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Terahertz time-domain spectroscopic ellipsometry: instrumentation and calibration
Mohammad Neshat1, N P Armitage
1Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA. mneshat@jhu.edu
Optics Express
|December 25, 2012
Summary
We developed a new terahertz time-domain spectroscopic ellipsometry (THz-TDSE) setup and calibration. This advanced technique enhances material characterization by accurately measuring thin films and substrates.
Area of Science:
- Optics and Photonics
- Materials Science
- Spectroscopy
Background:
- Terahertz time-domain spectroscopic ellipsometry (THz-TDSE) is an emerging characterization technique.
- Existing THz-TDSE setups often require realignment for different geometries and angles of incidence.
- Accurate calibration is crucial for compensating instrumental non-idealities.
Purpose of the Study:
- To introduce a novel, versatile instrumentation and calibration procedure for THz-TDSE.
- To enable arbitrary angle of incidence measurements in reflection and easy configuration for transmission geometry.
- To demonstrate a new calibration scheme for improved accuracy in THz-TDSE.
Main Methods:
- Developed a THz-TDSE setup with a flexible angle of incidence (15°-85°) in reflection and easy switch to transmission.
- Utilized hollow core photonic band gap fiber for femtosecond laser delivery to a THz photoconductive antenna detector without pre-chirping.
- Adapted a regression algorithm from optical ellipsometry for calibrating the THz-TDSE system, compensating for detector and polarizer non-idealities.
Main Results:
- Successfully demonstrated the new instrumentation and calibration procedure for THz-TDSE.
- Characterized high resistivity silicon, opaque silicon, and a few-micron-thick thermal oxide on silicon using the developed setup.
- Obtained accurate ellipsometric parameters at various angles of incidence in reflection geometry.
Conclusions:
- The presented THz-TDSE instrumentation and calibration procedure offer enhanced versatility and accuracy for material characterization.
- The novel setup and calibration method are suitable for analyzing various semiconductor materials and thin dielectric films.
- This work establishes a robust platform for advanced THz-TDSE applications.
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