Stable field emission with low threshold field from amorphous carbon films due to layer-by-layer hydrogen plasma annealing

Abstract

The layer-by-layer hydrogen plasma treatment method, alternatively repeating the process of nanometer thickness film deposition and hydrogen plasma chemical annealing, was applied to fabricate amorphous carbon (a-C) films. It was shown that hydrogen plasma treatment reduced the size of sp2 clusters and resulted in the increase of the optical band gap. Consequently, a stable vacuum electron emission with a low threshold field was achieved from layer-by-layer hydrogen plasma annealed a-C films compared with that from conventionally deposited samples. The threshold electric field was as low as 2 V/μm. The improvement of field emission characteristics could be attributed to the large field enhancement effect due to the inhomogeneous distribution of nanometer scale sp2 clusters.