4×288 readouts and FPAs properties

Abstract

Analysis of four types 4×288 designed and manufactured readouts is presented. All the readouts have the direct injection input circuit with the circuits incorporated that allows testing procedure of readouts without the photodiodes attached to readout circuits. TDI registers have three delay elements between neighbouring inputs. Some characteristics of 4×288 FPAs with mercury-cadmium-telluride (MCT) arrays are presented too. Analysis have shown that in spite of different constructions of four readout types, different numbers of outputs and external service, rather similar parameters of FPAs have been obtained. Detectivity values measured for all 4×288 FPAs at operation temperature T ≈ 78 K with skimming mode included and background temperature Tb ≈295 K were in the range D*λ ≅ (1.2−1.7)×1011 cmHz1/2/W.

Uncooled Detectors Challenges for THz/sub-THz Arrays Imaging

“…Several input circuits of the readouts can be applied for these detectors in arrays [28], and the most used are direct or buffered direct injection circuits. The typical sensitivity of IR cooled photodiodes is S V~5 ⋅10 7 V/W, S I~5 A/W (T~80 K) reaching NEP~1.5⋅10 −14 W/Hz 1/2 when converting data of detectivity D*≈2⋅10 12 cm⋅Hz 1/2 /W (for 8-11 μm region, 4×288 arrays [24]). For another typical uncooled IR detectors (VO x microbolometers) for 8-14 μm spectral range (ν~30 THz), NEP~10 −12 W/Hz 1/2 , and S V~2 ⋅10 4 V/W.…”

“…Compared to IR imaging arrays for 8-12 μm spectral region, this NEDT value is lower as, e.g., for 4×288 photodiodes array cooled down to T=80 K the value of NEDT can reach NEDT≈10 mK (see, e.g. [24]). …”

HgCdTe Heterostructures Grown by MBE on Si(310) for Infrared Photodetectors

“…The IRFPAs of the 288 × 4 format were provided with a silicon multiplexer possessing an original scheme and special design, the distinctive features of which are the fully digital control via parallel and serial interfaces, possibility of deselecting any defect cell, bidirectional scanning of pixels, and possibility of testing the analog parameters. The multiplexer was manufactured using a commercial 1-m CMOS technology with two metal and two poly-Si levels [Sizov et al, 2006]. The gate and spacer oxide layers were 40 and 90 nm thick, respectively, with the corresponding specific capacitances of 8.65 ×10 -4 and 3.8 ×10 -4 pF/ m 2 .…”

Linear HgCdTe IR FPA 288×4 with bidirectional scanning

“…Six−inch boron−doped p−type <100> Si wafers with the resistivity of 12 W´cm have been taken for the process [14]. The under−gate dielectric was a thermally grown SiO 2 layer with the thickness about 200-400 and the specific capacitance of about 17.2×10 -4 -8.65 pF/μm 2 , depending on foundry−manufacturer.…”