J. A. Woollam introduces the alpha 2.0, the second era of the alpha-SE, which was first developed in 2003 and was created to offer researchers with an ellipsometer that was budget-friendly, dependable, strong, and correct for routine measurements of movie thickness and refractive index.
Picture Credit score: Quantum Design
Through the years, enhancements have been added to the alpha-SE; including a number of angles of incidence, adjusting the optical format for improved information high quality, and including equipment. Nevertheless, the underlying know-how remained constant. The alpha-SE was a step-scan, rotating-compensator instrument, which suggests a stepper motor strikes the compensator to a place and holds it there whereas information is collected, then it strikes to the following place, and so forth. The step-scan method met Woollam’s targets of being strong, dependable and correct, nevertheless it wanted to be sooner. As well as, the alpha-SE used a 3rd celebration spectrometer as a part of the polarisation state detector. Though the detector wasn’t purpose-built for the ellipsometer, it carried out effectively and nonetheless does a wonderful job.
After a future, Woollam thought it was time to boost the underlying know-how. The results of these updates is the alpha 2.0, which options the patented dual-rotation know-how and thus joins the iSE and theta-SE ellipsometers.
These devices are all a part of the budget-friendly choices, every designed for a selected market: the alpha 2.0 is for analysis prospects, the iSE for in-situ purposes, and the theta-SE for patrons with uniformity mapping wants.
J. A. Woollam Firm
The twin-rotation know-how makes use of a rotating compensator earlier than the pattern and a rotating analyser after the pattern. With dual-rotation, the instrument captures polarisation data from a number of optical orientations, which at all times gives high-accuracy measurements. The alpha 2.0 additionally gives 23 parts of the Mueller matrix in a single optical cycle, which means Mueller matrix measurements may be obtained rapidly with out “stitching” a number of measurements collectively.
The brand new design of the alpha 2.0 additionally incorporates most of the options that made alpha-SE an amazing instrument, beginning with the value. Woollam made certain to offer prospects with a budget-friendly ellipsometer that’s dependable, strong and correct.
One of many primary differentiators between the alpha-SE and alpha 2.0 is the spectrometer, which is constructed on 35+ years of expertise in spectrometer design for ellipsometry.
J. A. Woollam Firm
The alpha 2.0 makes use of a QTH gentle supply together with CCD detection to offer data over the seen spectral vary with 190 wavelengths between 400 and 1000 nm. The thickness and refractive index may be decided for quite a lot of pattern sorts, from easy clear movies to semi-absorbing movies and anisotropic supplies.
With quick measurement speeds and push-button operation, the alpha 2.0 is right for qualifying clear skinny movies.
Single-layer dielectrics on silicon or glass substrates may be measured in seconds. Log outcomes for easy-to-use comparisons in each graphical and tabular codecs.
Most of the mechanical features of the instrument stay the identical. For these aware of the alpha-SE, you’ll discover the alpha 2.0, for probably the most half, seems to be the identical. That is largely as a result of Woollam are persevering with with the manually adjusted multi-angle functionality to be a helpful function as a result of it allows sensitivity to materials parameters for multi-layer stacks and complicated supplies, together with absorbers and anisotropic supplies. The extra sensitivity is, partially, derived from the change in path size that happens at every angle as gentle travels by the movie, as outlined by Snell’s regulation. The multi-angle idea gives a profit for the extra complicated samples.
Pattern alignment options stay comparable. With the alpha 2.0, the pattern can merely be positioned on the stage, and the sign will likely be maximised previous to measurement with no user-required changes. The aim within the design translated to an easy, quick, and dependable measurement course of. Like its predecessor, the alpha 2.0 is a benchtop instrument with a small footprint, measuring 476 mm (width), 324 mm (depth), and 311 mm (top). It’s light-weight and requires lower than 1 amp at 100/240 VAC, so it must be simple to position on a lab desk.
