Optical analysis of doped PbTe samples using UV- VIS and IR ellipsometry

Lead-tin telluride alloy, Pb1-xSnxTe, is a narrow band gap group IV–VI semiconductor with NaCl-like crystalline structure. This material has interesting electronic properties, which makes it suitable for designing infrared photo detectors, diode lasers, and thermo-photovoltaic energy converters. In this project, we used spectroscopic ellipsometry in the spectral range of 0.74–6.5 eV to probe the linear optical response of Pb1-xSnxTe alloys in terms of the complex dielectric function. A strong optical response in the range of 0.7-2.0 eV arising from optical absorption was found. We studied eleven different samples of Pb1-xSnxTe of p-type origin with x values in the range (0 ≤ x ≤ 1)…


Chapter 1. Introduction
1.1 PbTe as an important material for electronic application
1.2 The Measuring Parameter
2. Optical properties
2.1 The complex dielectric function ε
2.2 The complex index of refraction
2.3 The absorption coefficient α
2.4 Polarization
3. Reflection
3.1 The Fresnel’s equations as important parameters
3.2 Optical modeling
3.3 The Cauchy model
4. Ellipsometry
4.1 Definition and theory of ellipsometry
4.2 Available ellipsometers
i. VASE-2
4.3 Sample preparation
4.4 BaF2 as a Substrate
4.5 Experimental
4.6 Fourier Transform Infrared ellipsometry
4.7 Electronic Energy Band Structure
5. Results and discussion
5.1 Comparing results of SE and Infra-red ellipsometry
5.2 Conclusion
Appendix I
Appendix II


Source: Linköping University

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