The tolerance of a hybrid array (HA) to total ionizing dose (TID) radiation continues to be a major performance consideration for space based imaging systems. In an effort to improve TID performance, HA manufacturers have begun to utilize circuit design techniques to enhance the TID tolerance of readout integrated circuits (ROICs). This paper will report on the radiometric and TID radiation characterizations of a HA that utilizes radiation-hardened-by-design (RHBD) techniques. This paper will not describe the design techniques used. Instead, characterization data are presented that demonstrate a HA TID tolerance of over 25 units of total ionizing dose (UTID). This result is compared with the performance of devices with ROICs processed at commercial foundries that do not make use of RHBD techniques. The HA described in this paper represents a state-of-the-art device; the ROIC was designed to be low noise, high gain, and radiation tolerant. While design techniques were utilized to enhance its TID hardness, no special fabrication processes were used.

This paper presents a study of the performance degradation in a proton environment of long wavelength infrared (LWIR) HgCdTe detectors. The energy dependence of the Non-Ionizing Energy Loss (NIEL) in HgCdTe provides a framework for estimating the responsivity degradation in LWIR HgCdTe detectors due to on-orbit exposure from protons. Banded detector arrays of different detector designs were irradiated at proton energies of 7, 12, and 63 MeV. These banded detector arrays allowed insight into how the fundamental detector parameters degraded in a proton environment at the three different proton energies. Measured data demonstrated that the detector responsivity degradation at 7 MeV is 5 times larger than the degradation at 63 MeV. Comparison of the responsivity degradation at the different proton energies suggests that the atomic Columbic interaction of the protons with the HgCdTe detector is likely the primary mechanism responsible for the degradation in responsivity at proton energies below 30 MeV.

Remote sensing applications make use of the optical polarization characteristics of a scene to enhance target detection and discrimination. Imaging polarimeters typically utilize polarizing arrays located in front of a focal plane array as a means of extracting polarization information from the optical scene. Over the last few years, technology development efforts have resulted in FPAs that integrate the polarizer with the infrared focal plane array (FPA). This paper will report on the radiometric and polarization characterization of a micro-grid polarizer FPA from DRS Infrared Technologies, L.P. (DRS). These measurements were performed to evaluate the radiometric performance and the polarization characteristics of the FPA.

The results of total ionizing dose and proton fluence characterization of hybrid Si P-i-N focal plane arrays are reported. The focal plane arrays consist of a silicon P-i-N detector array bump bonded to 128 x 128 CMOS readout integrated circuit (ROIC). The FPAs were characterized in total ionizing dose and proton fluence radiation environments. Full radiometric characterizations were performed at each radiation dose level to determine the impact of the radiation on dark current, noise, responsivity, sensitivity, and dynamic range. Results from the total ionizing dose experiment demonstrate an unexpected increase in the visible P-i-N detector dark current. The median dark current increased more than two orders of magnitude from pre-radiation to 300 krad(Si) and the magnitude of the dark current was found to be a strong function of detector bias. No appreciable change in responsivity or noise was observed for wavelengths above 400 nm up to a total ionizing dose of 750 krad(Si). Results from the proton radiation experiment show no appreciable change in responsivity was observed up to a 63 MeV proton fluence of 3 x 10 12 protons/cm 2 (400 krad(Si) of total ionizing dose). The median dark current increased approximately two orders of magnitude, but even at this higher level, the dark current did not contribute significantly to the median noise at an integration time of 10 ms. The dominant degradation mechanism, in both the total ionizing dose and proton fluence environments, is an increase in dark current in the Si P-i-N detectors.