Arvind DSouza, (DRS Sensors & Targeting Systems), M.G. Stapelbroek (DRS Sensors & Targeting Systems), E. Atkins (DRS Sensors & Targeting Systems), H. Hogue (DRS Sensors & Targeting Systems), J. Reekstin (DRS Sensors & Targeting Systems), H-D Shih (DRS Infrared Technologies), M. Skokan (DRS Infrared Technologies), M. Kinch (DRS Infrared Technologies), J. Robinson (DRS Infrared Technologies)
Keywords: Telescopes, Instrumentation
Abstract:
Photon detectors and focal plane arrays (FPAs) are fabricated from HgCdTe and silicon in many varieties. DRS LPE-grown SWIR, MWIR and LWIR HgCdTe material fabricated in the High-Density Vertically Integrated Photodiode (HDVIP) architecture has been focused primarily on high background systems applications with great success. Remote sensing applications, however, may need to operate under both high and low background conditions. HgCdTe HDVIP FPAs have been measured under a variety of flux conditions and at several operating temperatures. In addition, DRS manufactures silicon detectors and FPAs that cover the spectral range from visible to the very-long-wavelength infrared (VLWIR). Detectors are manufactured that exhibit high internal gain to allow photon counting over this broad spectral range. Large-format, VLWIR FPAs based on doped-silicon Blocked-Impurity-Band (BIB) detectors have been developed. FPAs with Si:As BIB arrays have been made in a variety of pixel formats (up to 10242) and have been optimized for low, moderate, and high infrared backgrounds.
DRS uses LPE-grown SWIR, MWIR and LWIR HgCdTe material to fabricate High-Density Vertically Integrated Photodiode (HDVIP) architecture detectors. 2.5 ?m, 5.3 ?m and 10.5 ?m 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 ?m x 50 ?m. The MWIR detector array has a mean quantum efficiency of 89.2 % with a standard deviation to mean ratio, ??? = 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.
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 ?Hz. 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. In addition, 256 x 256 MWIR arrays have been measured at 78K. Operability values exceeding 99.5 % have been obtained.
Data will also be presented on a variety of silicon products. Arsenic-doped silicon (Si:As) BIB detector arrays with photon response out to about 28 ?m, and Antimony-doped silicon (Si:Sb) BIB arrays having response to wavelengths > 40 ?m have been demonstrated. Avalanche processes in Si:As at low temperatures (~ 8 K) have led to two unique solid-state photon-counting detectors adapted to infrared and visible wavelengths. The infrared device is the solid-state photomultiplier (SSPM) capable of counting VLWIR photons (? ? 28 ?m) with high quantum efficiency. A related device optimized for the visible spectral region is the visible-light photon counter (VLPC). The VLPC is a nearly ideal device for detection of small bunches of photons with excellent time resolution. Finally, DRS makes imaging arrays of pin-diodes utilizing the intrinsic silicon photoresponse to provide high performance over the 0.4 1.0 ?m spectral range operating near room temperature. pin-diode arrays are particularly attractive as an alternative to charge-coupled devices (CCDs) for space applications where radiation hardening is needed.
Date of Conference: September 10-14, 2006
Track: Telescopes and Instrumentation