Separation of epitaxial thin films on a growth substrate and transfer onto other materials for functional heterostructures have boosted the transformative impact on science and technology. However, this scheme has proved challenging in thin-film thermoelectrics but promises a vast range of applications beyond the limited device configurations of bulk thermoelectrics. Here, the high-quality Bi0.5Sb1.5Te3 (BST) epitaxial thin film on a sapphire substrate grown by spontaneous van der Waals epitaxy (vdWE) is exfoliated and transferred onto versatile materials, creating high-performance thermoelectric membranes. Unprecedented millimeter-size vdWE BST membranes are produced by etching a pseudomorphic Te monolayer on the surface of a sapphire substrate in dilute HF solution. The intact exfoliation and direct transfer for vdWE BST membranes maintain the high-quality crystallinity, resulting in the remarkable zT value (∼0.9 at 300 K). These results represent the realization of long-pursued but undemonstrated high-performance thin-film thermoelectrics, paving the way for the design and fabrication of arbitrarily shaped thermoelectric devices.
Bibliographical noteFunding Information:
This work was supported by the Samsung Research Funding & Incubation Center of Samsung Electronics under Project Number SRFC-MA1701-05 and by the Institute for Basic Science (IBS-R011-D1).
© Authors 2021
All Science Journal Classification (ASJC) codes
- Chemistry (miscellaneous)
- Renewable Energy, Sustainability and the Environment
- Fuel Technology
- Energy Engineering and Power Technology
- Materials Chemistry