Suitability of low-work-function titanium nitride coated transfer mold field-emitter arrays for harsh environment applications

Abstract

Low-work-function titanium nitride (TiN) coated transfer mold field-emitter arrays (TiN-FEAs) were fabricated by the transfer metal mold method. This method has potential for realizing stable large-area aerospace nanodevices that are resistant to the harsh plasma atmospheres often experienced by electric propulsion engines in space. Another application is for production of vacuum nanoelectronic devices such as field-emission displays that are suitable for highly oxidizing atmospheres. TiN-FEAs have sharp tips with radii of 6.8 nm, and their work function is just 3.2 eV compared to approximately 5.0 eV for conventional emitter materials such as carbon nanotubes. The turn-on fields of TiN-FEAs are as low as 15.4 V/μm, and their anode-to-emitter distance is 10 μm. Field-emission characteristics of TiN-FEAs were evaluated in situ at a pressure as high as 10−3 Pa and by irradiation with oxygen radicals at 1015 cm−2 s−1, a flux several orders of magnitude higher than orbital satellites typically experience. As the treatment time increased, the turn-on fields of TiN-FEAs changed only slightly from 15.4 to 18.8 V/μm, with no observed change in the work function during the in situ oxygen radical treatment. In summary, the TiN-FEAs exhibited stable field-emission characteristics and a high level of resistance to harsh environments.