8-12 July 2013
Africa/Johannesburg timezone
<a href="http://events.saip.org.za/internalPage.py?pageId=13&confId=32"><font color=#ff0000>SAIP2013 PROCEEDINGS AVAILABLE</font></a>

The Electrical Transport Properties of Bulk Nitrogen Doped Carbon Microspheres

10 Jul 2013, 14:10
20m
Oral Presentation Track A - Division for Condensed Matter Physics and Materials DCMPM1

Speaker

Mr William Wright (University of the Witwatersrand)

Apply to be<br> considered for a student <br> &nbsp; award (Yes / No)?

Yes

Abstract content <br> &nbsp; (Max 300 words)

The electrical transport properties of Nitrogen doped Carbon microspheres are experimentally investigated using a number of well-established techniques. Four samples of bulk nitrogen doped carbon microspheres were synthesised using a horizontal chemical vapour deposition reaction. The samples, with varying levels of Nitrogen dopant, are then characterised using EPR (electron paramagnetic resonance) and Raman spectroscopy to confirm the amorphous carbon structure and dopant level so that accurate comparisons between the properties of samples can be made. Raman data gives characteristic spectra of disordered carbon and the Ratios of the ID and IG peaks are calculated. EPR measurements allowed for comparisons between the number of paramagnetic centres in each sample to be compared. This offers a non-destructive technique to determine relative dopant levels and, if a standard is known, absolute dopant levels. Results of temperature dependent four probe resistance measurements on the four samples are presented. Attempts to explain these results using a fluctuation assisted tunnelling model and variable range hopping are explored. The apparent occurrence of a metal insulator transition in some samples is shown and attempts to explain this effect by dopant desorption is presented. The results of a series of variable temperature, high and low bias regime IV Characteristics experiments are presented. Attempts to explain the results of these experiments using a fluctuation assisted tunnelling and thermal activation model explored. The initial results of a series of field dependent and angle dependent magneto resistance experiments are presented and ideas for further experiments to shed light on the transport properties of the samples are given.

Main supervisor (name and email)<br>and his / her institution

Dr J. M. Keartland, keartland@psi.phys.wits.ac.za, University of the Witwatersrand

Would you like to <br> submit a short paper <br> for the Conference <br> Proceedings (Yes / No)?

Yes

Level for award<br>&nbsp;(Hons, MSc, <br> &nbsp; PhD)?

MSc

Primary author

Mr William Wright (University of the Witwatersrand)

Co-authors

Dr Jonathan Keartland (University of the Witwatersrand) Mr Vincent Marsicano (University of the Witwatersrand)

Presentation Materials

Peer reviewing

Paper