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

Abstract

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.