Direct observation of thickness and foreign interlayer driven abrupt structural transformation in ultrathin carbon and hybrid silicon nitride/carbon films. (May 2017)

• Record Type: Journal Article
• Authors: Dwivedi, Neeraj; Yeo, Reuben J.; Zhang, Zheng; Dhand, Chetna; Tripathy, Sudhiranjan; Bhatia, Charanjit S.
• Is Part Of: Carbon. Volume 115(2017)
• Page Start: 701
• Page End: 719
• Publication Date: 2017-05
• Subjects: Carbon -- Periodicals; Carbone -- Périodiques; Koolstof; Toepassingen; Electronic journals; 546.681
• DOI: 10.1016/j.carbon.2017.01.061
• Languages: English
• ISSNs: 0008-6223

Abstract

Abstract: Despite its predominant role in controlling the functional properties, a longstanding concern in the research of ultrathin amorphous carbon and its hybrid materials is the inadequate understanding of their structural properties, especially on ceramic substrates. This constitutes a barrier for many technological developments. Here we comprehensively examine the structural properties of ultrathin carbon and hybrid silicon nitride/carbon (SiNx /C) films on a ceramic substrate. We observe large Raman G peak shifting, colossal enhancement (small but visible increase) in the sp 3 carbon bonding of filtered cathodic vacuum arc-processed (sputter-processed) carbon films with increasing film thickness from 0.5 to 20 nm. We construct a novel three-phase model to explain the results which are also supported by core-level photoemission spectroscopy. We notice a huge change in sp 3 growth dynamics for 1–7 nm thick films which is found to be significantly larger for filtered cathodic vacuum arc-processed (∼7%/nm) than sputter-processed (∼1.1%/nm) carbon films, based on Raman spectroscopy. We also observe strong SiNx layer(s)-driven shifting of the Raman G peak, reduction of the ID /IG ratio and tuning of the sp 3 bonding in SiNx /C bilayer and multilayer films. These results are very important for fundamental science and ultrathin carbon-based technologies. Graphical abstract: A thickness driven tuning of sp 3 bonding was observed in ultrathin carbon films. The huge change in sp 3 growth dynamics for 1–7 nm thick films was noticed which calculated to be significantly larger for filtered cathodic vacuum arc (FCVA)-processed (∼7%/nm) than sputter-processed (∼1.1%/nm) carbon films, based on Raman spectroscopy.