Cd1-yZnyTe single crystal is the current material of choice to be used as substrate for the growth of lattice-matched Hg1-x CdxTe epilayers with cutoffs wavelengths in the SWIR range (~2,9 μm (x=0,4) to 2μm (x=0,54)). For the manufacturing of large 2k² IR focal plane arrays with a 15 μm pitch, large diameter Cd1-yZnyTe ingots with a state-of-the-art material quality are required. Crystal growth method from the melt; like Vertical Gradient Freeze technique; enables us to get close to 5 inches in diameter, high quality single crystals, after decades of developments. As the growth of high-quality Cd1-yZnyTe single crystal ingots remains a big technological challenge, we present some recent technical achievements in this field, got within the frame of the H2020 ASTEROID project. Some requirements regarding material specification, like Cd1-yZnyTe substrate size, geometrical perfection (TTV, faces parallelism), material quality (crystallinity, dislocations) have imposed many new process updates and developments in our elaboration scheme. State-Of-the-Art 72x73 mm² Cd1-yZnyTe substrates with epiready surface preparations are now available for the Front-End-Of-Line of 2k² IR Focal Plane Array Processing at CEA-LETI / LYNRED (previously named SOFRADIR).
This LETI/Sofradir/Defir study aims at realizing sub-10 μm pitch HgCdTe infrared FPAs. To cope with the different diode process issues related to pitch reduction-morphologic realization, short-circuits, FTM optimization - a parametric study was carried out - contact size, passivation properties, doping levels, diode processing conditions-. A wafer-level test campaign was conducted to evaluate the process window. It revealed functional MWIR diodes from 15 μm to 3 μm pitch. 7.5 μm pitch 640×512 and 5 μm pitch 64×152 FPA were characterized and turned out to be functional.