Improvement in salt-water durability of Ag thin films deposited by magnetron sputtering using argon and nitrogen mixed gas

Abstract

Ag thin films were deposited by magnetron sputtering in a mixture of argon and nitrogen. The salt-water durability and reflectance of Ag thin films were investigated as a function of nitrogen gas flow ratio during sputter deposition. The reflectance of as-deposited Ag thin films decreased with increasing nitrogen gas flow ratio; however, the difference in visible-light reflectance between the Ag thin films deposited with and without nitrogen was less than 1%. The reflectance of Ag thin films that were deposited using pure argon significantly decreased after the films were soaked in salt water. In contrast, the salt-water durability of Ag thin films was improved when the nitrogen gas flow ratio was increased. X-ray diffraction and atomic force microscopy analyses revealed that the Ag thin films deposited in sufficient nitrogen exhibited smooth surfaces and small crystallite sizes. Hence, the agglomeration of Ag thin films was suppressed; as a consequence, the reflectance of Ag thin films deposited in nitrogen did not decrease to the same extent, despite being soaked in salt water.