Formation of a ZnSe:? heterostructure by air annealing ZnSe-In thin film
A thin film of indium approximately 10 nm thick was deposited by thermal evaporation onto a chemically deposited ZnSe thin film of thickness . Annealing the ZnSe-In films in air at 250 to for 15 min resulted in the formation of a -O heterostructure. The layer was approximately 10 nm thick with an average grain diameter of 20 nm. A sheet resistance of was observed over the film surface which is attributed to a non-stoichiometric film formed on the surface, with an n-type conductivity of . Annealing at or for a longer duration at could reduce this conductivity through improvement in the stoichiometry. The optical transmittance of the film for the visible and near-infrared region was . The underlying ZnSe film showed a direct bandgap of 2.7-2.75 eV. Etching in a dilute HCl solution removed the film and revealed a near-intrinsic ZnSe film, showing electrical properties similar to those of the ZnSe films annealed at the same temperature, with sheet resistance . Applications of the heterostructure to the fabrication of photonic devices are suggested.