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Image persistence is a major problem in infrared detectors, potentiallyseriously limiting data quality in many observational regimes. The problemmanifests itself as remnant images that can persist for several days after adeep exposure. In this study, the persistence behavior of three 5.3um cutoffH2RGs has been characterised using a low-background cryostat with LED lightsources. Persistence charge de-trapping was measured over several hoursfollowing a wide range of exposure levels and exposure times. This data wasthen analysed to yield charge trapping and de-trapping spectra which presentgraphically the trap density as a function of their time constants. Thesespectra show the detector behavior in a very direct way and offer a naturalmetric for comparing different devices. It is hoped that the trap time constantspectra for each detector can be used in an analysis pipeline to removepersistence artifacts based on the recent exposure history of the detector. Thestudy confirmed that the charge traps responsible for persistence must bepresent in the depletion region of the pixel, however, two trap populationswere revealed. One of these captures charge within milliseconds and thenreleases it over many hours. The second population is less problematic withfairly similar trapping and de-trapping time constants. Large differences inpersistence magnitude and trap spectra have been found even between deviceswith near-consecutive serial numbers. Lower temperatures resulted in lowerpersistence both in terms of total trapped charge and the time taken for thatcharge to decay. Limiting the full-well by reducing pixel bias voltage also hada beneficial effect. Previously proposed mitigation techniques including"global reset de-trapping" and "night light" illumination were tried but foundto be ineffective.

Persistence Characterisation of teledyne H2RG detectors