Vapor cells and methods for making the same are presented, in which a cell cavity is completely filled with aqueous alkali metal azide solution and the solution is dried at a controlled evaporation rate to substantially maintain edge contact pinning at an interface with the cavity sidewall to promote preferential evaporation in the center and outward capillary flow from an unpinned air-fluid interface toward the sidewall to form crystallized alkali metal material at the sidewall while inhibiting drying of dispersed aqueous solution on a transparent cavity bottom to provide substantially unrestricted passage of light through the cavity for atomic clock and other applications.