BSI PD IEC TR 60747-5-12:2021
$215.11
Semiconductor devices – Optoelectronic devices. Light emitting diodes. Test method of LED efficiencies
| Published By | Publication Date | Number of Pages |
| BSI | 2021 | 92 |
This technical report discusses the terminology and the measuring methods of optoelectronic efficiencies of single light emitting diode (LED) chip or package without phosphor. White LEDs for lighting applications are out of the scope of this part.
This technical report provides guidance on
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terminology of optoelectronic efficiencies of single LED chip or package without phosphor, such as the power efficiency (PE), the external quantum efficiency (EQE), the voltage efficiency (VE), the light extraction efficiency (LEE), the internal quantum efficiency (IQE), the injection efficiency (IE), and the radiative efficiency (RE) [1]1;
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test methods of optoelectronic efficiencies of the PE, the EQE, the VE, the LEE, and the IQE [1];
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review of various IQE measurement methods reported so far in view of accuracy and practical applicability;
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the measuring method of the LED IQE based on the temperature-dependent electroluminescence (TDEL) [2];
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the measuring method of the LED IQE based on the room-temperature reference-point method (RTRM) [3];
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the measuring method of the radiative and nonradiative currents of an LED [4];
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the relationship between the IQE and the VE, which leads to introduction of a new LED efficiency, the active efficiency (AE) as AE = VE × IQE.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 2 | undefined |
| 4 | CONTENTS |
| 7 | FOREWORD |
| 9 | INTRODUCTION |
| 10 | 1 Scope 2 Normative reference 3 Terms and definitions |
| 11 | 3.1 General terms and definitions 3.2 Terms and definitions relating to the optoelectronic efficiencies |
| 13 | 3.3 Terms and definitions relating to measuring the efficiencies |
| 14 | 3.4 Terms and definitions relating to measuring current components 3.5 Abbreviated terms |
| 15 | 4 LED efficiencies 4.1 General |
| 16 | Tables Table 1 – LED items and their measuring methods listed in IEC 60747-5-6:2016 |
| 17 | 4.2 Theoretical background of optoelectronic efficiencies |
| 21 | Table 2 – Summary of efficiency items defined in IEC 60747-5-8:2019 |
| 22 | 4.3 Separate measurement of various efficiencies 4.4 Requirements for accurate and reliable IQE measurement Figures Figure 1 – Sequence of the efficiency measurements |
| 23 | 4.5 Classification of IQE measurement methods |
| 24 | 5 Conventional IQE measurement methods: features and limitations 5.1 Calculation of the LEE 5.2 Temperature-dependent photoluminescence (TDPL) Table 3 – Various LED IQE measurement methods |
| 25 | 5.3 Intensity-dependent photoluminescence (IDPL) or simply photoluminescence (PL) |
| 28 | 5.4 Temperature-dependent time-resolved photoluminescence (TD-TRPL) |
| 30 | 5.5 Time-resolved photoluminescence (TRPL) |
| 32 | Figure 2 – Theoretical model for analysing the TRPL experiment |
| 34 | Figure 3 – Schematic TRPL response and its interpretation in terms of various lifetimes |
| 35 | Figure 4 – Temporal responses of the TRPL for three samples |
| 36 | 5.6 Time-resolved electroluminescence (TREL) Figure 5 – Fitted results of the measured TRPL response |
| 37 | Figure 6 – Schematic diagram of the pulse current injection |
| 41 | 5.7 Constant ABC model Figure 7 – Square of as a function of current density for a bias voltage Figure 8 – Estimated IQE (left axis) and measured EQE (right axis) versus current density |
| 44 | Figure 9 – Experimental EQE curve of a blue LED 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 |
| 45 | Figure 11 – SRH nonradiative carrier lifetime tsRH ((= 1/A) as a function of the coefficient calculated from Equation (82) Figure 12 – Experimental EQE curve of a blue LED |
| 47 | 5.8 Constant AB model |
| 48 | 6 Standard IQE measurement method I: TDEL 6.1 Temperature-dependent electroluminescence (TDEL) method 6.2 Temperature-dependent radiant power |
| 49 | 6.3 Evaluation of the IQE Figure 13 – Temperature characteristics of an LED |
| 51 | 6.4 Validity of the TDEL: examples of blue LEDs Figure 14 – IQEs as a function of current at various operating temperatures from room to cryogenic measured by the TDEL method |
| 52 | 6.5 Sequence of IQE determination by the TDEL Figure 15 – Two different cases of normalized EQE curves as a function of current at various temperatures |
| 53 | 6.6 Summary of the TDEL 7 Standard IQE measurement method II: RTRM 7.1 Room-temperature reference-point method (RTRM) Figure 16 – Sequence of the IQE measurement by the TDEL method |
| 54 | 7.2 Recombination coefficients, A, B, and C in semiconductors |
| 55 | 7.3 Strategy of the IQE measurement just at an operating temperature |
| 56 | 7.4 Theoretical background of the RTRM Figure 17 – Comparison between the conventional ABC model and the improved AB model Figure 18 – Calculation procedure from a relative EQE curve to an IQE curve with the RTRM |
| 58 | 7.5 Example of the RTRM |
| 59 | Figure 19 – IQE calculation procedure as a function of current based on the RTRM |
| 61 | 7.6 Comparison of IQEs by the TDEL and the RTRM Figure 20 – Example of the IQE calculation based on the RTRM |
| 62 | 7.7 Summary of the RTRM 8 The RTRM versus the TDEL and the constant ABC model: comparisons Figure 21 – Comparison of the IQEs evaluated by (a) the TDEL and (b) the RTRM |
| 63 | Figure 22 – Radiant power versus current of a blue LED sample measured at various temperatures |
| 64 | Figure 23 – Normalized intensities on linear and log scalesmeasured at various temperatures |
| 65 | Figure 24 – I-V characteristics at various temperatures |
| 66 | Figure 25 – Calculated a2 as a function of current for various temperatures. Iref at 300 K is the current giving the minimum value of a2 in region II. Figure 26 – IQEs obtained by the RTRM (symbols) and the TDEL (solid lines) at various temperatures |
| 67 | Figure 27 – Comparison of the IE obtained from a2 at 300 K (left axis) and the theoretical IE for constant Ileak (right axis) |
| 68 | Figure 28 – Normalized EQE and the fitting by the constant ABC model Figure 29 – Ratio of the SRH, radiative, Auger recombination currents to the total current |
| 69 | 9 LED performance issues related to the IQE measurement 9.1 Various LED efficiency measurement |
| 70 | Figure 30 – Radiant power and forward voltage as a function of forward current |
| 71 | Figure 31 – Calculation of the mean photon energy from the emission spectra |
| 72 | 9.2 Radiative and nonradiative currents Figure 32 – LED efficiencies as a function of forward current |
| 74 | Figure 33 – Sequence of the radiative and nonradiative current measurements Figure 34 – IQE and forward voltage as a function of forward current |
| 75 | Figure 35 – Radiative current and forward voltage as a function of forward current Figure 36 – Nonradiative current and forward voltage as a function of forward current |
| 76 | 9.3 The active efficiency (AE): IQE versus forward voltage Figure 37 – Total forward current, radiative current, and nonradiative current plotted as a function of forward voltage |
| 78 | Figure 38 – Distribution of the IQE and VF for 31 blue MQW LEDs |
| 79 | Figure 39 – Optoelectronic characteristics of three samples under consideration Table 4 – Parameters in IQE and current density versus voltage curves |
| 80 | Figure 40 – Separated radiative and nonradiative current densities of samples 1 and 2 |
| 81 | Figure 41 – Separated radiative and nonradiative current densities of samples 1 and 3 Table 5 – Comparison of recombination mechanisms between samples |
| 82 | 10 Conclusion: test method of optoelectronic efficiencies of LEDs |
| 83 | Bibliography |
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BSI PD IEC TR 60747-5-12:2021
Semiconductor devices – Optoelectronic devices. Light emitting diodes. Test method of LED efficiencies Published By…
