Pixel source follower glow in HxRG detector

Abstract

The Atmospheric Remote‐Sensing Infrared Exoplanet Large‐survey (ARIEL) space mission is dedicated to the study of the exoplanets' atmosphere. To do so, the payload module is made of two instruments. The ARIEL InfraRed Spectrometer instruments is one them, it will perform spectroscopic measurements from the near‐infrared domain to the long‐wave infrared domain. The instrument relies on the use of two H1RG detectors. During early phases of instrument development dark current measurements have been done on an 8 m cutoff detector operated in window mode. These measurements revealed an unexpected level of dark current. This observation triggered a joint series of tests at the European Space Agency technical center and at the Astrophysics Department of the Atomic Energy Commission. As demonstrated in this paper, the excess of dark current originates from the collection, by the photosenstive layer, of light emitted by the source follower transistor of the pixel unit cell. This effect is referred as glow. Based on experimental results, this glow is studied as a function of the detector operating conditions (temperature, biases, timing diagram). These results also show that for the range of operating temperatures considered, the dark current performance of the detector is limited by the glow.