| 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 like 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 methods. |
