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Research Equipment
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Spectroscopic Ellipsometry

  UV-Vis-IR Vertical Ellipsometer


This commercially-built, fully automated ellipsometer provides high precision measurements of the optical properties of any sample over the wavelength range of 190 to 1700 nm. An integrated light source/ monochrometer designed specifically for the system provides an exceptionally bright, well collimated probe beam over the entire wavelength range. An autoretarder allows both transparent and opaque samples to be measured with equal accuracy, and also is the key element for the generalized ellipsometry mode, which can determine the optical properties of anisotropic samples with arbitrary orientation. The ellipsometer can be combined with the cryostat systems (providing variable temperature measurements from 4.2 to 700 K), or combined with an computer-controlled electromagnet (providing automated magneto-optic measurements over the entire wavelength range).

  UV-Vis-IR Convertible Ellipsometer


Essentially identical to the Vertical UV-Vis-IR system, this ellipsometer can be mounted on various ex-situ or in-situ systems to accommodate measurements of horizontal sample surfaces such as liquids. It also provides highly accurate broadband (190 - 1700 nm) measurements for all of our insitu systems. With lenses attached, the light beam for this system also can be focused onto a 20 m m-wide area.

  Broadband Infrared Ellipsometer


This infrared ellipsometer provides state-of-the-art measurements of the optical properties from 1.25 to 40 um. The rotating compensator configuration produces excellent data from both transparent and opaque samples, and the system can accommodate samples sizes from less than ¼ inch to 8 inches wide. This is a very difficult instrument to produce: currently, there are perhaps a few dozen wide-band infrared spectroscopic ellipsometers in the world, fewer than five of those reside in the United States. Only two or three other instruments in the world can match the wavelength range and accuracy of this ellipsometer. This commercially designed and built instrument is also an extremely stable, robust workhorse that can be (and often is) operated 24 hours a day, seven days a week. The instrument is designed to accommodate both variable temperature cryostats. Future improvements include an upgrade to a generalized ellipsometry configuration that can handle anisotropic samples of arbitrary orientation.

  Far Infrared Ellipsometer


A detector consisting of a liquid helium cooled silicon bolometer provides this infrared ellipsometer with a maximum signal-to-noise ratio in the wavelength range of 14 to 100 um. When combined with the Janis cryostat, this instrument is designed measure the far infrared response of samples in the temperature range of 4.2 to 700 degrees Kelvin. Using the same software and many of the same hardware components as the Broadband IR ellipsometer, this specialized instrument fully integrates into our data analysis system. Its generalized ellipsometry configuration allows measurements of anisotropic samples of arbitrary orientation.

  Magneto-optic Far Infrared Ellipsometer


This unique system consits of a superconducting magnet cryostat (6 T) connected to a customized far infrared generalized ellipsometer configuration for measurements in the wavelength range of 14 to 100 um. It is the first experimental system which allows the measurement of the optical Hall-effect in the far infrared frequency range. Thereby, the anti-symmetric dielectic function tensor can be measured and the free-charge-carrier parameters determined in a single optical experiment. The setup furthers allows the measurement of the far infrared response of samples in the temperature range of 4.2 to 300 degrees Kelvin. (The system is operated in cooperation with the University of Leipzig, Germany.)

  Multiwavelength Ellipsometer


Multiwavelength ellipsometers acquire full spectra (all available wavelengths) of ellipsometric data very rapidly. Though their spectral range is usually somewhat limited compared to the ex-situ ellipsometers, they are especially well-suited for monitoring of materials growth and processing. Obtaining the time dependence as well as the wavelength dependence of the optical response significantly improves the ability to determine sample optical properties and film thicknesses. Existing facilities make it possible for these instruments to monitor processes on both sputtering systems, the electron beam evaporation chamber, the LEO simulation chamber, a UV exposure station and a electrochemical process chamber. This flexibility strongly enhances our research capability in many different types of material systems and processes.
The analysis of these data presents special problems associated with the complexity of the information obtained; however, the inferences which may be drawn are often quite extensive if the experiments are properly designed and data properly analyzed.
The rate of technology advancement within these systems is steep; the number of wavelengths for which data may be obtained has, for instance, advanced from 12 to about 250 in the last five years. Other comparable advancements are being made in data in the area of data quality. In fact, recent contributions to system design by researchers in the CMOMR have aided the development of the M2000, the first of a new generation of multi-wavelength ellipsometers. These feature higher data precision for a wider variety of samples. The facility also possesses an 88-wavelength version (M88), which also provides in-situ monitoring of optical properties from the mid-UV through the visible wavelength regime.

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