A method and system for testing the complex conductivity of epitaxial thin film materials in the terahertz frequency range

Abstract

The present disclosure relates to the technical field of thin film material performance detection, and provides a method and system for testing complex permittivity of epitaxial thin film material in a terahertz frequency band, which comprises the following steps: performing transmission type testing on different transmission regions obtained by dividing a to-be-tested epitaxial thin film material sample and air, to obtain a time-domain waveform of a terahertz pulse transmission electric field; performing Fourier transform on the obtained time-domain waveform to obtain an amplitude spectrum and a phase spectrum of the electric field; calculating a complex refractive index of a substrate material according to the amplitude spectrum and the phase spectrum; constructing a transmission and reflection model for the substrate plus the epitaxial thin film material by taking into account multiple reflections inside the substrate material; obtaining a relationship between the complex permittivity of the epitaxial thin film material and the complex refractive index of the substrate material based on the transmission and reflection model, and inversely calculating the complex permittivity of the epitaxial thin film material. In the process of testing the complex permittivity of the epitaxial thin film material, the testing error introduced by multiple reflections inside the substrate material is taken into account, thereby improving the testing accuracy of the complex permittivity of the material.

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