SALES - Information SERVICE - Information CONTACT
Dr. Peter Thiesen - Senior Application Specialist Accurion

Dr. Peter Thiesen

Senior Application Specialist

Phone: +49-551-9996020

Mail: pt@accurion.com

Daniela Bogner - Sales Manager Accurion

Daniela Bogner

Sales Manager

Phone: +49-551-9996013

Mail: db@accurion.com

Linda Thieme - Sales Manager Accurion

Linda Thieme

Sales Manager

Phone: +49-551-9996016

Mail: lth@accurion.com

Sebastian Funke - Application Specialist, 2D Materials Accurion

Sebastian Funke

Application Specialist, 2D Materials

Phone: +49-551-999600

Mail: sfu@accurion.com

Christian Röling - Application Specialist, Sample Measurements Accurion

Christian Röling

Application Specialist, Sample Measurements

Phone: +49-551-999600

Mail: cr@accurion.com

Dr. Christian Hoffmann - Application Specialist for Biological Applications Accurion

Dr. Christian Hoffmann

Application Specialist for Biological Applications

Phone: +49-551-9996021

Mail: cho@accurion.com

Stephan Ferneding - Chief Executive Officer Accurion

Stephan Ferneding

Chief Executive Officer

Phone: +49-551-999600

Mail:

Greg Hearn - Technical Sales Manager Accurion

Greg Hearn

Technical Sales Manager

Phone: +1-408-966-3171

Mail: gh@accurion.com

Narayana Sharma - Sales and Application Accurion

Narayana Sharma

Sales and Application

Phone: +91-98450 04273

Mail: sharma@accurion.com

Frank Zuo - Sales and Application Accurion

Frank Zuo

Sales and Application

Phone: +86-21 5017 9099

Mail: fz@accurion.cn

Dr. Antonio Gonzalez - Service and LB-Application Specialist Accurion

Dr. Antonio Gonzalez

Service and LB-Application Specialist

Phone: +49-551-9996035

Mail: ago@accurion.com

Arash Mirhamed - Product Manager Accurion

Arash Mirhamed

Product Manager

Phone: +49-551-9996015

Mail: am@accurion.com

Holger Grube - Service Engineer Accurion

Holger Grube

Service Engineer

Phone: +49-551-9996023

Mail: hog@accurion.com

SALES / SUPPORT
Logo

Spectroscopic ellipsometry

Spectroscopic ellipsometry Accurion

Spectroscopic Ellipsometry

The term “spectroscopic ellipsometry” refers to ellipsometric measurements that are carried out at various wavelengths of the incident beam. With spectroscopic ellipsometry, an experiment provides not just one set of Δ & Ψ but it gives a large set of these ellipsometric angles as a function of photon energy. This allows for the characterization of complex multilayer systems even when several physical parameters are unknown, and for the measurement of a material’s dielectric function in a thin film layer. Due to its great versatility, spectroscopic ellipsometry is an established technique in modern thin film analytical labs, and in quality control for industrial fabrication.

Spectroscopic Ellipsometry in Detail

Thick layers, complex materials and multilayer systems usually cannot be characterized by using single wavelength ellipsometry. The more unknown parameters are included in an optical model, the more independent sets of Δ & Ψ are needed to perform reliable numerical fitting of the wanted parameters. Spectroscopic ellipsometry yields enough information from the sample to make modelling feasible even when several physical parameters of the sample have to be determined. Common spectroscopic ellipsometers apply broadband light sources that cover the visible range (VIS) and parts of both the ultraviolet (UV) and the near infrared (NIR) range of the electromagnetic spectrum.

Study of Complex Structured Samples Using Spectroscopic Ellipsometry

In many cases, the optical constants of the materials included in a complex sample are known as a function of photon energy and can be loaded into an optical model from a database. Spectroscopic ellipsometry then gives access to structural parameters of complex samples.

Typical fields of applications are:

• multilayer stacks with more than one unknown layer thickness

• a single thick film layer (up to 1 µm layer thickness) where Δ & Ψ are ambiguous in the case of single wavelength ellipsometry

• characterization of volume fractions or compositions of binary material layers via effective medium theories (e.g. Bruggemann effective medium approximation (EMA), Lorentz-Lorenz model, Maxwell-Garnett model):

    • surface roughness

    • material-void volume fraction, e.g. in a layer of nanoparticles

    • alloy compositions

Simultaneous Measurement of Material and Structural Parameters with Spectroscopic Ellipsometry

Furthermore and in contrast to single wavelength ellipsometry, spectroscopic ellipsometry simultaneously gives access to both the optical constants and layer thickness of a thin film layer.

This achieved by applying so called dielectric function models (e.g. Tauc-Lorentz model, Cauchy model, or Drude model) that assume a functional relationship between the material’s complex (electric) permittivity ε and the vacuum wavelength λ (or equivalent photon energy) of the probing light. Each function model has a certain small number of free parameters whose values are obtained from numerical optimization of the optical model that is chosen for the sample. The relationship N=√ε then yields the complex refractive index N that is defined as N=n+ik with the refractive index n and the extinction coefficient k.

Deduction of Physical Parameters Based on Dielectric Function Modeling with Spectroscopic Ellipsometry

As Spectroscopic ellipsometry gives access to a thin film layer’s dielectric function ε(λ), it may also be used to obtain physical parameters that can be deduced from the material’s dielectric function that was obtained via dielectric function modeling. Typical examples in the UV, VIS, and NIR range are:

• characterization of electronic band gap in the UV and VIS range (Tauc-Lorentz model)

• free carrier absorption in the NIR (Drude model)

More about imaging-ellipsometry.

CONTACT
© Accurion GmbH 2017