Filtern
Dokumenttyp
Sprache
- Englisch (2)
Referierte Publikation
- ja (2)
Schlagworte
- Ellipsometry (2) (entfernen)
Analysis methods and instrumentation for obtaining optical parameters and thickness profiles of thin-film samples from spectrophotometric and ellipsometric measurements are presented. Measured samples include thermally grown and evaporated SiO2 on a silicon substrate and a polymer photoresist layer on silicon. Experimental results at multiple sample positions give the thickness uniformity and optical constants of thin films. The thickness results obtained with spectrophotometry and ellipsometry agree within 1 nm for the 300 nm thick layer of SiO2 on silicon. For the 1600 nm thick resist sample the agreement of the measurement methods is within 8 nm. For the sample with a nominally 6000 nm thick layer of SiO2 on silicon, there is a deviation of ~100 nm between the spectrophotometry and ellipsometry results. As an application, the optical parameters of a SiO2 layer on an induced junction silicon photodiode are determined by spectrophotometry and are used to confirm earlier values and uncertainties of the SiO2 refractive index and layer thickness non-uniformity.
Ellipsometry is a useful tool for studying the optical properties of thin films such as photovoltaic devices. We employ Müller matrix ellipsometry to study the thin film photovoltaic material copper indium gallium selenide Cu(In,Ga) Se2 (CIGS), a commercially relevant material with high energy conversion efficiency. Confocal microscopy reveals an rms roughness of 68 nm, which greatly affects the ellipsometry data. Rayleigh-Rice theory is employed to account for the optical properties of the surface roughness in the ellipsometry experiment, and a library search method is used to compare Müller parameters calculated for various CIGS compositions, to the measured data. The Müller parameters calculated with the Rayleigh-Rice model are found to correspond well with the measured data, and a surface roughness of 37nm and a correlation length of 125nm are extracted.