Extension of a silicon-based detector spectral-responsivity scale into the ultraviolet

Abstract

A detector spectral-responsivity scale based on the intrinsic properties of radiometric-quality photodiodes has previously been established over the wavelength range 400 nm to 900 nm. Work to extend this range into the ultraviolet below 400 nm is now being carried out. The new scale, which covers the 250 nm to 900 nm range, can be held in new four-element and five-element trap detectors. The precision of the scale in the ultraviolet is limited principally by the greater variations - across the detector surface and from one detector to another - of the internal quantum efficiency at these wavelengths. The actual internal quantum efficiency of S1337-11 Hamamatsu photodiodes obtained by our measurements is compared with previous experimental and calculated values for the quantum yield of silicon in this wavelength region.