Epitaxial growth of Ag on Ag-doped NaCl

Abstract

NaCl crystals doped with AgSO₄ have been grown in the laboratory and pure silver films of different thicknesses have been grown on the cleavages of doped and undoped crystals in a vacuum of the order of 10^-5 torr at room temperature by thermal evaporation. The films have been examined in an electron microscope and the nucleation and growth processes have been studied and compared. It is observed that: (i) preferential nucleation occurs on doped cleavages whereas uniform nucleation occurs on the undoped cleavages; (ii) coalescence of nuclei takes place earlier in films grown on doped substrates than on undoped ones; and (iii) films on doped substrates grow epitaxially with (100) orientation. The implications are discussed.