Evaluation of solid-state detectors for ultraviolet radiometric applications

The realization and dissemination of ultraviolet spectral responsivity scales at the 0,1% level require a solid-state detector with a predictable, and preferably an invariant, spectral responsivity. Unfortunately, the most widely used detectors for the ultraviolet, silicon photodiodes, have a spectral responsivity that varies rapidly in the ultraviolet due to multiple ionization and recombination effects. This paper describes the properties of alternative wide-bandgap photodiodes such as GaAsP and GaP, together with specially developed detectors based on SiC. These devices are ''solar blind'' to various degrees, thus offering significant advantages over silicon photodiodes in certain applications. Measured quantum efficiency for all these types of photodiode is presented, together with an evaluation of permanent and short-term changes in quantum efficiency of the detectors following exposure to UV radiation.