1 / 26

Gavin W Morley Department of Physics University of Warwick

This lecture discusses the properties and characterization of materials, focusing on electronic characterization of diamond and Teflon. Topics covered include resistivity measurements, contact resistance, Schottky barriers, four-point probe resistivity, lock-in amplifiers, Hall effect, van der Pauw method, temperature dependence, and diamond superconductivity.

rfelipe
Télécharger la présentation

Gavin W Morley Department of Physics University of Warwick

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Gavin W Morley Department of Physics University of Warwick Diamond Science & Technology Centre for Doctoral Training, MSc course Module 2 – Properties and Characterization of Materials (PX904) Lecture 9 – Electronic characterization

  2. Diamond properties

  3. PTFE (Teflon)  > 1018 -cm (room temperature) Silicon  ~ 104 -cm (room temperature) Pure metal  ~ 10-10 -cm (1 K) Tin  ~ 10-5 -cm (room temperature) Superconductors  ~ 0 Diamond  ~ 1016 -cm (room temperature) 10-10 1 1010 1020 Resistivity (ohm-cm)

  4. Bad way to measure Resistivity,  Ohm’s law V = I R R = L/A sample Length, L Area, A

  5. Bad way to measure Resistivity,  Source voltage, V Measure current, I A Ohm’s law V = I R R = L/A sample Length, L Area, A

  6. Measuring contact resistance Source voltage, V Measure current, I A Ohm’s law V = I R Study one contact at a time sample Length, L Area, A

  7. Measuring contact resistance I–Vcharacteristics for rectifying and Ohmic contacts for aluminium on p-diamond (001). The figure shows a rectifying Al–diamond contact (curve A) and a carbide–diamond Ohmic contact (curve B) prepared by in vacuo annealing of an Al contact. D A Evans et al., Diamond–metal contacts: interface barriers and real-time characterization, J. Phys.: Condens. Matter 21, 364223 (2009) Ohm’s law V = I R

  8. Measuring contact resistance I–Vcharacteristics for rectifying and Ohmic contacts for aluminium on p-diamond (001). The left panel shows a rectifying Al–diamond contact (curve A) and a carbide–diamond Ohmic contact (curve B) prepared by in vacuo annealing of an Al contact. D A Evans et al., Diamond–metal contacts: interface barriers and real-time characterization, J. Phys.: Condens. Matter 21, 364223 (2009) Ohm’s law V = I R Above 1020 K, bulk carbide (Al3C4) formation occurs creating Ohmic contacts

  9. Schottky contacts Depletion layer Wolfgang Pauli: ‘‘God made the bulk; the surface was invented by the devil’’ Schottky barrier for n-type semiconductor, Page 573, Kittel, Introduction to Solid State Physics, Wiley 1996

  10. Schottky contacts Schottky barrier height is  Raymond T Tung, The physics and chemistry of the Schottky barrier height, Applied Physics Reviews 1, 011304 (2014)

  11. Rectifying Current Time

  12. Four Point Probe Resistivity,  Source current, I V Measure voltage, V Ohm’s law V = I R R = L/A sample Length, L Area, A Experimental considerations in measuring resistivity, Pages 194-199, Singleton, Band Theory and Electronic Properties of Solids, OUP 2001

  13. Bad way to measure Resistivity,  Source Voltage, V A Measure current, I Ohm’s law V = I R R = L/A sample Length, L Area, A

  14. Four Point Probe Resistivity,  Source current, I V Measure voltage, V Ohm’s law V = I R R = L/A sample Length, L Area, A

  15. Lock-in amplifiers AC source current, I reference V Lock-in signal sample Component of signal at reference frequency Experimental considerations in measuring resistivity, Pages 194-199, Singleton, Band Theory and Electronic Properties of Solids, OUP 2001

  16. Hall Effect Source current, I Lorentz Force: F = q (E+ v × B) V sample Applied magnetic field, B Chapter, 8 and 10 and Appendix F, Singleton, and page 164, Kittel

  17. Hall Effect Sample thickness, d Chapter, 8 and 10 and Appendix F, Singleton, and page 164, Kittel

  18. Hall Effect Source current, I Make Hall bar from thin film samples with lithography Experimental considerations in measuring resistivity, Pages 194-199, Singleton, Band Theory and Electronic Properties of Solids, OUP 2001

  19. Wire bonding Image by Holger Motzkau http://en.wikipedia.org/wiki/File:Ultrasonic_wedge_bonding.webm

  20. van der Pauw Sample geometries The van der Pauw method L J van der Pauw, A method of measuring the resistivity and Hall coefficient on lamellae of arbitrary shape. Philips Technical Review20: 220–224 (1958) Experimental considerations in measuring resistivity, Page 197, Singleton, Band Theory and Electronic Properties of Solids, OUP 2001

  21. Temperature dependence M Werner et al., Charge transport in heavily B-doped polycrystalline diamond films, Applied Physics Letters 64, 595 (1994) Sample A is metallic

  22. Diamond surfaces Wolfgang Pauli: ‘‘God made the bulk; the surface was invented by the devil’’ O A Williams and RB Jackman, Surface conductivity on hydrogen terminated diamond, Semicond. Sci. Technol. 18 (2003) S34

  23. Diamond Superconductivity k = 0 For Cooper pair Page 202, Singleton, Band Theory and Electronic Properties of Solids, OUP 2001

  24. Diamond Superconductivity E A Ekimov et al, Superconductivity in diamond, Nature 428, 542 (2004)

  25. Diamond Superconductivity E Bustarret et al, Dependence of the Superconducting Transition Temperature on the Doping Level in Single-Crystalline Diamond Films, Physical Review Letters, 93, 237005 (2004)

More Related