The band structure of Hg1-xCdxTe results in an electron avalanche photodiode (e-APD) that exhibits single carrier, deterministic, noiseless gain. Data and analysis on 5μm cutoff, Hg0.7Cd0.3Te e-APD gated-imaging arrays with sub-photon sensitivity will be presented.

1. ABSTRACT Photon detectors and focal plane arrays (FPAs) are fabricated at DRS from HgCdTe and silicon in many varieties. 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). 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 1024 2 ) 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 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. 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. NEI σ/μ = 3.0 % was measured with 100 % operability when running the array

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.

Excellent high-operating-temperature infrared photodiodes in the medium-wavelength infrared spectral band with cutoff wavelengths ∼5 μm at 77 K were fabricated on Hg1−xCdxTe samples (x∼0.30) prepared by liquid-phase epitaxy in a tellurium-melt reactor. The samples were doped with indium to ∼1×1014 cm−3 and gold to ∼5×1015 cm−3. Thick planar diodes (∼80 μm thick) and thin cylindrical diodes (∼10 μm thick) of the n-on-p type were fabricated, and they gave comparable, excellent detector dark values within a factor of two. At 130 K, dark currents as low as 5×10−7 A/cm2 were obtained.