Periodic Modulation of Sb Stoichiometry in Bi2Te3/Bi2–xSbxTe3 Multilayers Using Pulsed Electrodeposition

Thin film Bi2Te3/Sb2Te3 multilayers are thought to possess a high thermoelectric figure of merit. Our work describes how multilayers can be fabricated using electrodeposition, an inexpensive and scalable synthesis route. We address the challenge of simultaneously maintaining satisfactory stoichiometry, crystallinity, and scalability for this complex structure. We have synthesized Bi2Te3/Bi2–xSbxTe3 multilayers by pulsed potentiostatic electrodeposition from a single bath of an acidic aqueous electrolyte over a cm2 area. Cyclic voltammetry studies of the Bi/Sb/Te bath revealed two distinct potentials that resulted in the deposition of Bi2Te3 and (Bi1–xSbx)2Te3. Scanning transmission electron microscopy for our multilayers shows layer periodicity in the 10–30 nm range. Grazing incidence X-ray diffraction measurements show that the multilayer films possessed a {015} texture across the entire cm2 substrate. Proper choice of pulse parameters can significantly improve the stoichiometry, crystallography, and mic...