Patterning Bi2Se3 single-crystalline thin films on Si(111) substrates using strong oxidizing acids

Acidic potassium dichromate solutions (K2Cr2O7-H2SO4 and K2Cr2O7-HCl) are applied for patterning single crystalline Bi2Se3 thin films on Si(111) substrates. In solutions with appropriate component proportions, vertical walls and mesa-shaped structures on the etching profiles of (001) Bi2Se3 films can be achieved. Stoichiometric etching behavior is noted for Bi2Se3 in K2Cr2O7-H2SO4 etchant, while incongruently dissolution of Bi2Se3 in K2Cr2O7-HCl is observed which leaves a Se deficient layer on the etched film surface. The chemical reaction kinetics of Bi2Se3 in the two different etchants are also discussed.