Reference-free THz-TDS conductivity analysis of thin conducting films

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spectroscopy

Background:

• Terahertz time-domain spectroscopy (THz-TDS) is a powerful tool for probing material properties.
• Accurate electrical parameter extraction often requires a time-consuming reference scan.
• Characterizing thin conducting films like graphene is crucial for electronic applications.

Purpose of the Study:

• To develop and validate a reference-free THz-TDS method for determining electrical parameters of thin conducting films.
• To eliminate the need for a separate reference scan in THz-TDS measurements.
• To accurately retrieve frequency-dependent AC conductivity and DC electrical properties of graphene.

Main Methods:

• Utilized steady-state transmission-mode THz-TDS.
• Compared directly transmitted THz pulses with transient internal reflections within the substrate.
• Applied the Drude model to fit the acquired AC conductivity data.
• Investigated the method using two distinct THz spectrometer setups (0.2-1.5 THz and 2-10 THz).

Main Results:

• Successfully acquired frequency-dependent AC conductivity of graphene without a reference scan.
• Retrieved key electrical parameters: DC sheet conductivity, scattering time, carrier density, mobility, and Fermi velocity.
• Demonstrated the method's applicability across different THz frequency ranges.

Conclusions:

• The developed reference-free THz-TDS method provides an efficient and accurate approach for electrical characterization of conducting films.
• This technique simplifies the experimental procedure by removing the necessity of a reference scan.
• The method holds significant potential for rapid material analysis in research and industry.