We studied the effect of bias aging on the field emission properties of selectively patterned carbon nanotube field emitter arrays (CNT) grown using the resist-assisted patterning process. After electrical aging using an electric field of 6.87 V/mu m for 40 h, it was observed that the electron emission properties and uniformity were remarkably improved. X-ray photoelectron spectroscopy spectra show a shift of 0.2 eV in the O-1s peak and the concentration of oxygen is reduced. Also, transmission electron microscopy measurements showed that Ni catalyst was removed from CNT tips after aging. Therefore, after electrical aging, we obtained enhanced and stable electron emission over a wide current range. (c) 2008 American Vacuum Society.