Plasma-immersion ion-processed boron-doped diamond-like carbon films

Abstract

Boron-doped diamond-like carbon (DLC) was prepared using an inductive radio-frequency Ar + C2 H2 + B2 H6 plasma-immersion ion-processing (PIIP) technique. The novel results show that B incorporation reduces the stress and that low-energy Ar-ion impingement suppresses the increase of the amount of hydrogen in the B-doped DLC film. An optimal combination of higher hardness, 24.6 - 28 GPa, and reduced stress was reached in DLC film doped with 4 to 10 at.% B. An increase in the sp3 carbon and sp3 CH bonding in the DLC films was found with B doping and was correlated with the enhancement of the properties.

Synthesis and characterization of boron incorporated diamond-like carbon thin films

“…The actual B content to form B-C bonding is lower for B-DLC-1 than other samples with lower total B content. As we have discussed in Section 4.3, the increase of sp 3 bonded C by B doping is probably due to the formation of B-C bonding (He et al, 2000). Therefore it is reasonable that the sp 3 C bonding content of B-DLC-2 and 3 is higher than B-DLC-1.…”

“…The increase of sp is stronger than C-C bond (332 kJ/mol) and C-H bond (414 kJ/mol) is stronger than B-H bond (389 kJ/mol) (He et al, 2000).…”

“…B incorporation to hydrogenated DLC can reduce film stress and promote the formation of sp 3 carbon bonding in the films, thus enhance the film hardness and film adhesion strength (He et al, 2000;Ahmad et al, 2007). Similarly, B incorporation in low concentrations to hydrogen free DLC can also result in an increase of sp 3 carbon bonding in the films (Monteiro, 2001).…”

“…He et al reported that B incorporation to hydrogenated DLC up to 10 at. % by radio frequency plasma-immersion ion deposition leads to an increase of sp 3 carbon bonding in the films (He et al, 2000). Monteiro…”

“…boron (B), silicon (Si), nitrogen (N), fluorine (F), and their combinations (Erdemir et al, 2006). B incorporation to DLC has been receiving increasing research interest because B incorporated DLC (B-DLC) thin films have been found to exhibit increased thermal stability (Monteiro, 2001), improved electron field emission (Cheng et al, 1999), increased hardness and reduced film stress (He et al, 2000) with great potential for electronic and mechanical applications. The techniques currently used to synthesize B-DLC films include magnetron sputtering, mass-separated ion beam deposition, plasma-enhanced chemical vapor deposition (CVD), and pulsed laser deposition.…”