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
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Diamond properties
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
3
PTFE (Teflon)
 > 1018 -cm
(room temperature)
Superconductors  ~ 0
Silicon
 ~ 104 -cm
(room
temperature)
Pure metal
 ~ 10-10 -cm
(1 K)
Tin  ~ 10-5 -cm
(room temperature)
Diamond  ~ 1016 -cm
(room temperature)
10-10
1
1010
1020
Resistivity (ohm-cm)
4
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Bad way to measure Resistivity, 
Ohm’s law
V=IR
R = L/A
sample
Length, L
Area, A
5
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Bad way to measure Resistivity, 
Source voltage, V
Measure current, I
A
Ohm’s law
V=IR
R = L/A
sample
Length, L
Area, A
6
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Measuring contact resistance
Source voltage, V
Measure current, I
A
Ohm’s law
V=IR
Study one contact
at a time
sample
Length, L
Area, A
7
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Measuring contact resistance
I–V characteristics for
Ohm’s
law
V=IR
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)
8
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Measuring contact resistance
I–V characteristics for
Ohm’s
law
V=IR
rectifying
and1020
Ohmic
Above
K,contacts
for aluminium on p-diamond
bulk carbide
(001). The left panel shows a
(Al3C
4) formation
rectifying
Al–diamond
contact
occurs
(curve
A) andcreating
a carbide–
Ohmic
contacts
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)
9
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
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
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
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
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Rectifying
Current
Time
12
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Four Point Probe Resistivity, 
Source current, I
Measure voltage, V
Ohm’s law
V=IR
V
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
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Bad way to measure Resistivity, 
Source Voltage, V
Measure current, I
Ohm’s law
V=IR
A
R = L/A
sample
Length, L
Area, A
14
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Four Point Probe Resistivity, 
Source current, I
Measure voltage, V
Ohm’s law
V=IR
V
R = L/A
sample
Length, L
Area, A
15
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Lock-in amplifiers
AC source current, I
reference
V
signal
Lock-in
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
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Hall Effect
Source current, I
Lorentz Force:
F = q (E+ v × B)
sample
V
Applied
magnetic field, B
Chapter, 8 and 10 and Appendix F, Singleton,
and page 164, Kittel
Hall Effect
Sample
thickness,
d
17
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Chapter, 8 and 10 and Appendix F, Singleton,
and page 164, Kittel
18
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
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
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Wire bonding
Image by Holger
Motzkau
http://en.wikipedia.org/wiki/File
:Ultrasonic_wedge_bonding.w
ebm
20
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
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 Review
20: 220–224 (1958)
Experimental considerations in measuring
resistivity, Page 197, Singleton, Band Theory and
Electronic Properties of Solids, OUP 2001
21
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
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
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
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
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Diamond Superconductivity
k=0
For Cooper
pair
Page 202, Singleton, Band Theory and Electronic
Properties of Solids, OUP 2001
24
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Diamond Superconductivity
E A Ekimov et al,
Superconductivity
in diamond,
Nature 428, 542
(2004)
25
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
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)
26
Module 2 – Properties and Characterization of Materials
- Lecture 9 – Electrical Characterization
Lecture
9
Electrical characterization
- Schottky and Ohmic contacts
- 4 point probe measurements
- Lock-in measurements
- Hall effect
- Sample geometries
- Temperature dependence
- Superconductivity
10
Electron microscopy:
- Scanning electron microscopy
- Transmission electron microscopy