Lock-in Thermography: Basics and Use for Evaluating Electronic Devices and Materials

1. Introduction

2. Physical and Technical Basics

2.1 IR Thermography Basics

2.2 The Lock-in Principle and its Digital Realization

2.3 Lock-in Thermography

2.4 Timing Strategies

2.5 Influence of Non-Harmonic Heating

2.6 Noise Analysis

2.7. Calibration

2.8 Heat Dissipation and Transport Mechanisms in Solar Cells

2.9 Carrier Density Imaging

3. Experimental Technique

3.1 Different (Lock-in) Thermography Realizations

3.2 Commercial Lock-in Thermography Systems

3.3 Illumination Systems

3.4 Solid Immersion Lenses

3.5. Realization of CDI/ILM Systems

3.5.1. Absorption Mode

3.5.2. Emission Mode

3.5.3. Lifetime Calibration

4. Theory

4.1 Influence of the Heat Conduction to the Surrounding

4.2 Temperature Drift Compensation

4.3 Thermal Waves of Point Sources

4.4 Thermal Waves of Extended Sources

4.5 The Quantitative Interpretation of Lock-in Thermograms

4.5.1 The Image Integration / Proportionality Method

4.5.2 Deconvolution of Lock-in Thermograms

5. Measurement Strategies

5.1 Which Signal Should be Displayed?

5.2 Influence of the Lock-in Frequency

5.3 Influence of the IR Emissivity

5.4 Influence of the Peltier Effect

6. Typical Applications

6.1 Integrated Circuits

6.1.1 3D Analysis

6.1.2 IC-Tester Controlled LIT

6.2 Solar Cells

6.2.1 Dark Lock-in Thermography (DLIT)

6.2.1.1 Shunt Imaging

6.2.1.2 High-current DLIT

6.2.1.3 Series Resistance Imaging (RESI)

6.2.1.4 Ideality Factor and Saturation Current Mapping

6.2.1.5 Local I-V curves measured Thermally (LIVT)

6.2.1.6 Reverse-bias DLIT

6.2.1.7 Temperature Coefficient and Slope Imaging

6.2.1.8 DLIT-based J_sc Imaging

6.2.1.9 Local I-V Evaluation

6.2.1.10 LIT and Luminescence Imaging: Comprehensive Loss Analysis

6.2.2 Illuminated Lock-in Thermography (ILIT)

6.2.2.1 V_oc-ILIT

6.2.2.2 J_sc-ILIT

6.2.2.3 R_s-ILIT

6.2.2.4 Avalanche Multiplication Factor Imaging (MF-ILIT)

6.2.2.5 ILIT-Based Efficiency Imaging

6.2.2.6 ILIT-Based J_sc Imaging

6.2.2.7 Suns ILIT

6.2.3 Summary of Solar Cell Applications

6.3 Failure Analysis of Solar Modules

6.3.1 Differential ILIT Techniques

6.3.2 Solar Cell Analysis in Modules (SCAM)

6.4 Spin Caloritronics

6.5 CDI/ILM on Solar Materials

6.5.1 Analysis of Material Evaluation During Processing

6.5.1 Temperature-Dependent Measurements

6.5.3 Trap Density Images from CDI/ILM

7. Summary and Outlook

References

Appendix: Thermal and IR Properties of Selected Materials

List of Symbols

Abbreviations

Index