Large scale Al-containing amorphous carbon (a-C:Al) nanotip arrays with uniform size and high density were obtained through filtered cathodic arc plasma (FCAP) technique via a specially widened anodic aluminum oxide (AAO) pore arrays as templates. The nanotip is about 100 nm in diameter at the bottom and 120 nm in height with density of 1010 cm−2. It was found that the sp3/(sp3 + sp2) ratio were 60.2%, 64.0%, 65.1% and 67.2% for Al content of 0.94 at%, 3.85 at%, 5.33 at% and 6.38 at%, respectively. The threshold field decreased to 0.32 V/m at 10 mA/cm2 and the maximum emission current density increased to 72 mA/cm2 at Al content of 6.38 at%. This kind of material will play a significant role in cold-cathode field emission display area.

Nanotip arrays of amorphous carbon with embedded hexagonal diamond nanoparticles were prepared at room temperature for use as excellent field emitters by a unique combination of anodic aluminum oxide (AAO) template and filtered cathodic arc plasma (FCAP) technology. In order to avoid nanopore array formation on the AAO surface, an effective multi-step treatment employing anodization and pore-widening processes alternately was adopted. The nanotips were about 100 nm in width at the bottom and 150 nm in height with density up to 1010 cm−2. Transmission electron microscopy investigation indicates that many nanoparticles with diameters of about 10 nm were embedded in the amorphous carbon matrix, which was proved to be hexagonal diamond phase by Raman spectrum and selected-area electron diffraction. There is no previous literature report on the field emission properties of hexagonal diamond and its preparation at room temperature under high-vacuum condition. The nanotip arrays with hexagonal diamond phase exhibit a low turn-on field of 0.5 V/μm and a threshold field of 3.5 V/μm at 10 mA/cm2. It is believed that the existence of hexagonal diamond phase has improved the field emission properties.