Spectroscopic Ellipsometry

Spectroscopic ellipsometry has long been recognized as a powerful technique to characterize thin films and multilayer structures. It is now routinely used for non-destructive on-line characterization of semiconductor process. SOPRA, leader in commercial spectroscopic ellipsometer for research and development, has already developed an infrared ellipsometer as an option on visible instrument to provide the largest wavelength range available up to now (from deep UV 190 nm to far infrared up to 18 micrometers ). A new design of the instrument is presented here which includes a small spot size to get ride of the problems of back face reflection on silicon wafers, and an improved signal /noise ratio to allow rapid measurements compatible with an industrial environment. Some examples of application concerning dopant density in epilayers and composition of low k dielectrics are presented.

The lack of optical constants information for hybrid perovskite of CH 3 NH 3 PbBr 3 in thin films form can delay the progress of efficient LED or laser demonstration. Here, we report on the optical constants (complex refractive index and dielectric function) of CH 3 NH 3 PbBr 3 perovskite thin films using spectroscopic ellipsometry. Due to the existence of voids, the refractive index of the thin films is around 8% less than the single crystals counterpart. The energy bandgap is around 2.309 eV as obtained from photoluminescence and spectrophotometry spectra, and calculated from the SE analysis. The precise measurement of optical constants will be useful in designing optical devices using CH 3 NH 3 PbBr 3 thin films.

Dielectric function of disorder in single-crystalline silicon (c-Si) implanted by He with energy of 40keV and fluences from 1×1016 to 1×1017cm−2 were determined around the E1 and E2 critical points (CPs) by spectroscopic ellipsometry. The implanted material was modeled by an effective medium composition of c-Si and damaged Si. The dielectric function of damaged Si was calculated using the model

The purpose of this article is to present a new broadband Mueller ellipsometer designed to work in the
mid-infrared range, from 3 to 14 μm. The Mueller ellipsometer, which can be mounted in reflection or in
transmission configuration, consists of a polarization state generator (PSG), a sample holder, and a
polarization state analyzer (PSA). The PSG consists of one linear polarizer and a retarder sequentially
rotated to generate a set of four optimal polarization states. The retarder consists of a biprism made of
two identical Fresnel rhombs disposed symmetrically and joined by an optical contact, giving the ensemble
a “V” shape. Retardation is induced by the four total internal reflections that the beam undergoes
when it propagates through the biprism. Total internal reflection allows the generation of a quasiachromatic
retardation. The PSA is identical to the PSG, but with its optical elements mounted in reverse
order. After a measurement run, the instrument yields a set of sixteen independent values, which is the
minimum amount of data required to calculate the Mueller matrix of the sample. The design of the
Mueller ellipsometer is based on the optimization of an objective criterion that allows for minimizing
the propagation of errors from raw data to the Mueller matrix of the sample. The pseudo-achromatic
optical elements ensure a homogeneous quality of the measurements for all wavelengths. The performance
of the Mueller ellipsometer, in terms of precision and accuracy, is discussed and illustrated with
a few examples.