Free-space microwave measurement of permittivity of epitaxial layer semiconductor

A free-space method for the calculation of complex permittivity of epitaxial layer on doped and undoped substrates measured by a spot-focusing measurement system have been developed. The effective dielectric constants obtained were close to the published values. The method used was Metal-Backed Method, where S
₁₁
is measured. The samples are sandwiched between Teflon plate which is quarter wavelength at mid-band frequency and backed by a metal plate. Simulations of the measurement setup were carried out using Computer Simulation Technology (CST) and the effective dielectric constants are compared with measurements. Results are reported in the frequency range of 18-26 GHz.