  We report that the surface conductivity of Na$_{2}$IrO$_3$ crystal is
extremely tunable by high energy Ar plasma etching and can be tuned from
insulating to metallic with increasing etching time. Temperature dependent
electrical transport for the metallic samples show signatures of first order
phase transitions which are consistent with charge or spin density wave like
phase transitions recently predicted theoretically. Additionally,
grazing-incidence small-angle x-ray scattering (GISAXS) reveal that the room
temperature surface structure of Na$_{2}$IrO$_3$ does not change after plasma
etching.
