Photoconductivity of DLC film deposited by pulsed discharge plasma CVD

• Published in: Diamond and related materials Vol. 17; no. 4; pp. 676 - 679
• Main Authors: Kawai, S., Shinagawa, T., Noda, M., Umeno, M.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01-04-2008; Elsevier
• Subjects: Band gap; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; DLC; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; ESR; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Ion and electron beam-assisted deposition; ion plating; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Photoconduction and photovoltaic effects; photodielectric effects; Photoconductivity; Physics; Pulsed discharge plasma CVD; Specific materials; Pulsed discharge plasma CVD; DLC; Band gap; Photoconductivity; ESR; Methane; Electronic properties; Phase transformations; Diamond-like carbon; Spin density; Raman spectroscopy; Thin films; CVD; Energy gap; Electronic structure; Pulsed discharge; Dark current; PECVD; Electron paramagnetic resonance; Electron density; Plasma deposition; Graphitization
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/j.diamond.2008.01.085

DLC films were deposited by a new pulsed DC discharge plasma chemical vapour deposition (CVD) using hydrogen and methane gas mixture. When methane concentration (Cm) i.e. CH
4/(H
2
+
CH
4) was increased from 3 to 40%, the graphitization of the carbon film increases as evident from Raman study. When Cm was increased to 30%, DLC film shows photoconducting property. The white light photoconductivity (
S
=
I
l/
I
d, where
I
l is light current and
I
d is dark current) measured with solar simulator under AM 1.5 condition was approximately 20 at room temperature. The photoconductivity was not clear when Cm was lower than 20%. ESR measurements also show that the electron spin density was slightly decreased with decreasing concentration of methane. Thus we can conclude here that at higher concentrations of methane at 30%, Sp
2 content of the film increases and the DLC film becomes photoconducting.