IEC 62830-2:2017

Semiconductor devices - Semiconductor devices for energy harvesting and generation - Part 2: Thermo power based thermoelectric energy harvesting

IEC 62830-2:2017 describes procedures and definitions for measuring the thermo power of thin films used in micro-scale thermoelectric energy generators, micro heaters and micro coolers. This part of IEC 62830 specifies the methods of tests and the characteristic parameters of the thermoelectric properties of wire, bulk and thin films which have a thickness of less than 5 mm and energy harvesting devices that have thermoelectric thin films, in order to accurately evaluate their performance and practical uses. This part of IEC 62830 is applicable to energy harvesting devices for consumer, general industries, military and aerospace applications without any limitations of device technology and size.

Dispositifs à semiconducteurs - Dispositifs à semiconducteurs pour récupération et production d'énergie - Partie 2: Récupération d'énergie thermoélectrique basée sur la puissance thermoélectrique

L'IEC 62830-2:2017 décrit des procédures et donne des définitions sur la mesure de la puissance thermoélectrique de couches minces utilisées dans des générateurs d'énergie thermoélectrique à très petite échelle, des microréchauffeurs ou des microrefroidisseurs. La présente partie de l'IEC 62830 spécifie les méthodes d'essais et les paramètres des caractéristiques des propriétés thermoélectriques des fils, des couches volumiques et des couches minces d'épaisseur inférieure à 5 mm ainsi que des dispositifs de récupération d'énergie dotés de couches minces thermoélectriques, afin d'évaluer avec précision leurs performances et leur utilisation pratique. La présente partie de l'IEC 62830 s'applique aux dispositifs de récupération d'énergie destinés à des applications grand public, industrielles, militaires et aérospatiales sans limitation sur la taille ni sur la technologie des dispositifs.

General Information

• Status: Published
• Publication Date: 19-Jan-2017
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 31.080.99 - Other semiconductor devices
• Technical Committee: TC 47 - Semiconductor devices
• Drafting Committee: WG 7 - TC 47/WG 7
• Current Stage: PPUB - Publication issued
• Start Date: 20-Jan-2017
• Completion Date: 04-Feb-2017

Standards Content (Sample)

IEC 62830-2 ®
Edition 1.0 2017-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Semiconductor devices – Semiconductor devices for energy harvesting and
generation –
Part 2: Thermo power based thermoelectric energy harvesting

Dispositifs à semiconducteurs – Dispositifs à semiconducteurs pour
recupération et production d'énergie –
Partie 2: Récupération d'énergie thermoélectrique basée sur la puissance
thermoélectrique
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IEC 62830-2 ®
Edition 1.0 2017-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Semiconductor devices – Semiconductor devices for energy harvesting and

generation –
Part 2: Thermo power based thermoelectric energy harvesting

Dispositifs à semiconducteurs – Dispositifs à semiconducteurs pour

recupération et production d'énergie –

Partie 2: Récupération d'énergie thermoélectrique basée sur la puissance

thermoélectrique
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.080.99 ISBN 978-2-8322-3830-1

– 2 – IEC 62830-2:2017 © IEC 2017
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Testing methods . 6
4.1 General . 6
4.2 Thermo-power measurement . 6
4.2.1 Integral method . 6
4.2.2 Differential method . 8
4.3 Thermal conductivity measurement . 11
4.3.1 General . 11
4.3.2 Transient 3ω method . 12
4.3.3 Test report . 13
Annex A (informative) Thermoelectric energy generator . 14
Bibliography . 15

Figure 1 – Schematic diagram of integral method for measurement of the thermo-
power of thermoelectric materials . 7
Figure 2 – Schematic diagram of the differential method for measuring the thermo-
power . 9
Figure 3 – Diagram of the setup for measuring electrical resistivity and Seebeck
coefficient using differential method . 10
Figure 4 – Schematic diagram of measuring in-plane thermal conductivity of thin film
on the substrate . 12
Figure 5 – The MEMS structure for measuring thermal conductivity of thin film
materials using transient 3ω method. . 12

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SEMICONDUCTOR DEVICES – SEMICONDUCTOR DEVICES
FOR ENERGY HARVESTING AND GENERATION –

Part 2: Thermo power based thermoelectric energy harvesting

FOREWORD
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International Standard IEC 62830-2 has been prepared by IEC technical committee 47:
Semiconductor devices.
The text of this standard is based on the following documents:
FDIS Report on voting
47/2329/FDIS 47/2352/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – IEC 62830-2:2017 © IEC 2017
A list of all the parts in the IEC 62830 series, published under the general title Semiconductor
devices – Semiconductor devices for energy harvesting and generation, can be found on the
IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
SEMICONDUCTOR DEVICES – SEMICONDUCTOR DEVICES
FOR ENERGY HARVESTING AND GENERATION –

Part 2: Thermo power based thermoelectric energy harvesting

1 Scope
This part of IEC 62830 describes procedures and definitions for measuring the thermo power
of thin films used in micro-scale thermoelectric energy generators, micro heaters and micro
coolers. This part of IEC 62830 specifies the methods of tests and the characteristic
parameters of the thermoelectric properties of wire, bulk and thin films which have a thickness
of less than 5 µm and energy harvesting devices that have thermoelectric thin films, in order
to accurately evaluate their performance and practical uses. This part of IEC 62830 is
applicable to energy harvesting devices for consumer, general industries, military and
aerospace applications without any limitations of device technology and size.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
Seebeck coefficient
S
magnitude of an induced thermoelectric voltage in response to a temperature difference
across a material, and the entropy per charge carrier in the material
3.2
thermal conductivity
k
at a point fixed in a medium with a temperature field, scalar quantity λ characterizing the
ability of the medium to transmit heat through a surface element containing that point: φ=-k
grad T, where φ is the density of heat flow rate and T is thermodynamic temperature
Note 1 to entry: In an anisotropic medium, thermal conductivity is a tensor quantity.
Note 2 to entry: The coherent SI unit of thermal conductivity is watt per metre kelvin, W/(m·K).
[SOURCE: IEC 60050-113:2011, 113-04-38]
3.3
electrical conductivity
specific conductance
σ
value of a material’s ability to conduct an electrical current

– 6 – IEC 62830-2:2017 © IEC 2017
3.4

figure of merit
Z
characteristic value of thermoelectric films given by the convolution of electrical conductivity
and the square of the Seebeck coefficient divided by thermal conductivity
4 Testing methods
4.1 General
It is indispensable to measure the thermo-power to establish the thermoelectric devices. The
electrical resistivity and the thermopower shall be measured in order to define the
thermoelectric properties of the materials used for fabrication of thermoelectric devices.
Generally to measure these values the materials should be investigated under temperature
from between 3 K and 300 K. There are two types of measuring methods for thermo-power
measurement. The first is the integral method and the other is the differential method. In case
of measuring the electrical conductance the electrical resistivity is to be measured and the
reciprocal number of the measured value is to be used.A four-point proof method is typically
used in electrical resistivity. When this method is used, the total voltage drop can be
measured by the sum of resistive voltage and Seebeck voltage. To obtain resistive voltage
without the Seebeck-induced voltage, very fast switching DC or AC measurement is needed to
measure the electrical resistivity. In addition, the sample will be prepared of a wire type which
has a diameter under 200 µm and thin films which have been deposited onto the silicon
substrate with a 100 nanometer insulating layer.
4.2 Thermo-power measurement
4.2.1 Integral method
4.2.1.1 General
The integral method is a very simple method of obtaining the thermo-power value for
thermoelectric materials. The generated voltage change between the reference material and
sample material is used for the calculation of the thermo-power value of the materials. In this
method the materials shall be fabricated in wire form to make a thermocouple form. The third
thermocouple can be attached to the hot junction of the reference and sample wire to
measure the temperature of the junction.
The schematic diagram of the integral method to measure the thermo-power of thermoelectric
materials is shown in Figure 1.

T
a
V V
x t
T
Sample wire Reference wire
T
IEC
Key
T: temperature to be measured T : temperature of ambient
a
T : temperature of cold junction
V , V : voltmeter which can measure the voltage drop
x t
Figure 1 – Schematic diagram of integral method for measurement
of the thermo-power of thermoelectric materials
At the thermocouple of the measured material and the reference the potential difference can
be measured using equations (1) and (2).
term2 term2
(1)
ΔV=− Edl=− α∇Tdl
∫ ∫
term1 term1
Or
T T T T T
0 0 a a
 
ΔV=− α dT+ α dT+ α dT+ α dT =− (α −α )dT
 
Cu x ref Cu x ref (2)
∫ ∫ ∫ ∫ ∫
T T T T T
a 0 0 0
 
where T is temperature of cold junction of the thermocouples and T is usually absolute value
0 a
of T = 274,15 K. As shown in the equation (3), the numerical differentiation of the measured
voltage change of the thermocouple has been derived.

– 8 – IEC 62830-2:2017 © IEC 2017
d∆V
=−(α −α )
(3)
x ref
T
dT
Finally the value of the sample wire’s thermo-power is obtained using equation (4) when the
thermo-power of the reference material has been already known.
d∆V
α (T)=−  +α (T)
x ref
 
(4)
dT
 
T
4.2.1.2 Test procedure
a) Form a wire of sample material using any kind of method to make a wire form.
b) Join the sample material wire and reference wire for using hot junction.
c) Attach another third wire for measuring the temperature of hot junction.
d) Place one voltmeter between the third wire and reference wire.
e) Place the other voltmeter between the reference wire and the sample wire
f) Read the voltage difference between the sample and reference wire.
g) Calculate the thermo-power using equation (4).
4.2.2 Differential method
4.2.2.1 General
The differential method is measuring two points of material to be measured. The potential
difference can be also measured simultaneously when the net current through the sample is
zero. At that time the electrical field in the measuring sample is given by E = α∆T which is due
to thermo-power. In Figure 2 the schematic diagram of the differential method for measuring
thermo-power is shown.
T
a
1 2
V
x
V
V
t2
t1
T
Heater
Heat sink
T T
2 1
IEC
Key
T , T : temperature to be measured T : temperature of ambient
1 2 a
T : temperature of cold junction
V , V , V : voltmeter which can measure the voltage drop
x t1 t2
Figure 2 – Schematic diagram of the differential method
for measuring the thermo-power
When the thermocouple wires and the sample are joined homogeneously, measuring errors
can be minimized and equations (5), (6) and (7) can be used for calculation of the thermo-
power of the materials. Under these conditions potential difference is given by the equation.
T T T T T
0 1 2 0 a
 1 2 
ΔV=− α dT+ α dT+ α dT+ α dT+ α dT
 
Cu ref x ref Cu (5)
∫ ∫ ∫ ∫ ∫
T T T T T
a 0 1 2 0
 
For a homogeneous reference wire the second and the fourth integral terms can be merged
and the equation (5) can be modified into a more simple equation (6).
T
ΔV=− (α −α )dT
(6)
x ref
∫
T
If the temperature difference is only given by the difference between point 1 and point 2, the
final simplified form is given as shown in equation (7).
ΔV
α(T )=− +α (T )
(7)
x av ref av
ΔT
– 10 – IEC 62830-2:2017 © IEC 2017
when the T is given by the half of the sum of the T and T .
av 1 2
4.2.2.2 Test Procedure
The diagram of the setup for the measurement of the resistivity and Seebeck coefficient of
bulk materials using the differential method is shown in Figure 3.
I
heater
Heater
Copper block
+
I
+
V
TEP
+
V
R
∆T
Sample
–
V
R
–
I
–
V
TEP
Copper block
IEC
Key
∆T: temperature difference I : current for heater
heater
+ -
I : positive current I : negative current
V : resistive positive voltage V : resistive negative voltage
R+ R-
V : thermoelectric positive voltage V : thermoelectric negative voltage
TEP+ TEP-
Figure 3 – Diagram of the setup for measuring electrical resistivity
and Seebeck coefficient using differential method
In thermoelectric materials the Seebeck coefficient is relatively larger than non-thermoelectric
materials. So the total voltage across the sample shall be the summation of the Seebeck
voltage and the resistive or IR voltage which is given by the equation (8).
(8)
V =V +αΔT
total IR
Generally the resistive voltage has a negligible effect on the Seebeck voltage portion of the
total voltage. Therefore to minimize the Seebeck effect contribution to measure the IR voltage,
the measurement process should be processed very fast, for example in 2 seconds or 3
seconds. By switching the current direction the Seebeck voltage can be cancelled out using
the averaging technique, as shown in equation (9).

+ −
[V(I )+αΔT]−[V(I )+αΔT]
V =
(9)
IR
+ -
where I and I are positive and negative current direction, respectively.
This is why AC or fast-switching DC shall be used for measuring the electrical resistivity of
2 2
thermoelectric materials. Typical sample size will be (2 × 2) mm or (3 × 3) mm for
measuring. The measuring procedure shall follow these steps:
a) Cool the Cu block to be used for heat sink
b) Place the end side of sample on the heat sink block
c) Attach the other side of sample to the heater
d) Join the 4-point probe which can regulate the distance between the voltage measuring
probes on the sample
e) Apply AC or fast-switching DC to the sample
f) Apply the heat to the sample
g) Read out the voltage
h) Change the current direction and wait 2 seconds or 3 seconds
i) Measure again the steps from (e) to (g)
4.3 Thermal conductivity measurement
4.3.1 General
Measuring thermal conductivity is very difficult for thin films. Generally thin films have been
fabricated by various physical vapour deposition processes. Therefore in-plane thermal
conductivity and perpendicular thermal conductivity are very different in their characteristics.
Therefore, in order to measure the thermal conductivity of the thin film, the effect of
anisotropy and the possibility of determination of in-plane and perpendicular thermal
conductivity have been considered. Figure 4 shows the principle of in-plane thermal
conductivity of the thin film on the substrate. It is difficult to remove the influence of the
substrate effect when the perpendicular thermal conductivity has been measured. Therefore
in order to obtain a higher accuracy of thermal conductivity, the product of thermal
conductivity and the thickness of the film is greater than that of the substrate. Measuring the
thermal conductivity the thermal conductivity can be calculated using the heating power, as
given by equation (10).
P
k= (10)
db[T(x)−T(x+ I)]/I
– 12 – IEC 62830-2:2017 © IEC 2017
Reflector
T T
(x) (x+I)
I
Heater,
T or T
1 1(t)
Heat sink, T
Film
Film
Heating power,
iwt Radiation
Substrate
P or P α e
Reflector
IEC
Figure 4 – Schematic diagram of measuring in-plane thermal
conductivity of thin film on the substrate
4.3.2 Transient 3ω method
The concept of the transient 3ω method is very similar to the 4-point prove method. The point
patterns for which contact proves for positive and negative voltage and current are connected
by a thin strip metal line have width b which can be used for heaters and thermometers. When
a sinusoidal current with angular frequency ω heats the sample applied, the thin metal strip
line acts as a thermometer. At 3ω the voltage oscillation can be obtained by the resistance
oscillation at 2ω and at excitation current at ω. Finally the thermal conducti
...