KEYWORDS: Mid-IR, Long wavelength infrared, Modulation transfer functions, Semiconducting wafers, Medium wave, Crosstalk, Spectral response, Staring arrays, Diodes, Dark current
In 2022, Leonardo UK presented the first results from Condor HD, a 12μm MWIR-LWIR Dual Waveband Infra-Red (DWIR) high-performance infrared detector, grown by Metal Organic Vapour Phase Epitaxy (MOVPE) on GaAs substrates. By using a “back-to-back” diode structure, these pixels are spatially coherent, and changing the bias polarity across the stacked diodes provides sensitivity in the desired waveband (in this configuration MWIR or LWIR).
This paper discusses further characterisation and development of the CMT structure, demonstrating improvement to spectral bandwidth, QE and MW defects. Leonardo UK have also performed further dark current measurements and spectral crosstalk measurements on these new wafer designs.
Direct MTF characterisation (in both the MWIR and LWIR bands) has enabled confirmation that optical crosstalk between neighbouring pixels in-band is equivalent to that seen on single band MWIR and LWIR devices - results of which are reported herein. Retaining the DWB mesa structure also seen on the 24μm Condor II Detector has been key to this.
Having established production capacity for high resolution, small pixel Mid Wave Infra-Red (MWIR) devices down to 8μm; this paper discusses the latest developments at Leonardo UK with 12μm MWIR-LWIR Dual Waveband Infra-Red (DWIR) high-performance infrared detectors, grown by Metal Organic Vapour Phase Epitaxy (MOVPE) on GaAs substrates. As with the 30μm, 24μm and 20μm mesa pixels that Leonardo UK pioneered during the early 2000’s, the 12μm devices use a “back-to-back” diode arrangement, whereby the waveband is selected by changing the bias polarity across the diode stack; thus ensuring spatial coherence between the two wavebands. The increased thickness of DWIR MCT compared to single-band material makes manufacturing the mesa structure, in order to control inter-pixel crosstalk increasingly challenging with smaller pixel pitches. Previous publications by Leonardo UK presented results of 12μm DWIR technology on a 24μm Readout Integrated Circuit (ROIC), allowing only 25% of the pixels to be assessed; in this paper, we discuss results of this material on a 12μm ROIC, enabling assessment of 100% of the pixels. Low defects together with near Background Limited Infra-red Photodetector (BLIP) performance demonstrates significant progress towards the manufacture of higher resolution, lower cost DWIR devices by Leonardo UK.
Conference Committee Involvement (4)
Infrared Technology and Applications LI
13 April 2025 | Orlando, Florida, United States
Infrared Technology and Applications L
21 April 2024 | National Harbor, Maryland, United States
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