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DRS Sensors & Targeting Systems, under contract to the Space Dynamics Laboratory of Utah State University, is providing the focal plane detector system for NASA's Wide-field Infrared Survey Explorer (WISE). The focal plane detector system consists of two mercury cadmium telluride (MCT) focal plane module assemblies (FPMAs), two arsenic doped silicon (Si:As) Blocked Impurity Band (BIB) FPMAs, electronics to drive the FPMAs and report digital data from them, and the cryogenic and ambient temperature cabling that connect the FPMAs and electronics. The MCT and Si:As BIB focal plane arrays (FPAs) utilized in the WISE FPMAs are both megapixel class indium-bump hybridized devices fabricated by Teledyne Imaging Systems and DRS Sensors & Targeting Systems, respectively. This paper reports performance of the WISE Si:As BIB FPAs that are used for the WISE 12- and 23-μm wavelength bands.

DRS uses LPE-grown SWIR, MWIR and LWIR HgCdTe material to fabricate High-Density Vertically Integrated Photodiode (HDVIP) architecture detectors. 2.5 μm, 5.3 μm and 10.5 μm cutoff detectors have been fabricated into linear arrays as technology demonstrations targeting remote sensing programs. This paper presents 320 x 6 array configuration technology demonstrations' performance of HDVIP HgCdTe detectors and single detector noise data. The single detector data are acquired from within the 320 x 6 array. Within the arrays, the detector size is 40 μm x 50 μm. The MWIR detector array has a mean quantum efficiency of 89.2% with a standard deviation to mean ratio, σ/μ = 1.51%. The integration time for the focal plane array (FPA) measurements is 1.76 ms with a frame rate of 557.7 Hz. Operability values exceeding 99.5% have been obtained. The LWIR arrays measured at 60 K had high operability with only ~ 3% of the detectors having out of family response. Using the best detector select (BDS) feature in the read out integrated circuit (ROIC), a feature that picks out the best detector in every row of six detectors, a 320 x 1 array with 100% operability is obtained. For the 320 x 1 array constituted using the BDS feature, a 100% operable LWIR array with average NEI value of 1.94 x 1011 ph/cm 2/s at a flux of 7.0 x 1014 ph/cm2/s has been demonstrated. Noise was measured at 60 K and 50 mV reverse bias on a column of 320 diodes from a 320 x 6 LWIR array. Integration time for the measurement was 1.76 ms. Output voltage for the detectors was sampled every 100th frame. 32,768 frames of time series data were collected for a total record length of 98 minutes. The frame average for a number of detectors was subtracted from each detector to correct for temperature drift and any common-mode noise. The corrected time series data was Fourier transformed to obtain the noise spectral density as a function of frequency. Since the total time for collecting the 32,768 time data series points is 98.0 minutes, the minimum frequency is 170 μHz. A least squares fit of the form (A/f + B) is made to the noise spectral density data to extract coefficients A and B that relate to the 1/f and white noise of the detector respectively. In addition noise measurements were also acquired on columns of SWIR detectors. Measurements were made under illuminated conditions at 4 mV and 50 mV reverse bias and under dark conditions at 50 mV reverse bias. The total collection time for the SWIR detectors was 47.7 minutes. The detectors are white noise limited down to ~10 mHz under dark conditions and down to ~ 100 mHz under illuminated conditions.

This paper describes direct photon counting data on several pixels of the Rockwell SSPM detector array, about which absolute single photon detection efficiencies and time responses were reported previously by Kwiat et al. The new data shows a substantially larger efficiency, 85%, and suggests that damage in the optical fiber employed in the earlier data was responsible for the lower number, 70%. When the results of this paper are analyzed using reasonable assumptions, one concludes that several improvements of the SSPM detector are still possible to bring the photon counting efficiency close to or larger than 95%.

A solid-state photomultiplier (SSPM) capable of continously detecting individual photons of wavelength between 0.4 and 28 microns has recently been disclosed (Petroff et al., 1987). The initial response of the SSPM to single photon is a fast, high-amplitude current pulse of between 10,000 and 100,000 electrons. A phenomenological model of the SSPM avalanche process is presented which successfully predicts the shape of the observed pulse-amplitude distribution by including small history-dependent effects on the carrier transport. The model clarifies the consequences of the electric field strength and the scattering of the electrons for the development of the avalanche in the SSPM.

Infrared absorption spectroscopy measurements have been made on Cu doped and nominally undoped CdTe at He temperatures and in the frequency range of 200–4000 cm−1. For Cu doped samples a well‐resolved fine structure superimposed on a broad maximum, apparently related to Cu, is observed in the absorption spectrum between 1000–1500 cm−1 at 5 K. Several sets of sharp transitions are seen to recur regularly at an interval of 171 cm−1, corresponding to the LO phonon energy. Each set contains sharp lines separated by a constant energy of 30 cm−1, corresponding to TA phonon energy. The temperature dependence of the spectrum is consistent with multiphonon‐assisted transitions. The intensity of lines at a given temperature scales almost linearly with the concentration of Cu in the sample. The sharpness of the lines suggests atomic transitions. Another interesting feature, apparently not related to the above sharp structure, is observed in some of the undoped samples in the far infrared range of 200–500 cm−1. In th...

Blocked-Impurity-Band (BIB) extrinsic silicon (Si:As) detectors have demonstrated high sensitivity and quantum efficiency in the long wavelength infrared (LWIR) spectral region (to 28 microns) as well as wide frequency response, low optical crosstalk, nuclear radiation hardness, and stable, predictable performance. Furthermore, it has been demonstrated that SWItched mosFET (SWIFET) multiplexers provide a low noise readout approach for use with BIB detectors. This paper describes the state-of-the-art of multiplexed BIB detector hybrid focal plane arrays (HFPAs). The principle of operation and performance of optimized BIB and Back Illuminated BIB (BIBIB) detectors are presented. The SWIFET multiplexer, including necessary circuitry for BIBIB detector readout, has been designed and fabricated using a newly developed process for cryogenic (

One- and two-dimensional arrays of solid-state photomultipliers, based on arsenic-doped silicon, capable of counting individual photons of wavelength between 0.4 and 28 microns have been demonstrated.

A postdispersion system for astronomical observations with Fourier transform spectrometers in the thermal infrared has been developed. Postdispersion improves the sensitivity of radiation noise limited observations by reducing the spectral range incident on the detector. The instrument is described and various uses are discussed.