Carbon-in-Al₄C₃ Nanowire Superstructures for Field Emitters

As a kind of ionic (or salt-like) carbide, for Al(4)C(3), hardly any active functions have been found except for structure material purposes. However, considering the unique characteristic features of its crystal structure, we think Al(4)C(3) in fact might have huge potential for exhibiting active functionality on field-emission applications. Herein, we report the feasibility to approach such emitters by creating Al(4)C(3)-based nanowire superstructures. The conductive amorphous carbon (a-C) nanolayers are embedded quasi-periodically in Al(4)C(3) nanowire and generate essential electrical contact to the insulating Al(4)C(3). The superstructures acting as cold electron emitters display excellent field emission performance with the turn-on field as low as 0.65-1.3 V/μm and the threshold field down to 2.1-2.6 V/μm. We speculate that the emission characteristics, which are ever better than carbon nanotubes, are attributed to the unique crystal structure of Al(4)C(3) and the enhanced electrons transport in the nanowires due to the existence of a-C nanolayers. Such emitters are technologically useful, because they can be easily fabricated on large substrates, and the synthesis process is simple and broadly applicable. The findings conceptually provide new opportunities for the application of Al(4)C(3) ceramic material in vacuum microelectronic devices.