The authors report a field emitter structure based on barium strontium oxide coated carbon nanotubes (CNTs). This emitter consists of a thin tungsten ribbon with CNTs on the surface, and a thin layer of low work function barium strontium oxide coating on the CNTs. CNTs were grown on the surface of the tungsten ribbon by plasma enhanced chemical vapor deposition, and the oxide coatings were prepared using magnetron sputtering. This oxide coated CNT emitter was designed to combine the benefits of the high field enhancement factor from CNTs and the low work function from the emissive oxide coating. The field emission properties of the emitters were characterized. A field enhancement factor of 478 and a work function of 1.9 eV were obtained for the oxide coated CNTs. As a result of the reduction of surface work function, the field emission from the oxide coated CNTs increased by a factor of 2-3 compared to the uncoated CNTs. At 4.4 V/mu m, the field emission current of 23.6 mu A was obtained from an emitting surface of 0.012 cm(2). (C) 2007 American Vacuum Society.