The recently completed upgrade of the Synchrotron Ultraviolet Radiation Facility (SURF III) at the National Institute of Standards and Technology (NIST) has improved the accuracy of radiometric measurements over a broad spectral range from the infrared to the soft x-ray. The beamline 4 at SURF III is a cryogenic-radiometer based radiometric facility for the deep ultraviolet (DUV) spectral range. The upgrade of SURF III has allowed us to use beamline 4 to improve the detector spectral power responsivity scales in the wavelength range from 125 nm to 320 nm. The achieved combined relative standard uncertainty is better than 0.5% over most of this spectral range. This is a significant improvement over the more than 6% relative standard uncertainty in this spectral range of the current scales maintained at the Spectral Comparator Facility (SCF) and the Far UV calibration facility using plasma sources in the Electron and Optical Physics Division. The new DUV scale of beamline 4 was subsequently intercompared and transferred to the SCF and to the Far UV calibration facility to improve their DUV scales and ensure consistency within NIST. We also used beamline 4 to characterize a number of different types of photodiodes using the new scale. Among the photodiodes measured the nitrided silicon photodiodes showed improved spatial response uniformity and radiation stability compared to current SCF UV working standards. We are in the process of replacing current SCF UV working standards with the nitrided silicon photodiodes. The new scale established at beamline 4 improves NIST's calibration capabilities for environmental monitoring, astrophysics, and the UV industry. The new scale also includes wavelengths such as 193 nm and 157 nm, which are of particular interest for the semiconductor photolithography industry.
Citation: Review of Scientific Instruments
Issue: No. 5
Pub Type: Journals
cryogenic radiometer, detector standards, electrical substitution, radiometry, responsivity, synchrotron radiation, UV detector