The Phases and Morphology of Bi₂Te₃ Films Prepared by Electrodeposition

Abstract

Thermoelectric materials Bi₂Te₃ films were synthesized by electrodeposition using Bi₂O₃ and TeO₂ as raw materials. The effects of electrodeposition technologies on formation of Bi₂Te₃ phase were investigated under different deposition conditions. The phases of obtained products were analyzed by X-ray diffraction (XRD) and the size and morphology were observed by scanning electron microscope (SEM). Experimental results show that, when the deposition potential increases from 0.7 V to 0.8 V, the Bi₂Te₃ phase can be gotten in the product film with good crystallinity while it increases up to −0.9 V particle shedding phenomenon occurred; The film deposited by Bi-Te ratio 1:5 has good crystallinity with the highest XRD intensity and sharp peaks by comparing different Bi-Te ion ratios. With the deposition time increasing, the XRD intensity becomes higher for Bi₂Te₃ phase in the product films obtained by depositing 4 min, 10 min to 15 min while lower for the SnO₂ layer on the substrates. The product film obtained at 50°C has the highest crystallinity in the samples obtained at 30°C, 40°C and 50°C. Lactic acid was the best additive for improving the quality of product films. Uniform and dense Bi₂Te₃ film with good crystallinity and particles size of 200 ∼ 300 nm can be obtained under the deposition conditions of 50°C, −0.8 V, 15 min and Bi-Te iron ratio 1:5.

Keywords:

• Thermoelectric materials
• Bi₂Te₃
• electrodeposition
• deposition potential
• phase formation