Wide-band (2.5 - 10.5 µm), high-frame rate IRFPAs based on high-operability MCT on silicon

ABSTRACT We have previously presented results from our mercury cadmium telluride (MCT, Hg 1-x Cd x Te) growth on silicon substrate technology for different applications, including negative luminescence, long waveband and mid/long dual waveband infrared imaging. In this paper, we review recent developments in QinetiQ’s combined molecular beam epitaxy (MBE) and metal-organic vapor phase epitaxy (MOVPE) MCT growth on silicon; including MCT defect density, uniformity and reproducibility. We also present a new small-format (128 x 128) focal plane array (FPA) for high frame-rate applications. A custom high-speed readout integrated circuit (ROIC) was developed with a large pitch and large charge storage aimed at producing a very high performance FPA (NETD ~10mK) ope rating at frame rates up to 2kHz for the full array. The array design allows random addressing and this allows the maximum frame rate to be increased as the window size is reduced. A broadband (2.5-10.5 µm) MCT heterostructure was designed and grown by the MBE/MOVPE technique onto silicon substrates. FPAs were fabricated using our standard techniques; wet-etched mesa diodes passivated with epitaxial CdTe and flip-chip bonded to the ROIC. The resulting focal plane arrays were characterized at the ma ximum frame rate and shown to have the high operabilities and low NETD values characteristic of our LWIR MCT on silicon technology. Keywords: MCT; MCT on Si; high frame rate; infrared