Microstructure, optical and electrical properties of nitrogen doped sp 2-rich a-C thin films grown by facing-target magnetron sputtering
Abstract
N atoms were incorporated into sp 2-rich a-C networks using DC facing-target reactive sputtering at various N 2 fraction ( P) and their structure and opto-electrical properties were investigated systematically. As P increases, the fraction of CN bonded carbons (or the N content) increases primarily at the expense of the CC bonded carbons and then reaches its saturated value at P > 40%. The incorporated N preferentially forms different kinds of non-aromatic CN phase, leading to more localization of π electrons and the loss of the connectivity of nanographite fragments in the films, which is different from the case in N-doped sp 3-rich a-CN x films. Hence, with increasing P, the a-C(:N) film converts from a semiconductor with a narrower optical band gap to an insulator-like material with a wider gap. Additionally, the variation of optical constants ( n and k) and spin defects are related to the enhancement of the non-aromatic CN phase.
- Publication:
-
Applied Surface Science
- Pub Date:
- September 2009
- DOI:
- 10.1016/j.apsusc.2009.07.077
- Bibcode:
- 2009ApSS..255.9498W