Preferential growth transformation of Bi0.5Sb1.5Te3 films induced by facile post-annealing process: Enhanced thermoelectric performance with layered structure

• Published in: Thin solid films 2014-04, Vol.556, p.270-276
• Main Authors: Zhu, Wei, Deng, Yuan, Wang, Yao, Luo, Bingwei, Cao, Lili
• Format: Article
• Language: English
• Subjects: Bismuth antimony telluride; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Diffusion; interface formation; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Preferential growth; Solid surfaces and solid-solid interfaces; Sputtering; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Theory and models of film growth; Thermoelectric effects; Thermoelectric performance; Thermoelectric properties; Thin films
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2014.02.041

Preferential growth transformation from (015) plane to (00l) plane of the bismuth antimony tellurium (Bi0.5Sb1.5Te3) film has been achieved through a facile post-annealing process with enhanced thermoelectric performance. The Bi0.5Sb1.5Te3 film with preferential growth of (015) crystal plane was obtained via dc magnetron sputtering, and the Stranski–Krastanov model has been used to explain its growth mechanism. Preferential growth transformation from (015) plane to (00l) plane occurred after a post-annealing process. The driving force of this phenomenon is the natural tendency to reduce the total interfacial energy of the system, and the migration and coalescence of atoms along the in-plane direction form the layered structure. Moreover, the carrier concentration of Bi0.5Sb1.5Te3 films is optimized to ~019/cm3 in the film with preferential growth of (00l) plan. Hence, a synchronous increase of electrical conductivity and Seebeck coefficient is obtained due to the greatly enhanced carrier mobility and optimized carrier concentration. Therefore, the Bi0.5Sb1.5Te3 film with the preferential growth of (00l) plane possesses power factor of 48.2μW/cmK2 which is three times higher than that of the film with the preferential growth of (015) plane. Our study has provided a facile strategy to induce preferential growth transformation in Bi0.5Sb1.5Te3 films and meanwhile largely enhanced the thermoelectric performance. •Preferential growth transformation is obtained by a facile post-annealing process.•Preferential growth and transformation mechanisms have been discussed.•Electrical conductivity and Seebeck coefficient are enhanced synchronously.•The largest power factor of 48.2μW/cmK2 in Bi0.5Sb1.5Te3 films is achieved.•Our study provides an effective way to improve the thermoelectric performance.