermal conductivity of 1.53 W m^-1 K^-1 and a high power factor of 470 μW m^-1 K^-2, resulting in a dimensionless figure of merit ZT of approximately 0.1. This performance is favorable for an undoped thin-film material operating near room temperature, suggesting that Ba₂AgSi₃ is a highly promising candidate for room-temperature thermoelectric applications.