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IEC TR 60747-5-12
Edition 1.0 2021-10
TECHNICAL
REPORT
colour
inside
Semiconductor devices –
Part 5-12: Optoelectronic devices – Light emitting diodes – Test method of LED
efficiencies
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IEC TR 60747-5-12
Edition 1.0 2021-10
TECHNICAL
REPORT
colour
inside
Semiconductor devices –
Part 5-12: Optoelectronic devices – Light emitting diodes – Test method of LED
efficiencies
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.080.99 ISBN 978-2-8322-1035-9
– 2 – IEC TR 60747-5-12:2021 © IEC 2021
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative reference . 8
3 Terms and definitions . 8
3.1 General terms and definitions . 9
3.2 Terms and definitions relating to the optoelectronic efficiencies . 9
3.3 Terms and definitions relating to measuring the efficiencies . 11
3.4 Terms and definitions relating to measuring current components . 12
3.5 Abbreviated terms . 12
4 LED efficiencies. 13
4.1 General . 13
4.2 Theoretical background of optoelectronic efficiencies . 15
4.3 Separate measurement of various efficiencies . 20
4.4 Requirements for accurate and reliable IQE measurement . 20
4.5 Classification of IQE measurement methods . 21
5 Conventional IQE measurement methods: features and limitations . 22
5.1 Calculation of the LEE . 22
5.2 Temperature-dependent photoluminescence (TDPL) . 22
5.3 Intensity-dependent photoluminescence (IDPL) or simply photoluminescence
(PL) . 23
5.4 Temperature-dependent time-resolved photoluminescence (TD-TRPL) . 26
5.5 Time-resolved photoluminescence (TRPL) . 28
5.6 Time-resolved electroluminescence (TREL) . 34
5.7 Constant ABC model . 39
5.8 Constant AB model . 45
6 Standard IQE measurement method I: TDEL . 46
6.1 Temperature-dependent electroluminescence (TDEL) method . 46
6.2 Temperature-dependent radiant power . 46
6.3 Evaluation of the IQE . 47
6.4 Validity of the TDEL: examples of blue LEDs . 49
6.5 Sequence of IQE determination by the TDEL . 50
6.6 Summary of the TDEL . 51
7 Standard IQE measurement method II: RTRM . 51
7.1 Room-temperature reference-point method (RTRM) . 51
7.2 Recombination coefficients, A, B, and C in semiconductors . 52
7.3 Strategy of the IQE measurement just at an operating temperature . 53
7.4 Theoretical background of the RTRM . 54
7.5 Example of the RTRM . 56
7.6 Comparison of IQEs by the TDEL and the RTRM . 59
7.7 Summary of the RTRM . 60
8 The RTRM versus the TDEL and the constant ABC model: comparisons . 60
9 LED performance issues related to the IQE measurement . 67
9.1 Various LED efficiency measurement . 67
9.2 Radiative and nonradiative currents . 70
9.3 The active efficiency (AE): IQE versus forward voltage . 74
10 Conclusion: test method of optoelectronic efficiencies of LEDs . 80
Bibliography . 81
Figure 1 – Sequence of the efficiency measurements . 20
Figure 2 – Theoretical model for analysing the TRPL experiment . 30
Figure 3 – Schematic TRPL response and its interpretation in terms of various lifetimes . 32
Figure 4 – Temporal responses of the TRPL for three samples . 33
Figure 5 – Fitted results of the measured TRPL response . 34
Figure 6 – Schematic diagram of the pulse current injection. 35
Figure 7 – Square of 1τ as a function of current density for a bias voltage . 39
EL
Figure 8 – Estimated IQE (left axis) and measured EQE (right axis) versus current
density . 39
Figure 9 – Experimental EQE curve of a blue LED . 42
Figure 10 – Normalized EQE curves (solid lines) and experimental data (rectangular
symbols) for different IQE peak values as a parameter for a blue LED emitting at
460 nm . 42
Figure 11 – SRH nonradiative carrier lifetime as a function of the C
τA= 1
( )
SRH
coefficient calculated from Equation (82) . 43
Figure 12 – Experimental EQE curve of a blue LED . 43
Figure 13 – Temperature characteristics of an LED . 47
Figure 14 – IQEs as a function of current at various operating temperatures from room
to cryogenic measured by the TDEL method . 49
Figure 15 – Two different cases of normalized EQE curves as a function of current at
various temperatures . 50
Figure 16 – Sequence of the IQE measurement by the TDEL method . 51
Figure 17 – Comparison between the conventional ABC model and the improved AB
model . 54
Figure 18 – Calculation procedure from a relative EQE curve to an IQE curve with the
RTRM . 54
Figure 19 – IQE calculation procedure as a function of current based on the RTRM. 57
Figure 20 – Example of the IQE calculation based on the RTRM . 59
Figure 21 – Comparison of the IQEs evaluated by (a) the TDEL and (b) the RTRM . 60
Figure 22 – Radiant power versus current of a blue LED sample measured at various
temperatures . 61
Figure 23 – Normalized intensities on linear and log scales measured at various
temperatures . 62
Figure 24 – I-V characteristics at various temperatures . 63
Figure 25 – Calculated a as a function of current for various temperatures. I at
2 ref
300 K is the current giving the minimum value of a in region II. . 64
Figure 26 – IQEs obtained by the RTRM (symbols) and the TDEL (solid lines) at
various temperatures . 64
Figure 27 – Comparison of the IE obtained from a at 300 K (left axis) and the
theoretical IE for constant I (right axis) . 65
leak
Figure 28 – Normalized EQE and the fitting by the constant ABC model . 66
Figure 29 – Ratio of the SRH, radiative, Auger recombination currents to the total
current . 66
– 4 – IEC TR 60747-5-12:2021 © IEC 2021
Figure 30 – Radiant power and forward voltage as a function of forward current . 68
Figure 31 – Calculation of the mean photon energy from the emission spectra . 69
Figure 32 – LED efficiencies as a function of forward current . 70
Figure 33 – Sequence of the radiative and nonradiative current measurements . 72
Figure 34 – IQE and forward voltage as a function of forward current . 72
Figure 35 – Radiative current and forward voltage as a function of forward current . 73
Figure 36 – Nonradiative current and forward voltage as a function of forward current . 73
Figure 37 – Total forward current, radiative current, and nonradiative current plotted as
a function of forward voltage . 74
Figure 38 – Distribution of the IQE and V for 31 blue MQW LEDs . 76
F
Figure 39 – Optoelectronic characteristics of three samples under consideration . 77
Figure 40 – Separated radiative and nonradiative current densities of samples 1 and 2 . 78
Figure 41 – Separated radiative and nonra
...