Top surface modification of carbon film on its structure, morphology and electrical resistivity using electron-ion hybrid irradiation in ECR plasma

A two-step electron-ion hybrid irradiation process in electron cyclotron resonance (ECR) plasma was proposed as a flexible method to obtain carbon film with low roughness and electrical conductive surface. By the combination of either electron irradiation or ion irradiation during and after film deposition, two modes of hybrid irradiation were realized: In i-e hybrid mode, smooth amorphous carbon film was firstly deposited under ion irradiation, and its electrical resistivity was reduced from 1.4 to 0.12 Ω·cm− 1 after 5-min electron irradiation. In e-i hybrid mode, conductive graphene nanocrystallited film was firstly deposited, and its surface Ra roughness was decreased from 15.7 to 0.063 nm after 5-min ion irradiation. The top surface structural transition under electron irradiation in the i-e mode were demonstrated by transmission electron microscopy (TEM), Raman spectra, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), and the effective depth of electron irradiation on carbon film surface were discussed. This study provided a practical route to the massive production of ultra-smooth carbon films with novel nanostructure and outstanding physical properties for potential applications in nano-machinery and nano-devices. The hybrid irradiation method also expanded the way of plasma utilization in the fields of film deposition and surface modification, and will inspire various new films and coatings with improved top surfaces.