Development of infrared detectors for space astronomy

Space astronomy requires infrared detector focal plane arrays (FPAs) with high quantum efficiency, low dark current, low power dissipation, and background limited noise performance. As one of the most advanced cryogenic space telescopes, the Space Infrared Telescope Facility (SIRTF), which is planned to be launched in the year 2001, will use two {dollar}256times 256{dollar} hybrid InSb photodiode arrays in its 1-5 {dollar}rmmu m{dollar} bands and two Si:As arrays in its 5-10 {dollar}rmmu m{dollar} bands running at {dollar}rm{lcub}sim{rcub}15K.{dollar} For the next generation space telescopes, HgCdTe double layer planar heterostructure (DLPH) detectors are good candidates for the 5-10 {dollar}rmmu m{dollar} bands and {dollar}rm {lcub}sim{rcub}30K{dollar} operation.; In this thesis, a new readout circuit (multiplexer or mux) designed for SIRTF InSb detector arrays was evaluated and its operation parameters were optimized. Different mux processes were evaluated and the best materials were selected. Various experiments were designed and performed to systematically test the InSb focal plane arrays (FPAs) according to the SIRTF requirements. The noise performance was also modeled to compare with the experimental results. Some FPA flaws were found and analyzed and the information was actively fed back to Santa Barbara Research Center for improvements in the manufacturing procedures. The InSb detector arrays so developed have met most of the SIRTF requirements. For long wavelength HgCdTe detectors, a new method was developed to measure the I-V curves of 10 {dollar}rmmu m{dollar} cutoff DLPH detectors made by the LPE and MBE methods. Dark current mechanisms were modeled to compare with the experimental results. The dependence of dark current on temperature and bias was analyzed to determine the dominant mechanisms. At the temperatures relevant for space astronomy, around 30 K, trap-to-band tunneling was found to be the dominant dark current mechanism. Several strategies were adopted or proposed to minimize this source of dark current. The developed HgCdTe detectors are very promising for the future passively cooled long wavelength space telescope.