Effect of Ar+, N-2(+), He+ and H-2(+) bombardment on the composition and structure of CNx layers

Amorphous CNx layers of high N-content, close to CN stoichiometry, were pre pared by reacting a graphite target with nitrogen in DC plasma. The CN laye rs were subjected to 2 keV Ar+, He+, H-2(+): and also to 2 and 4 keV N-2(+) : bombardment at fluences in the range of 10(15)-10(17) ions/cm(2). Changes in chemical composition and structure were followed by X-ray photoelectron and Infra red spectroscopy. The broad asymmetric C1s and N1s line shapes m anifested several bonding states assignable by IR mainly to single and conj ugated C=N and also a small amount of C=N species. Ion bombardment caused p referential removal of N with simultaneous formation of different C-C bonds . Conjugated C=N bonds seemed to be more stable at ion bombardment than the other C-N type bonds. No evidence of appreciable transformation to the fav ourable sp(3) C-N species could be detected. (C) 1999 Elsevier Science B.V. All rights reserved.