5 May 2008 HgCdTe APD- focal plane array development at CEA Leti-Minatec
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Abstract
We report the latest developments of MW HgCdTe electron initiated avalanche photo-diodes (e-APDs) focal plane arrays (FPAs) at CEA-LETI. The MW e-APD FPAs are developed in view of ultra-sensitive high dynamic range passive starring arrays, active 2D/3D and dual-mode passive-active imaging, which is why both the passive imaging performance and the gain characteristics of the APDs are of interest. A passive mode responsivity operability of 99.9% was measured in LPE and MBE e-APDs FPAs associated with an average NETD=12mK, demonstrating that dual mode passive-active imaging can be achieved with LETI e-APDs without degradation in the passive imaging performance. The gain and sensitivity performances were measured in test arrays and using a low voltage technology (3.3V) CTIA test pixel designed for 3D active imaging. The CTIA and test arrays measurements yielded comparable results in terms of bias gain dependence (M=100 at Vb=-7V), low excess noise factor (=1.2) and low equivalent input current (Ieq_in<1pA). These results validated the low voltage CTIA approach for integrating the current from a HgCdTe e-APD under high bias. The test array measurements demonstrated a relative dispersion below 2% in both MBE and LPE e- APDs for gains higher than M>100, associated with an operability of 99%. The operability at Ieq_in<1pA at M=30 was 95%. A record low value of Ieq_in=1fA was estimated in the MBE e-APDs at M=100, indicating the potential for using the MW e-APDs for very low flux applications. The high potential of the MW e-APDS for active imaging was demonstrated by impulse response measurements which yielded a typical rise time lower than 100ps and diffusion limited fall time of 900ps to 5ns, depending on the pixel pitch. This potential was confirmed by the demonstration of a 2ns time of flight (TOF) resolution in the CTIA e-APD 3D pixel. The combined photon and dark current induced equivalent back ground noise at f/8 with a cold band pass filter at λ=1.55μm was 2 electrons rms for an integration time of 50ns.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Johan Rothman, Gwladys Perrais, Eric De Borniol, Pierre Castelein, Nicholas Baier, Fabrice Guellec, Michael Tchagaspanian, Philippe Ballet, Laurent Mollard, Sylvain Gout, André Perez, Maryse Fournier, Jean-Paul Chamonal, Philippe M. Tribolet, Gerard Destefanis, "HgCdTe APD- focal plane array development at CEA Leti-Minatec", Proc. SPIE 6940, Infrared Technology and Applications XXXIV, 69402N (5 May 2008); doi: 10.1117/12.780447; https://doi.org/10.1117/12.780447
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