Investigation of the stability of the spectral responsivity of silicon photodiodes
Five different types of silicon photodiode were monitored for a four-year period by one laboratory and for two years by three other laboratories and ageing rates were calculated. These varied widely between types of photodiode. The lowest ageing rates were found in the two photodiodes that were hermetically sealed, the Centronic and Hamamatsu photodiodes. However, other measurements made at NPL on similar devices without windows have shown similar stabilities, suggesting that for these photodiode types, a hermetically sealed window is not essential for stability. The other devices showed significant ageing rates particularly at shorter wavelengths, but these could be reduced by storing the devices in a desiccator. None of the measurements carried out as part of the selection tests gave a reliable prediction of ageing rate. However, high shunt impedance did lead to improved linearity. Both Centronic and Hamamatsu photodiodes have a linear response over a wide dynamic range and a highly uniform spectral responsivity across their sensitive area. They are well suited for use as spectral responsivity transfer standards over the specified spectral region at least at the few tenths of a percent uncertainty level, and probably at even lower levels in the visible region of the spectrum.
Bibliographic Reference: EUR 13485 EN (1991) 63 pp., MF, ECU 4, blow-up copy ECU 8.75
Record Number: 199110705 / Last updated on: 1994-12-02
Original language: en
Available languages: en