| This work describes the determination of both internal and external quantum efficiency, QE, of unbiased silicon photodiodes (p+-n) to be used as a light detection element in the trap detectors, which are in general used as the optical responsivity transfer standard. The internal QE values of silicon photodiodes and of trap detectors were calculated from experimentally measured responsivity and reflectance values with an uncertainty at the order of 10-3 and 10-4 %. By applying a QE model that is based on the photodiodes electrical parameters like recombination velocity, diffusion length, diffusion coefficient, absorption coefficient, etc. the internal QE values were extrapolated to 400-1100 nm range. The variations in reflectance and responsivity due to the surface non-homogeneities of photodiodes were also analysed and their effects on QE were calculated approximately at the order of 10-4 %. |
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