Polymorphic carbon thin films

Research Activities:

The major activity is to synthesize graphene by filtered cathodic vacuum arc (FCVA) and microwave plasma enhanced chemical vapor deposition (MWPECVD) techniques. Other related works are as follows:

  • Synthesize graphene by filtered cathodic vacuum arc (FCVA) and microwave plasma enhanced chemical vapor deposition (MWPECVD) techniques.
  • Characterization of graphene and exploration of graphene based devices.
  • Deposition of (i) amorphous carbon (a-C) films by FCVA, (ii) a-C with embedded nanocrystallites by modified arc based techniques, (iii) boron and phosphorous doped micro and nano silicon and silicon carbide films by FCVA and (iv) nanodiamond and other nanocarbon structures by MWPECVD system.
  • We have the deposition facilities of FCVA and MWPECVD and characterization by field emission and Nano indentation.

Recent Highlights:

We have synthesized multilayered graphene from a-C films by using FCVA and graphene oxide by MWPECVD technique. The typical results of Raman, optical image, SEM and transmittance are presented.

(A) Results of FCVA deposited graphene


Raman spectra

Optical image

SEM micrograph

Transmittance spectra

(B) Results of MPECVD deposited graphene oxide


XRD spectra

Raman spectra

SEM micrograph

Transmittance spectra

Team:

Head:

Dr. O. S. Panwar, Chief Scientist                                      ospanwar@nplindia.org                               

Scientists & Technical Staff:

Dr. Sreekumar Chockalingam, Senior Scientist           sreekuc@nplindia.org
Mr. Jagdish Chand, Senior Technical Officer-II             chaudhjc@nplindia.org

Other Supporting Staff:

Mrs. Suman Bhardwaj, Senior Technician                     s_bhardwaj@nplindia.org
Mr. Ram Rajjan, Lab Assistant

Contact:

Dr. O. S. Panwar. Phone No: 011 45609175, 45608648, Email: ospanwar@nplindia.org

Major Facilities:

A. Deposition Systems:

Filtered Cathodic Vacuum Arc (FCVA)

A physical vapor deposition facility called the “Filtered cathodic vacuum arc” (FCVA) has been custom designed and indigenously developed in the National Physical Laboratory (NPL) (CSIR News Vol 56, No 9, 15 May 2006). The system consists of (a) water cooled cathode and anode, (b) S bend magnetic filter for the removal of macro particles and the neutrals and (c) 8 inch SS deposition chamber. The system has two turbo molecular pumps backed by the rotary pumps that enable to achieve a base pressure of ~ 1x10-6 mbar. DC power supplies energize the magnetic filter and a magnetic field of ~ 350 G is achieved inside the duct. A mechanical striker that uses a DC arc supply of 0-30 V and is capable of delivering ~ 200 A current initiates the arc. In this technique, film is deposited by condensation of highly ionized plasma on any substrate including low melting point plastic at room temperature. The process can be carried out in high vacuum or in low pressure gaseous environment and films can be formed of metals, ceramics, diamond like carbon, some semiconductors and superconductors. The system developed at NPL has been optimized to deposit pure and doped tetrahedral (ta-C) films and hydrogen and nitrogen incorporated ta-C films. The system has been modified and two novel techniques of “cathodic jet carbon arc (CJCA)” and “anodic jet carbon arc (AJCA)” have been implemented into the existing system. These modified arc based techniques have been used to deposit amorphous carbon films with embedded nanoparticles for enhanced tribological and field emission applications. Multilayer graphene is being made using FCVA system by depositing a-C films on metal substrates and post annealing the sample in vacuum at high temperatures.


Figure: Photograph of FCVA system

Microwave Plasma Enhanced Chemical Vapor Deposition (MWPECVD)

Very recently graphene has been recognized as a promising candidate for a variety of electronic devices such as transparent conducting electrodes and flexible flat panel displays. However, synthesis of large-scale graphene films with tunable thickness, compatible with established large-scale semiconductor technologies is very challenging. Various methods have been reported for the synthesis of graphene, such as mechanical exfoliation, chemical exfoliation, thermal decomposition of SiC, thermal chemical vapor deposition, However, a low temperature process for graphene synthesis would be indispensable for applications of graphene in electronic devices. Microwave plasma CVD (MWPECVD) has been shown to be successful in synthesizing diamond like carbon (DLC) films, carbon nanotubes (CNTs), nanowalls, nanosheets, diamond and nano diamond films. MWPECVD is thus envisioned as a potential method for the synthesis of defect free single and multi layered graphene films. A microwave plasma enhanced chemical vapor system (MWPECVD) has been designed and developed to deposit single and multilayered graphene. The system has vacuum capability of 3 x 10-7 Torr and operational pressure range up to 50 Torr. The substrates can be heated at a maximum temperature of 900 °C.


Figure: Photograph of MW-PECVD system

B. Characterization Systems:

             Field Emission Measurement Set Up


Figure: Photograph of Field Emission Measurement Set up

             Nano Indenter


Figure: Photograph of Nanoindenter

Recent Publications:

  • Effect of substrate bias in hydrogenated amorphous carbon films having embedded nanocrystallites deposited by cathodic jet carbon arc technique” by O. S. Panwar, Ishpal, R. K. Tripathi, A. K. Srivastava, Mahesh Kumar, Sushil Kumar, Diamond Relat. Mater. 25 (2012) 63-72.
  • Effect of Substrate Bias in Nitrogen Incorporated Amorphous Carbon Films with Embedded Nanoparticles Deposited by Filtered Cathodic Jet Carbon Arc Technique ” by O. S. Panwar, Sushil Kumar, Ishpal, A. K. Srivastava, Abhilasha Chouksey, R. K. Tripathi, A. Basu, Mater. Chem. Phys. 132(2-3)(2012)659-666.
  • Effect of Substrate bias in Amorphous Carbon Films Having Embedded Nanocrystallites ” by Ishpal, O. S. Panwar, A. K. Srivastava, Sushil Kumar, R. K. Tripathi, Mahesh Kumar, Sandeep Singh, Surf. Coat. Technol 206 (2011)155-164.
  • Role of Metallic Ni-Cr Dots on the Adhesion, Electrical, Optical and Mechanical Properties of Diamond- Like Carbon Thin Films” by Neeraj Dwivedi, Sushil Kumar , C.M.S. Rauthan, O. S. Panwar, Plasma Processes and Polymers 8(2) (2011) 100-107.
  • Effect of Ambient Gaseous Environment on the Properties of Amorphous Carbon Thin Films” by Ishpal, O. S. Panwar, Mahesh Kumar, Sushil Kumar, Mater. Chem. Phys.125 (2011) 558-567.
  • Effect of High substrate Bias and Hydrogen and Nitrogen Incorporation on the Spectroscopic Ellipsometric and Atomic Force Microscopic studies of Tetrahedral Amorphous Carbon films” by O. S. Panwar, Mohd Alim Khan, Satyendra Kumar, A. Basu, B. R. Mehta, Sushil Kumar, Ishpal, Surf. Coat. Technol. 205 (2010) 2126-2133.
  • X-ray photoelectron spectroscopy of Nitrogen Incorporated Amorphous Carbon Films Embedded with Nano particles Deposited Using Filtered Cathodic Jet Carbon Arc Technique” by Ishpal, O. S. Panwar, Mahesh Kumar , Sushil Kumar, Appl. Surf. Sci. 256 (2010) 7371-7376.
  • Effect of High substrate Bias and Hydrogen and Nitrogen Incorporation on Density of States and Emission threshold in Tetrahedral Amorphous Carbon films” by O. S. Panwar, Mohd Alim Khan, R. Bhattacharyya, B. R. Mehta, Sushil Kumar and Ishpal, B.S. Satyanarayana, J. Vac. Sci. Technol. B 28 (2010) 411-422.
  • Field emission from as grown and nitrogen incorporated tetrahedral amorphous carbon / silicon heterojunctions grown using a pulsed filtered cathodic vacuum arc technique” by O. S. Panwar, Nalin Rupesinghe and G.A.J. Amaratunga, J. Vac. Sci. Technol. B 26 (2008) 566-575.
  • Effect of high substrate bias and hydrogen and nitrogen incorporation on filtered cathodic vacuum arc deposited tetrahedral amorphous carbon films” by O. S. Panwar, Mohd. Alim Khan, Mahesh Kumar, S.M. Shivaprasad, B.S. Satyanarayana, P.N. Dixit, R. Bhattacharyya and M. Y. Khan, Thin Solid Films 516 (2008)2331-2340.

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