Dr David Carey

Biography

• Senior Lecturer (2009) in Electronic Engineering
• Lecturer (2004) in Electronic Engineering
• EPSRC Advanced Research Fellowship (2002 - 2007)
• PhD degree from the University of Dublin, Trinity College.  

Research Interests

Current research interests include (with links to publications)

• Band gap engineering and characterisation of graphene and bilayer graphene: We are studying the doping of graphene and bilayer graphene in order to control the carrier concentration and induce an electronic and optical band gap. We also aim to understand charge transfer in the graphene - molecule system which is important for graphene molecular sensors. 
  • Ab initio density functional theory (DFT) calculations of molecular doping of bilayer graphene (BLG). NEW: See our latest publication (March 2013) in ACS Nano on band gap engineering and opening up an electrical band gap of up to 150 meV in BLG using molecular dopants. We also show selective optical absorption in the 3-5 μm region of the spectrum and could be important for graphene photodetectors. 
  • Electrical and Raman characterisation of low substrate temperature (415^oC) photothermal chemical vapour deposition of graphene on Cu. Using an optical source it is possible to efficiently couple energy into the metal catalyst growth surface while the substrate is held at over 250^oC lower in temperature. 
  • We are also looking at phonon effects and band structure in 2D layered materials including graphene and silicene.

• Metallic nanoparticles for high frequency electronics and antennas: We are interested in high frequency electrical conduction and have explored the high frequency characterization, up to 220 GHz, of low temperature processed metal nanoparticles. We have shown, published in ACS Applied Materials in December 2012, that the high frequency electrical losses of screen printed mm-long coplanar waveguide structures of metallic nanoparticles are lower than that of conventional thick-film paste micron-sized silver grains. The improved response is due to the better packing and the smoother surface. AFM measurements show that silver nanoparticles have about 1/3 the rms roughness compared to the micron-sized silver grains. The use of metallic nanoparticles in this way may offer a route to efficient, flexible conformal antennas. 

• Carbon nanotube-polymer composites for large area electronic applications: 
  • See our press release on high frequency (up to 220 GHz) applications of carbon nanotube polymer composites, which was published in Applied Physics Letters in October 2011, and showed low electrical losses (0.15 dB/mm) are possible in electrical conductors made from CNT-PMMA composites up to 25 mm in length. 
  • Our study of field emission from CNT-polymer composites, published in Small in 2009, has attracted considerable attention as it shows the importance of chemical functionalisation for efficient nanotube dispersion to minimize material wastage while retaining excellent electrical characteristics. Its impact is seen in several of areas of carbon nanotube engineering, including composite manufacture, large area transparent conductors and displays.
  • Both topics rely on how knowledge of functional materials processing can be used to tailor specific, in this case electrical, properties for large area applications. 

• Current diamond-like carbon and carbon based electronics:  We continue to work on examining the electronic and transport properties of DLC with collaborators at the Indian Institute of Technology, Delhi and the National Physical Laboratory, Delhi looking at 
  • NEW metal induced sp³--> sp² bonding transformation in DLC films and the reduction of threshold field for electron emission (accepted for publication in ACS Applied Materials and Interfaces April 2013). 
  • how inducing a nanostructured surface for DLC films can reduce the threshold field for emission (published ACS Applied Materials and Interfaces in 2012) and 
  • measurement of the electrical, spectroscopic and photoconductive properties of in DLC films (published in the Journal of Applied Physics in 2012).       

• Previous studies of diamond-like carbon and carbon based electronics: Previous studies have explored the role of the sp² phase embedded in sp³ matrix has had on the threshold field for electron emission; how current conditioning of DLC films can improve their electrical performance and reduce device hysteresis (which have implications for memristor materials) and electron delocalisation and transport in disordered sp² films. I was also the Guest Editor of the Journal of Material Science: Materials in Electronics for a Special Issue on Carbon Based Electronics published in the Journal of Material Science: Materials in Electronics.

• The structure, electrical transport and electronic properties of nanomaterials (with links to some papers) including
  • a new way to accurately calculate the electric field potential around a high aspect emitter 
  • explain the appearance of steps and plateaus in the I-V characteristics from quantum tunnelling from a nanoparticle 
  • ab initio density functional theory calculations on hydrogen storage on and inside carbon nanotubes
  • growth and electron emission from ZnO nanorods (in collaboration with DCU)
  • structural characterization of MoSI nanowires (in collaboration with Trinity College Dublin)
  • how electrode geometry plays an important role in defining the field enhancement factor in field emitters
  • development of an in-situ three terminal focussed ion beam gate electrode where single nanotube field emitters can be studied in an electron microscope and estimates of the gate transparency can be made.

• Rare Earth ion magnetic resonance (EPR) and Si optoelectronics: Previous projects included the first study of the EPR defects of Er³⁺ centres in oxygen co-implanted Si and the identification of the C_1h monoclinic symmetry defect centre.  We explored how the Er³⁺:O ratio and Er³⁺:F ratio affected the ESR and photoluminescence properties in Si. A variety of ESR active centres with monoclinic C_1h point group symmetry and trigonal symmetry were found.  This work was followed up by an examination of the validity of the cubic crystal field approximation for trigonal and tetragonal symmetry erbium 3+ centres.

• Commercial applications of nanomaterials and societal impact Nanomaterials in general and carbon nanotubes and graphene, nanomaterials for high frequency applications in particular. Nanotechnology and public perception and society. See, for example, presentation and round table discussion on Developments in Nanotechnology and Contemporary International Intervention in July 2012.

PhD positions are available to highly qualified candidates in all of the above areas, especially in graphene and high frequency characterisation of nanomaterials.

Publications

Here is a list of selected research papers with links

1. Molecular Doping and Band Gap Opening of Bilayer Graphene, Alexander J. Samuels and J. David Carey, ACS Nano 7, 2790 (2013).
2. Influence of Silver Incorporation on the Structural and Electrical Properties of Diamond-Like Carbon Thin Films, Neeraj Dwivedi, Sushil Kumar, J. David Carey, R. K. Tripathi, Hitendra K. Malik and  M. K. Dalai, Accepted for publication in Applied Materials and Interfaces, volume 5, April 2013.
3. Enhanced Electrical Conductivity of Silver Nanoparticles for High Frequency Electronic Applications, Ali H. Alshehri, Malgorzata Jakubowska, Anna Młożniak, Michal Horaczek, Diana Rudka, Charles Free and J. David Carey, ACS Appl. Mater. Interfaces 4, 7007 (2012). Local copy available here.
4. Photoconductivity and Characterization of Nitrogen Incorporated Hydrogenated Amorphous Carbon Thin Films, Neeraj Dwivedi, Sushil Kumara, J. D. Carey, Hitendra K. Malik and Govind, J. Appl. Phys.112, 113706 (2012). Local copy available here.
5. Structural and Electronic Characterization of Nanocrystalline Diamond-Like Carbon Thin Films, Neeraj Dwivedi, Sushil Kumara, R. K. Tripathi, J David Carey, Hitendra K. Malik and M. K. Dalai, ACS Appl. Mater. Interfaces 4, 5309 (2012). Local version available here.
6. Photo-thermal chemical vapor deposition growth of graphene, Y.Y. Tan, K.D.G.I. Jayawardena, A.A.D.T. Adikaari, L.W. Tan, J.V. Anguita, S.J. Henley, V. Stolojan, J.David Carey, S.R.P. Silva, Carbon 50, 668 (2012). Local version available here.
7. Electrical Performance of Carbon Nanotube – Polymer Composites at Frequencies up to 220 GHz, Ali H. Alshehri, Malgorzata Jakubowska, Marcin Sloma, Michal Horaczek, Diana Rudka, Charles Free and J. David Carey, Appl. Phys. Lett. 99, 153109 (2011). Local version available here.
8. Exact equipotential profile mapping: A self-validating method, L.D Filip, J D Carey and S.R.P. Silva, J. Appl. Phys. 109, 084527 (2011). Local version available here.
9. Field effect in chemical vapour deposited graphene incorporating a polymeric gate dielectric, Y. Y. Tan, L. W. Tan, K. D. G. I Jayawardena, J.V. Anguita, J. D. Carey and S. R. P. Silva, Synthetic Metals 161, 2249 (2011).
10. Effect of transparent electrode on the performance of bulk heterojunction solar cells, A. A. Damitha T. Adikaari, Joe Briscoe, Steve Dunn, J. David Carey and S. Ravi P. Silva, Mater. Res. Soc. Symp. 1270, HH14-23 (2010).
11. Carbon Nanotube – Polymer Nanocomposites for Field Emission Cathodes, Thomas Connolly, Richard C. Smith, Yenny Hernandez, Yurii Gun’ko, Jonathan N. Coleman and J. David Carey, Small 5, 826 (2009). Local version available here.
12. Two-step electron tunnelling from confined electronic states in a nanoparticle, L.D. Filip, M. Palumbo, J. David Carey, S.R.P. Silva, Phys. Rev B 79, 245429 (2009).
13. State mixing and the cubic crystal field approximation for rare earth ions: the case of the Er³⁺ ion in axial crystal fields,  J David Carey, J. Phys. Condensed Matter 21, 175601 (2009). Local version available here.
14. On the importance of the electrostatic environment on the transport properties of freestanding multiwall carbon nanotubes, Paul Smith, J David Carey, David C Cox, Roy D Forrest and S. R. P. Silva,  Nanotechnology 20, 145202 (2009).  Highlighted in Nanotechweb.org website. 
15. Molecular physisorption on graphene and carbon nanotubes: a comparative ab initio study, Daniel Henwood and David Carey. Invited article for a Special issue of Molecular Simulation 34, 1019 (2008).  Local version available here.
16. Ab initio investigation of molecular hydrogen physisorption on graphene and carbon nanotubes, Daniel Henwood and J David Carey, Phys. Rev. B 75, 245413 (2007).  Local version available here.
17. Observation of van der Waals driven self-assembly of MoSI nanowires into a low-symmetry structure using aberration-corrected electron microscopy, V. Nicolosi, P. D. Nellist, S. Sanvito, E. C. Cosgriff, S. Krishnamurthy, W. J. Blau, M. L. H. Green, D. Vengust, D. Dvorsek, D. Mihailovic, G. Compagnini, J. Sloan, V. Stolojan, J. D. Carey, S. J. Pennycook, J. N. Coleman, Advanced Materials 19, 543 (2007).
18. Quantifying clustering in disordered carbon thin films, J. David Carey, Thin Solid Films 515, 996 (2006).
19. Silver nanoparticle decorated carbon nano-scaffolds: Application as a sensing platform, S.J. Henley, J.D. Carey and S.R.P. Silva, Appl. Phys. Lett. 89, 183120 (2006).  Local version available here.
20. In-situ electrode manipulation for three terminal field emission characterisation of individual carbon nanotubes, R.C. Smith, J.D. Carey, D.C. Cox and S.R.P. Silva, Appl. Phys. Lett. 89, 063111 (2006). Local version available here.
21. Charge transport effects in field emission from carbon-nanotube polymer composites, R C Smith, J D Carey, R J Murphy, W J Blau, J N Coleman and S R P Silva, Appl. Phys. Lett. 87, 263105 (2005).  Local version available here.
22. Pulsed-laser-induced nanoscale island formation in thin metal-on-oxide films, S J Henley, J D Carey and S R P Silva, Phys. Rev. B 72, 195408 (2005).  Local version available here.
23. Dynamics of confined plumes during short and ultrashort pulsed laser ablation of graphite, S J Henley, J D Carey, S R P Silva, G M Fuge, M N R Ashfold and D Anglos, Phys. Rev. B 72, 205413 (2005).  Local version available here.
24. Interpretation of enhancement factor in nonplanar field emitters, R C Smith, R D Forrest, J D Carey, W K Hsu and S R P Silva, Appl. Phys. Lett. 87, 013111 (2005). Local version available here.
25. Disorder, clustering, and localization effects in amorphous carbon, J D Carey and S R P Silva, Phys. Rev. B 70, 235417 (2004).  Local version available here.
26. Origin of electric field enhancement in field emission from amorphous carbon thin films, J. David Carey, R. D. Forrest and S. R. P. Silva, Appl. Phys. Lett. 78, 2339 (2001). Local version available here.
27. Conditioning of hydrogenated amorphous carbon thin films for field emission via current stressing, J. David Carey and S.R.P. Silva, Appl. Phys. Lett. 78, 347 (2001).  Local version available here. 
28. Influence of sp² clusters on the field emission properties of amorphous carbon thin films, J. David Carey, R. D. Forrest, R.U.A. Khan, and S.R.P. Silva, Appl. Phys. Lett. 77, 2006 (2000).  Local version available here.
29. Electron paramagnetic resonance and photoluminescence study of Er-Impurity Complexes in Si, J. D. Carey, R. C. Barklie, J. F. Donegan, F. Priolo, G. Franzò, and S. Coffa, Phys. Rev. B 59, 2773 (1999).      
30. Electron paramagnetic resonance of erbium doped silicon, J. D. Carey, J. F. Donegan,  R. C. Barklie, F. Priolo, G. Franzò, and S. Coffa, Appl. Phys. Lett. 69, 3854 (1996).

Book Chapters and Review Articles

1. Effects of nanoscale clustering in amorphous carbon, David Carey and Ravi Silva, Carbon: The Future Material for Advanced Technology Applications, Springer Series Topics in Applied Physics, volume 100, pp 131-145 (March 2006).
2. Nanostructured materials for field emission devices, J.D. Carey and S.R.P. Silva, CRC Handbook on Nanomaterials, Ed. Y. Gogotsi, (January 2006)

Teaching

Current or recent lecture courses
1. Nanoelectronics and Devices (EEEM022) to MSc students (FHEQ 7).

2. Introduction to Nanotechnology (EEE3025) to year 3 undergraduate students (FHEQ 6).

3. Digital Engineering and Integrated Circuits (EEE2034) to year 2 undergraduate students (FHEQ 5)

Past modules include

1.  Electronic Devices and Integrated Circuits (Year 2/FHEQ 5).

2.  Introduction to Computer Logic (Year 1/FHEQ 4).

A list of final year and MSc projects is available. Please contact me by email if you are interested.

Departmental Duties

• Deputy Director of Undergraduate Studies, Department of Electronic Engineering
• Programme Director, MSc in Nanotechnology and Nanoelectronic Devices
• MSc Admissions tutor
• Member of the Degree Validation Boards and MSc External Examiner

PhD Research Positions

Other information