VASE
Product Category: Ellipsometry
Industry: Particle and surface science
Supplier: J A Woollam
Description
Why a VASE?
Maximum Data Accuracy
The VASE features a rotating analyzer ellipsometer (RAE) combined with our patented AutoRetarder® for unparalleled data accuracy.
High Precision Wavelength Selection
The scanning monochromator is designed specifically for spectroscopic ellipsometry. It optimizes speed, wavelength accuracy and light throughput, while automatically controlling selection of wavelengths and spectral resolution.
Flexible Measurements
The VASE features a vertical sample mount to accommodate a large variety of measurement geometries including reflection, transmission, and scattering.
AutoRetarder® Technology
Rotating Analyzer Ellipsometers (RAE) maximize data accuracy near the “Brewster” condition – where Ψ/Δ data are content-rich. However, this region can be limiting for samples with reduced signal. The patented AutoRetarder is a computer controlled waveplate which modifies the light beam polarization before it reaches the sample. This produces optimum measurement conditions for any sample – under any conditions.
AutoRetarder accurately measures:
• Ψ and Δ over the full range!
• Generalized (anisotropic) Ellipsometry
• Depolarization data
• Mueller-matrix data
Optical Coatings
The AutoRetarder® measures Δ accurately even when close to 0° or 180° which helps characterize thin films on transparent substrates, such as glass or plastics. Applications include decorative coatings, anti-reflection and high-reflection layers and stacks, low-emissivity films, electrochromic and photochromic layers and more.
Laser optics
Accurate wavelength selection using monochromator allows measurements at the operating wavelength for optics, e.g. 1550nm, 1310nm, 980nm, 632.8nm, 589nm …
Thin Films
VASE is sensitive to layer thickness down to sub-nanometer. For absorbing layers, the VASE allows measurement of SE and Transmission Intensity (T). When analyzed simultaneously, SE + T often allow determination of n, k, and t. For example, this thin metal layer is only 14 nm thick.
SE + T for thin metal layer.
Semiconductors
Bandgap, electronic transitions and critical points can be measured for semiconductor materials such as GaN, InP, SiGe, CdTe, etc. Good wavelength resolution and ability to measure depolarization insure accurate optical constants.
SiGe optical constants with varying composition.
Photosensitive Materials
The monochromator is positioned before the sample, so only low intensity monochromatic light strikes the sample. This prevents exposure of photosensitive samples.
Optical constants of a photolithography film.
Specifications
| Ellipsometer Configuration | RAE with AutoRetarder | |
| Wavelength Range | Standard (Double Chamber) VASE+DUV VASE+DUV+XNIR VASE+DUV+XXIR VASE+XNIR VASE+XXIR |
240-1700 nm 193-1700 nm 193-2500 nm 193-3200 nm 240-2500 nm 240-3200 nm |
| Number of Wavelengths | User defined before measurement | |
| Angles of Incidence | 15°-90° | |
| Data Acquisition Rate | 0.1 to 3 seconds per wavelength | |
| Max substrate thickness | 20mm | |
Facility Requirements
| Power | 100, 110, 220, 240 VAC, 50-60Hz, 4/8 Amps |
Table to be supplied by end user.
Dimensions
Brochures
Accessories
Camera |
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Add camera with display to view spot location on sample. The light beam may not appear on smooth, specular surfaces.Commonly sold with Standard or Alternate Focusing |
Automated Translation (150x150mm) |
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Translator Size: 150×150 mm XYStandard stage and Translation stage are swappable. |
Automated Translation (50x50mm) |
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Translator Size: 50×50 mm XYIncludes two exchangeable stages.
Open stage with hole for transmission mapping (41×41 mm) Standard stage and Translation stage are swappable. Commonly sold with Alternate Focusing |
Standard Focusing |
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100 or 200 μm beam diameter depending on installed optical fiber.Commonly sold with Camera |
Alternate Focusing |
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200 or 400 μm beam diameter depending on installed optical fiber.Commonly sold with Camera and 50×50 mm Automated Translation. |
Cryostat |
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Temperature range: 4.2 to 500 Kelvin OR 4.2 to 800 KelvinAngle: 70°
Includes UHV chamber/cryostat, turbo pump,and temperature controller. Cryostat can be installed and removed, which allows the user to switch between the standard sample stage and the cryostat. |
Wide-Range Temperature Stage |
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Temperature range: -70°C to 600°CAngle: 70°
Active Cooling with Liquid Nitrogen Sample area 22mm in diameter |
Standard Heat Stage (HTC-100) |
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Temperature range: Room Temp to 300°CAngle: 70°
Passive Cooling Sample area up to 50mm diameter |
Rotation Stage |
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Automated high precision sample rotation (360° Theta-only) stage.Useful when studying anisotropy. Through-hole behind sample allows transmitted beam measurements from normal incidence (0°) to ±19°.
Standard stage and rotation stage are swappable. |
Manual Sample Translation |
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Translator Size: 50×50 mm XYStandard stage and Manual Sample Translation stage are swappable. |
Liquid Prism Cell |
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The liquid minimum deviation cell is used to determine liquid refractive index (n and k) using a hollow prism cell. Measure minimum deviation angles through the liquid filled prism. Two cells are included:
Features Automated Z-Translation |
37mL Electrochemical Cell |
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General purpose liquid cell with vertical mount above liquid line for convenient electrochemical work. |
5mL Vertical Liquid Cell |
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General purpose liquid cell with 5mL volume. |
270µL Vertical Liquid Cell |
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Ultra low-volume liquid cell. (Minimum sample size 8 mm x 21 mm) |
