Epitaxial growth of high-quality Mg3Sb2 thin films on annealed c-plane Al2O3 substrates and their thermoelectric properties

Abstract

High-quality epitaxial Mg _3 Sb _2 thin films are promising thermoelectric materials to enable practical applications of compact and environmentally friendly thermoelectric conversion at RT. In this study, high-quality single-crystal Mg _3 Sb _2 with high c-plane orientation was epitaxially grown directly on annealed c-Al _2 O _3 substrates without passive layers. These thin films exhibited about three times higher thermoelectric power factor than any previously reported values due to high carrier mobility. The ultra-smooth surface of the annealed c-Al _2 O _3 substrate facilitated the formation of high-quality Mg _3 Sb _2 thin films without passive layers or polycrystalline interfaces that could be carrier scatters.

Keywords

• epitaxial growth
• Mg3Sb2
• Zintl phase compound
• thermoelectric material
• Al2O3 substrate