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• Carrier localization in the InAsSb/InSb digital alloy nBn detector varies substantially with spatial location. • This is likely caused by macro-scale nonuniformities in the growth at the mm scale. • These nonuniformities may include sub-monolayer fluctuations in layer thickness and fluctuations in alloy composition. Recently we have demonstrated a novel method of extending the cut-off wavelength of InAsSb nBn detectors, by incorporating a series of monolayers of InSb, which we have termed a digital alloy. In recent work we have shown that while increasing temperature from 15 K to 40 K we observe a 14 meV blue shift of the photoluminescence peak energy and a decrease in minority carrier lifetime. We have hypothesized this effect is due to carrier localization caused by macro-scale fluctuations in layer thickness or alloy composition. Here we study the spatial variation of this effect over the surface of a sample, demonstrating significant variation with position. We discuss implications of this for the carrier localization hypothesis. [ABSTRACT FROM AUTHOR]

Abstract This paper reports on the demonstration of two-terminal, two-color (visible/midwave-infrared, MWIR) photodetectors (2CPDs) consisting of monolithically-integrated CdTe nBn and InSb PN sub-detectors connected by an n-CdTe/p-InSb heterovalent tunnel junction grown on lattice-matched InSb substrates. The 2CPD can be switched between MWIR (1.5–5.5 μm with a peak responsivity of 0.75 A/W at 77 K) and visible (350–780 nm with a peak responsivity of 0.3 A/W) detection bands by applying different optical and electrical biases. Band rejection ratios of 18 dB and 52 dB, and spectral cross-talks of 40 dB and 31 dB are achieved for the visible and the MWIR bands, respectively. This 2CPD can be potentially used for visible/MWIR two-color focal plane arrays with optimal fill-factors and zero spatial offset between the visible and MWIR imaging channels. [ABSTRACT FROM AUTHOR]

The effect of hydrostatic compression on elastic constants and related properties in InSb have been investigated using a pseudopotential approach. At zero pressure, our results are found to compare reasonably well with experiment. A monotonous pressure dependence of all features of interest has been observed. The mechanical stability criteria has been checked in terms of elastic constants and pressure. Upon compression, InSb is found to become more resistant to the deflection or deformation. An increase of micro hardness of the material in question has been seen when pressure is applied suggesting thus that InSb under pressure is a useful material in the fabrication of devices. The behavior of the Kleinman internal parameter with pressure indicates that InSb exhibits strong resistance to changes in its bond length. [ABSTRACT FROM AUTHOR]

Highlights: [•] Mesa type InSb photodiodes were fabricated on epitaxial layer grown by MBE. [•] Thermal cleaning of InSb surface was carried out to remove the oxide of the substrate surface. [•] The parameters of photodiodes with small sensitive area are comparable to the parameters of better bulk InSb diodes. [ABSTRACT FROM AUTHOR]

Abstract: InSb is a III–V binary semiconductor material with a bandgap wavelength of 5.4μm at 77K, well matched to the 3–5μm MWIR atmospheric transmission window. When configured as a Focal Plane Array (FPA) detector, InSb photodiodes offer a large quantum efficiency, combined with excellent uniformity and high pixel operability. As such, InSb arrays exhibit good scalability and are an excellent choice for large format FPAs at a reasonable cost. The dark current is caused by Generation–Recombination (G–R) centres in the diode depletion region, and this leads to a typical operating temperature of ∼80K in detectors with a planar implanted p–n junction. Over the last 15years SCD has developed and manufactured a number of different 2-dimensional planar FPA formats, with pitches in the range of 15–30μm. In recent years a new epi-InSb technology has been developed at SCD, in which the G–R contribution to the dark current is reduced. This enables InSb detector operation at 95–100K, with equivalent performance to standard InSb at 80K. In addition, using a new patented XBn n device architecture in which the G–R current is totally suppressed, epitaxial InAsSb detectors have been developed with a bandgap wavelength of 4.2μm, which can operate in the 150–170K range. In this short review of the past two decades, a number of key achievements in SCD’s InSb based detector development program are described. These include High Operating Temperature (HOT) epi-InSb FPAs, large format megapixel FPAs with high functionality using a digital Read Out Integrated Circuit (ROIC), and ultra low Size, Weight and Power (SWaP) FPAs based on the HOT XBn n architecture. [Copyright &y& Elsevier]

Abstract: InSb has been grown by liquid phase epitaxy using indium rich solutions with a supercooling of 2–5°C onto (111) oriented Cd0.955Zn0.045Te substrates at 400–405°C. The resulting epitaxial layers were extensively characterized using X-ray diffraction, optical microscopy, Raman spectroscopy and photoluminescence. [Copyright &y& Elsevier]

Abstract: A procedure is described where the response function of each pixel of an InSb detector is determined by radiometric self-calibration. With the present approach no knowledge of the spectral characteristics of the IR system is required to recover a quantity which is linear with the incident irradiance of the object. The inherent detector non-uniformity is corrected on the basis of self-calibrated scaled irradiance. Compared to the standard two-point non-uniformity correction procedure – performed with the detector signal – only two NUC-tables are required for arbitrary integration times. Images obtained at various exposures are fused to a single high dynamic range image. The procedure is validated with synthetic data and its performance is demonstrated by measurements performed with a high resolution InSb FPA. [Copyright &y& Elsevier]

Abstract: Ar+ ion milling of InSb for manufacturing single electron devices was studied. It is shown that pyramidal structures (porous) are created on the (111) surface of InSb wafers by anisotropic etching. Also it was shown the axis of the pyramidal structure is a function of the angle of the Ar+ incident beam and does not depend on the energy of the beam. EDX measurement results show In x O y and Sb x O y were not created on the surface after milling process. FTIR measurement results show that the surface reflection was decreased and less than 0.3V flat band voltage was seen in capacitance voltage measurement results. SEM images show that the etching has approximately vertical profile. Therefore the Ar+ milling technique can be used as a dry etching technique for manufacturing mesa and/or porous structures of InSb. Since the surface is porous and of near-pyramidal morphology, one can simulate the surface by a set of needles each of which is a nanometer-size capacitance (i.e. single electron device). We showed, the threshold voltage of this single electron device is 0.3V approximately, and therefore it can be used for studying single-electron or Coulomb blockade effects. [Copyright &y& Elsevier]

Abstract: Infrared (IR) focal-plane arrays (FPA’s) with high spatial resolution play an important role in military imaging. Image degradation through blooming of the FPA by either thermal or monochromatic sources seriously limits their effectiveness. However, little has been published discerning the phenomena responsible for this blooming. We studied the blooming effects in a 640×480 indium-antimonide (InSb) FPA with 20-μm pixel-to-pixel spacing and operated at 77K. Electronic and optical blooming from both a high-intensity blackbody source and a 4.6-μm narrow-line-width laser source was studied. A 30-μm pinhole mask was fastened directly to the FPA to achieve spatial isolation of individual pixels in order to separate the optical and electronic effects. Both sources were used to bloom the FPA with and without the mask, and images were captured and analyzed. We provide conclusive evidence that optical effects of ghosting, diffraction, and lens and housing scatter dominate, resulting in global (i.e., large area of the FPA) loss of image quality, while effects due to electronic phenomena, such as carrier-diffusion, are minimal and locally confined to on-the-order-of-one pixel. A simple model of carrier transport was constructed to provide the theoretical basis for our conclusions. [Copyright &y& Elsevier]