Center for Advanced Research and Technology :: University of North Texas

CART Facilities

High-Resolution Analytical Scanning Transmission Electron Microscope (S/TEM) Variable-Angle Spectroscopic Ellipsometer

A J.A. Woolam variable angle spectroscopic ellipsometer (VASE) was acquired by CART in 2006.

This instrument is used to characterize surfaces, thin films, and microstructure through the use of polarized light. Some of the material properties that can be determined are optical constants, film thicknesses, doping concentration, surface and interfacial roughness, alloy ratio, crystallinity, and optical anisotropy.

Instrument Specifications

Measurement Capabilities

Reflection and Transmission Ellipsometry
Generalized Ellipsometry (Anisotropy, Retardance, Birefringence)
Reflectance (R) and Transmittance (T) intensity
Cross-polarized R/T
Depolarization
Scatterometry
Mueller-matrix

Data Acquisition Rate

Typical: 0.1 to 3 seconds per wavelength, depending on reflectivity of sample.
High Accuracy: measurements using full AutoRetarder capability require 20 seconds per wavelength.

System Configuration

Rotating Analyzer Ellipsometry (RAE) with patented AutoRetarder®. Automated wavelength selection via monochromator.

Spectral Range

250-1100nm (single chamber standard)
240-1100nm (double chamber standard)
DUV extension to 193nm
NIR extension to 1700nm
XNIR extension to >2200nm
XXIR extension to 2500nm

Temperature Control

Cryostat and heating stage for variable temperature studies from 4.2 Kelvin to 600° C.

Angle of Incidence

Fully Automated
Range: 15°-90° (standard system)
Accuracy: 0.01°

Liquid Cell Electrochemical Cell

Add cell with optical windows for measurement through liquid ambient. Allows characterization of liquid/solid interface

Mapping

Provides computer controlled or manual XY mapping of samples of various sizes. Automated sample alignment is also available. Software can automate both acquisition and analysis, as well as plot 3-D graphs.

Further Options