Ultraviolet stability of silicon photodiodes

The ultraviolet (UV) instability of silicon photodiodes is a very complex p henomenon. The change in spectral responsivity after UV exposure can depend on the level of irradiance and total radiant exposure, duration of exposur e, wavelength of the UV radiation, the type of photodiode, and the way the photodiode was stored and used before UV exposure. For a systematic investi gation, the responsivity change must be determined not only at the waveleng th of UV exposure but throughout the whole spectral range in which the phot odiode is used. Obviously, a fast method is needed to perform corresponding measurements over a wide range of parameters. Therefore a new, fast and ac curate technique based on Fourier-transform spectroscopy was used to study the UV stability of silicon photodiodes in detail. Results are presented fo r different types of silicon photodiodes (Kamamatsu S1337 and S5227 diodes, a novel PtSi-n-Si Schottky photodiode, and UVG and AXUV photodiodes from I nternational Radiation Detectors).