APD , FPA , HOT , Infrared , large format , MCT , small pixel pitch , SWaP

Recent Progress in MCT detectors in France



The exceptional physical properties of MCT and the maturity of the technology allows today the fabrication of  more and more complex infrared FPAs with this material, keeping the highest performance.

Large arrays with small pitches can be achieved in a large variety of cut of wavelengths such as SWIR, MWIR, LWIR, and VLWIR, including the visible. Pitch reduction has for first consequence an increase of the resolution but is also a major element for consumption reduction.

Thanks to fundamental considerations based on minority carrier lifetime, these FPA present, on suitable technologies, lower and lower dark currents. As a consequence they can operate at higher temperature reducing power consumption and making better reliability of cryogenic systems (SWAP).

New advanced functions can be addressed with more complex design of the pixel such as multicolor detection with MCT hetero-structures grown by MBE, or fast and noiseless amplification in the pixel using avalanche photodiodes (APD), or signal processing with smart readout circuit made with advanced foundries .

This paper gives an overview of the most recent developments at Sofradir and Leti joint laboratory DEFIR on MCT detectors.
First a focus is made on high quality material developments that are the major key for all kind of devices: large CZT single crystals (115mm diameter), large MCT lattice matched epitaxies grown by LPE and MBE.

New developments on planar p on n technology are described on several bands from SWIR to VLWIR. As an illustration, detectors that operate in MWIR band (5.2µm) at high temperature (150K) with a high operability (above 99.5%) are presented together with ultra-low dark current (0.06e/s) SWIR detectors. Other data on TV size LWIR and TV/2 size VLWIR (up to 15µm cut off) will be given in this paper.

Then, MWIR FPA with a pitch of 10µm is presented. This FPA presents excellent performances, opening the way for more compact classical size FPAs (TV) or reasonable size very large FPAs (several millions pixels).

In addition, latest results on advanced technologies as avalanche photodiode and dual band detectors are given. The developments of avalanche photodiodes could lead soon to the fabrication of SWIR APDs able to operate at high temperature.


G. Destefanisa, O. Gravranda, M. Vuillermetb and D. Billon-Lanfreyb,
aCEA Leti-MINATEC, 17 rue des Martyrs – 38054 Grenoble Cedex 9, France
bSOFRADIR, 43-47 rue Camille Pelletan – 92290 Chatenay-Malabry, France