High-sensitivity high-stability silicon photodiodes for DUV, VUV and EUV spectral ranges

In this paper, the optical and electrical performance of a newly developed silicon photodiode based on pure boron CVD technology (PureB-diodes) is introduced. Due to their extremely shallow p-n junction, with the depletion zone starting only a few nanometers below the surface, and nm-thin pure-boron-layer coverage of the anode surface, PureB-diodes have so far demonstrated the highest reported spectral responsivity in all sub-visible ultraviolet (UV) ranges: DUV (deep ultraviolet), VUV (vacuum ultraviolet) and EUV (extreme ultraviolet), covering a spectrum from 220 nm down to few nanometersMoreover, the measured responsivity at 13.5 nm wavelengths (EUV) approaches the theoretical maximum (~0.27A/W). PureB-diodes also maintain excellent electrical characteristics, with saturation-current values typical for high-quality silicon diodes, and a high breakdown voltage. Experimental results have demonstrated the extremely high radiation hardness of PureB-diodes when exposed to high EUV radiant exposures in the order of a few hundred kJ/cm2. No change in the responsivity is observed within the experimental uncertainty. In the more challenging DUV and especially VUV ranges, PureB-diodes demonstrate a slight initial drop of responsivity (1 to 2%), after which they stabilizes their performance.

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