Proton irradiation qualification of the vSWIR InGaAs imaging sensor for the VEM and VenSpec-M instruments on VERITAS and EnVision

Abstract

The first NASA spacecraft to visit and explore planet Venus since the 1990s will be the Venus Emissivity, Radio science, InSAR, Topography, And Spectroscopy mission (VERITAS) orbiter. The Venus Emissivity Mapper (VEM) onboard the spacecraft is designed for surface mapping of Venus within dedicated atmospheric spectral windows. The instrument will provide global coverage for the detection of thermal emissions like volcanic activity, surface rock composition, water abundance, cloud formation and their dynamics by observing 14 narrow filter bands in the near-infrared to short-wave infrared (NIR, SWIR) range of 790 nm to 1510 nm. An almost identical instrument will be part of ESA's recently announced EnVision mission to Venus, the VenSpec-M in the Venus Spectroscopy Suite (VenSpec). The utilized photodetector for both missions will be an InGaAs type imaging sensor with integrated thermoelectric (TE) cooling, comprising a 640x512 pixel array with 20 µm pixel pitch. In general, a space environmental qualification of electronic devices combines its susceptibility to radiation induced single event effects (SEE) and the evaluation of permanent degradation effects due to total ionizing dose (TID) and displacement damage dose (DDD). Following a successful qualification test with heavy-ions focusing on SEE, our imaging sensor was subject to a proton irradiation test campaign at Helmholtz-Zentrum Berlin (HZB) for combined TID and DDD testing. To track the sensor evolution, we subdivided the proton fluence into 10 irradiation steps with intermediate measurements.The collected data provide information on the evolution of dark current, light sensitivity and pixels showing randomtelegraph-noise (RTN) on the sensor during a 5-year mission.