Phosphorus doping of diamond-like carbon films by radio frequency CVD-cum-evaporation technique

Diamond-like carbon (DLC) films have been deposited by cracking methane gas in radio frequency plasma. Phosphorus was incorporated in DLC films by simultaneously evaporating phosphorus during the synthesis of DLC with methane gas by using capacitatively coupled plasma chemical vapour deposition (CVD...

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Bibliographic Details
Published in:Diamond and related materials 2018-02, Vol.82, p.70-78
Main Authors: Dey, Rajkumar, Dolai, Sukdev, Hussain, Shamima, Bhar, Radhaballav, Pal, Arun Kumar
Format: Article
Language:English
Subjects:
Band gap
Carbon
Carrier density
Chemical synthesis
Chemical vapor deposition
Diamond-like carbon films
DLC
Electrical resistivity
Methane
Organic chemistry
P-doping
Phosphorus
Raman
X ray photoelectron spectroscopy
XPS
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Summary:Diamond-like carbon (DLC) films have been deposited by cracking methane gas in radio frequency plasma. Phosphorus was incorporated in DLC films by simultaneously evaporating phosphorus during the synthesis of DLC with methane gas by using capacitatively coupled plasma chemical vapour deposition (CVD) technique. The films were characterized by FESEM, XRD, XPS and Raman studies. The band gap of the pristine DLC films was found to be ~2.61eV and it decreased from 2.61eV to 2.31eV with increased incorporation of P in the DLC films. Raman studies indicated the presence of two broad peaks located at ~1360–1396cm−1 (D-line) and ~1542–1548cm−1 (G-line). The peak positions of the D-lines shifted in towards lower wave number with increased incorporation of phosphorus in them. This indicated that the DLC films became sp2 rich with increased incorporation of phosphorus. Electrical resistivity measurements have been carried out. The films were n-type as indicated by hot-probe technique. The values of electrical resistivity of the undoped and doped DLC films were 2.0×102Ω-cm and 0.7×102Ω-cm, respectively. Value of carrier concentrations (Nd) obtained were 2.5×1015cm−3 and 2.2×1016cm−3 for undoped and phosphorus doped DLC film with 3.4 at.% P in DLC, respectively. [Display omitted] •Phosphorous doping of DLC films is successfully demonstrated by CVD technique.•XRD of pristine DLC film indicated amorphous character showing humps for carbon.•The films became sp2 rich with increased phosphorous incorporation.
ISSN:0925-9635
1879-0062
DOI:10.1016/j.diamond.2018.01.002