Dielectric Permittivity Measurements of Thin Films at Microwave and Terahertz Frequencies.
Abstract: This thesis
focuses on the complex dielectric characterizations of thin film materials using the
state-of-the-art methods at microwave wavelengths and terahertz frequencies. Several
methods are developed and employed. Thin film materials are already used in a variety of
microwave and higher frequency applications such as electrically tunable microwave
devices, integrated circuits li... read moreke MMICs, radomes, and radar absorbing coating. The
determination of the dielectric properties of these films is thus of significant
importance. The measurement of complex dielectric permittivity of thin films is very
difficult at microwave, millimeter, and THz frequencies because both the amplitude
change and phase shift are not large enough to evaluate the real part of the dielectric
permittivity. A specially designed transverse slotted cavity for X-band microwave
measurement has been designed and constructed to employ with a vector network analyzer
to evaluate the real part of dielectric permittivity of thin films accurately and
conveniently. The dispersive Fourier transform spectroscopy (DFTS) with an improved 500
nanometer step mirror movement has been implemented to increase the phase change
determination significantly to characterize the real part of permittivity from about 300
GHz to 700 GHz. Both techniques can record small phase shift caused by the thin film
precisely. Commercially available polymer thin films are measured to validate the
Thesis (M.S.)--Tufts University, 2012.
Submitted to the Dept. of Electrical Engineering.
Advisor: Mohammed Afsar.
Committee: Mohammed Afsar, Douglas Preis, and Joshua Wilson.
Keywords: Electrical engineering, Electromagnetics, and Materials Science.read less