Interaction between microwaves and semiconductor wafer-mirror structure

The interference of microwaves in a structure composed of a weakly absorbing wafer, an air gap, and a mirror has been analyzed in a contact less fashion with a view to determining conductivity inhomogeneities in the wafer thickness. It is demonstrated that measuring the reflection coefficient of such a structure at a certain wavelength and an air gap values makes it possible to find the approximate values of the Fourier expansion coefficients of the wafer.