Properties of boron and phosphorous incorporated tetrahedral amorphous carbon films grown using filtered cathodic vacuum arc process

摘要

This paper reports the electrical, mechanical, structural and field emission properties of as grown and also boron and phosphorous incorporated tetrahedral amorphous carbon (ta-C) films, deposited using a filtered cathodic vacuum arc process. The effect of varying boron and phosphorous content (up to 2.0 at.% in to ta-C) on the conductivity (σ_D), activation energy (ΔE_1), hardness, microstructure, emission threshold (E_(turn-ON)) and emission current density (J) at 12.5 V/μm of ta-C: B and ta-C: P films deposited at a high negative substrate bias of -300 V are reported. It is observed that both boron and phosphorous incorporation leads to a nearly an order increase in σ_D and corresponding decrease in ΔE_1 and a slight increase in hardness as compared to as grown ta-C films. In the case of field assisted electron emission, it is observed that E_(turn-ON) increases and J decreases. The changes are attributed to the changes in the sp~3/sp~2 ratio of the films due to boron and phosphorous incorporation. The effect of boron on ta-C is to give a p-type effect whereas the effect of phosphorous gives n-type doping effect.