Recent improvements in silicon photodiode fabrication technology have resulted in the production of photodiodes which are stable after prolonged exposure to short wavelength radiation and which have efficiencies in the far ultraviolet close to those predicted using a value of 3.63 eV for electron-hole pair production in Si. Quantum efficiency and stability data are presented in the 6-124-eV region for several variations on the basic successful design and on devices with extremely thin silicon dioxide antireflecting/passivating layers. The results indicate that the oxide is dominant in determining many of the performance parameters and that a stable efficient far ultraviolet diode can be fabricated by careful control of the Si-SiO(2) interface quality.

Total Reflection X-ray Fluorescence (TXRF) using Synchrotron Radiation from the Stanford Synchrotron Radiation Laboratory (SSRL) has been used to study Al impurities on Si wafer surfaces. For primary excitation energies below the Si K absorption edge an inelastic resonance scattering due to resonant xray Raman scattering is observed. This scattering dominates the background behavior of the Al K fluorescence line, and consequently limits the achievable sensitivity for detection of Al surface contaminants. The energy-and angle-dependence of the resonant x-ray Raman scattering has been investigated to determine the experimental conditions for which the highest sensitivity for Al can be achieved. We find that for a precise determination of the achievable sensitivity, the specific shape of the continuous Raman background has to be taken into account. Our calculations demonstrate a minimum detection limit for Al of 6 x 10 9 atoms/cm 2 for a 10,000 second count time.

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We describe the present capabilities and future plans for soft X-ray optics characterization at the NIST storage ring, SURF II. The existing facility is made up of a monochromator and a reflectometer capable of characterizing the reflectivity of soft X-ray devices, including multilayers, gratings and grazing incidence optics. This system can also be used to characterize the transmission of components such as filters. The present capabilities include a wavelength range from 80 Å to 600 Å. The reflectometer will handle components up to several cm in diameter and its detector can be scanned in two independent angular directions. This allows the mapping of scattered photons from the sample, as well as the measurement of reflectivity as a function of angle and wavelength. Results of measurements on users' samples will be shown. We plan to modernize and expand the capabilities of this facility in the following ways: (1) Construct a new monochromator capable of scanning wavelengths from 30 Å to greater than 600 Å. (2) Construct a new reflectometer with independent, computer-controlled angular and translational motion for the sample and detector. This will permit automated wavelength scans and Θ/2Θ scans at fixed wavelengths, as well as mapping of the sample surface. The reflectometer will have a multidetector capability. It will also allow the measurement of optical constants of thin films. (3) Construct an optical test bench for characterizing the imaging properties of focusing optics. Other considerations for expanded capabilities, depending on the needs of the soft X-ray user community, include: (1) In-situ deposition of thin films with a vacuum transfer capability. (2) Provisions for other types of characterization, such as scanning tunneling microscopy (STM) and interferometric profilometry.