DESIGN AND PERFORMANCE OF A VUV ELLIPSOMETER

Spectroscopic ellipsometry provides a rapid, precise and direct measurement of both real and imaginary parts of the dielectric function from bulk materials and thin films. The technique is used routinely in the NIR-VIS-UV spectral region to determine the optical constants of solids over the photon energy range 1.5-5.0 eV. By making use of synchrotron radiation with its high degree of linear polarization and triple-reflection polarizers we have built a new automated instrument which extends the spectral range of spectroscopic ellipsometry up to 35 eV. Our instrument is ideal for investigating the band structure of wide-band-gap semiconductors and insulators and can also be used to measure the excitonic structures arising from transitions from shallow core levels. In this paper the design of the instrument is described and the factors that limit the ultimate performance are analyzed. © 1990.