Development of a Large Scale Stressed Ge:Ga Detector Array for SAFARI

We report on the development of a large format stressed gallium doped germanium (Ge:Ge) array for the SAFARI instrument. Building on flight proven PACS heritage, the goal of our development is a 32 pixel stressed Ge:Ga module enabling a 32 × 32 pixel photoconductor array for the wavelength range between 110 and 210 μm. The unprecedented size of this array would allow the use of almost all of the 3.8 × 3.8 arcmin field of view provided for SAFARI in the SPICA focal plane. We are currently in the process of manufacturing the individual components of the 32 pixel demonstration module. This prototype module will feature three selectable read out architectures enabling the evaluation and optimisation of the detector performance as well as a two stage multiplexer to distribute the dissipative heat load on the temperature levels provided by the satellite. Thermal modeling has shown that the heat loads are in compliance with the thermal budgets of the SPICA cryogenic system. The ultimate development goal with optimised read out circuits is an NEP of 1 × 10-18 W/Hz1/2, which would present a factor of 8 improvement in the noise performance compared to the PACS stressed Ge:Ga array