• Beaglehole Instruments Picometer Ellipsometer
  • capable of both spectroscopic and single wavelength measurements with variable angle of incidence
  • Unique modulator design makes it independent of temperature variations
  • high sensitivity typically equivalent to an ellipticity of about 10-5, or to a polarisation angle of 10-3 degrees at a time constant of 1 s. This is equivalent to a detection limit of less than 10-12m of oxide on the silicon surface (about 1/100 of a monolayer)
  • Gold substrates can be prepared for deposition of organic films for study
  • Please see the Measurement tab for examples of the applications of this instrument.

     

    Technical Specification

     


    Light Source
    Single wavelength: He/Ne laser
    Spectroscopic: quartz halogen lamp (> 400 nm) or Xe Arc lamp (> 200 nm)
    Polarisers calcite crystal that can be switched at 1.5 Hz to eliminate offsets
    Birefringence Modulator 3 component high stability design, susprasil optical element with transmission to 200 nm, 50 kHz modulation frequency
    Detector End-on photomultiplier with gain control that can be set to track a preset DC current for large intensity variations
    Beam Size 1 mm Diameter or larger depending upon light source.
    Table Ultra high rigidity table with incident and reflection arms in vertical plane. Arms separately driven by stepping motors with angular resolution of 1/20 degrees. Table allows rotation of arms through 360. Closest angle between arms 20. 140 mm free diameter in center of table. XYZ adjustable sample mount
    Electronics Dual analog lock-in amplifier at 50 kHz and 100 kHz frequencies provides simultaneous reading of Re(r) and Im(r)
    Sensitivity Im(r), Re(r) < 10-5 at 1 s response time (reflection from glass).
    Sensitivity is reduced at shorter time constants (variation is roughly proportional to t-1/2)
    Speed The Fastest response time is 1 ms
    Computer Control Software implemented as extension to the IgorPro data analysis package by WaveMetrics running on Windows 2000. A Microcontroller acts as hardware interface and data logger for true real-time operation. The control software allows simultaneous instrument control and on-line data analysis.
    Data Analysis Simulations of ellipticity are provided for layers on substrates, as a function of angle of incidence, layer thickness, substrate and film optical anisotropy.SCI Film Wizard is also available for modeling ellipsometric data.