Characterization of boron- and phosphorous-incorporated tetrahedral amorphous carbon films deposited by the filtered cathodic vacuum arc process

This paper reports the X-ray photoelectron spectroscopy (XPS), X-ray-induced Auger electron spectroscopy (XAES), and Raman studies of boron- and phosphorous-incorporated tetrahedral amorphous carbon (ta-C) films deposited by the filtered cathodic vacuum arc process. A systematic study of the influence of varying boron (B) and phosphorous (P) content on the properties of the as-grown ta-C films deposited at high negative substrate bias (-300 V) is reported by analyzing the C 1s, B 1s, and P 1s core levels using photoelectron spectroscopy. The sp³ and sp² contents in the films were determined by measuring the width of the X-ray-induced Auger peaks. B incorporation in ta-C films up to 2.0 at.% increases the sp² content and decreases the sp³ content by 3.6%, whereas P incorporation up to 2.0 at.% results in an increase of sp² content and decrease of sp³ content by ̃30%. The valence band spectra show changes in the Fermi level as B and P are incorporated into the ta-C films. The characteristic Raman spectra c onfirm the high sp³ content in the deposited films. Thus, the study demonstrates, in the case of high negative substrate bias films, that a pronounced decrease in sp³fraction or the diamond-like nature of the ta-C films occurs upon P incorporation in comparison to that upon B incorporation.