Morphological Evolution of Te and Bi2Te3 Microstructures during Galvanic Displacement of Electrodeposited Co Thin Films

Co thin films with different crystalline structures including preferred orientation and grain size were electrodeposited from electrolytes containing an additive N-Dimethyldithiocarbamic acid ester, sodium salt, (DPS). Subsequently, the Co electrodeposits were converted to Te and Bi2Te3 via galvanic displacement reaction (GDR) processes. The morphologies of the produced Te and Bi2Te3 exhibited granular structures including whiskers and dendrites. Structural analyses showed that the microstructures strongly depended on the crystalline structure of the original Co thin films, which were also affected by the concentration of DPS. The formation mechanism of the Te whiskers and Bi2Te3 dendrites were elucidated by various analyses.