| 1. |
- Delmas, M., et al.
(författare)
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HOT MWIR T2SL detectors to reduce system : Size, weight, and power
- 2021
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Ingår i: Sensors, Systems, and Next-Generation Satellites XXV. - : SPIE - International Society for Optical Engineering.
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Konferensbidrag (refereegranskat)abstract
- In 2019, IRnova launched a full-scale production of a reduced size, weight and power integrated detector dewar cooler assemblies (Oden MW; VGA format with 15 μm pixel pitch) covering the full mid-wavelength infrared spectral domain (3.7 μm - 5.1 μm). Oden MW exhibits excellent performance with operating temperatures up to 110 K at F/5.5 with typical values of temporal and spatial noise equivalent temperature of 22 mK and 7 mK, respectively, and an operability higher than 99.85%. More recently, IRnova developed a new detector design with a cut-off wavelength of 5.3 μm which can potentially allow an operating temperature of the detector up to 150K with excellent performance demonstrated on single pixels with a quantum efficiency as high as 46% at 4 μm without antireflection coating, a turn on bias lower than -100 mV and a dark current density as low as 8 × 10-6 A/cm2, which is a factor of < 5 higher than Rule07. The dark current was also found independent of the device size ranging from 10 μm to 223 μm indicating that surface leakage currents are not limiting the dark current. The achievable operating temperature of an FPA made of this new detector design has been estimated to be <150 K with F/5.5 optics. These outstanding results demonstrate that this new generation of detector design is an excellent candidate for future high operating temperature and high-definition focal plane array.
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| 2. |
- Ramos Santesmases, David, et al.
(författare)
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Optical concentration in fully delineated mid-wave infrared T2SL detectors arrays
- 2023
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 123:18
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Tidskriftsartikel (refereegranskat)abstract
- The dependence of quantum efficiency (QE) on fill factor and pixel pitch is studied theoretically and experimentally in fully delineated type-II superlattice (T2SL) detectors. Theoretically, a 2-dimensional simulation model is used to compute the absorption in the array geometry, which shows an insensitivity of the optical response to the fill factor. This is a result of the photodiode array (PDA) geometry concentrating the light in the pixel area. QE measurements on PDAs with varying pixel pitch (from 225 to 10 μm) and fill factors (from 98% to 64%) confirm this independence of the QE on the fill factor and results in a 50% increase in the photocurrent density in 10 μm pitch PDAs compared to 225 μm pitch PDAs. Furthermore, measurements of the dark current density vs pixel size revealed an absence of surface leakage in these PDAs, which, combined with the increased photocurrent density results in an improved signal-to-noise ratio when reducing the pitch in these T2SL detectors. Finally, this result resolves the QE-modulation transfer function trade-off, as the electrical isolation of the pixel is carried out without impacting the QE of the array.
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| 3. |
- Ramos Santesmases, David, et al.
(författare)
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Simulation and Characterization of the Modulation Transfer Function in Fully Delineated Type-II Superlattices Infrared Detectors
- 2024
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Ingår i: IEEE Transactions on Electron Devices. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9383 .- 1557-9646. ; 71:4, s. 2459-2464
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Tidskriftsartikel (refereegranskat)abstract
- The modulation transfer function (MTF) in fully delineated 15 μ m pitch type-II superlattice (T2SL) mid-wave infrared (IR) detectors is studied theoretically and experimentally. Theoretically, a 2-D model to simulate the spot scan (SS) profile is presented and used to compute the MTF as a function of the wavelength and the array geometry (pitch size, trench width). The dependence of the detector trench on the MTF is also evaluated experimentally by the edge spread function (ESF) method according to the ISO12233 standard. The experimental results show an excellent agreement with the theoretical model, reporting an MTF of 0.61 and 0.60 at the Nyquist frequency for 1 and 2 μ m trench, respectively. With the simulation model, the effect of the increased optical crosstalk for smaller pixel pitch is discussed as a function of the trench width (0.5, 1, and 2 μ m) and incidence angle up to ± 30 ∘ . Simulation results show MTF values at the Nyquist frequency between 0.61–0.62, 0.58–0.60, and 0.55–0.57 with an average degradation of 1%, 2%, and 7% at an angle of ± 30 ∘ compared to normal incidence for the 10, 7.5, and 5 μ m pitch, respectively.
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| 4. |
- Bečanović, K, et al.
(författare)
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Age-related mitochondrial alterations in brain and skeletal muscle of the YAC128 model of Huntington disease
- 2021
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Ingår i: NPJ aging and mechanisms of disease. - : Springer Science and Business Media LLC. - 2056-3973. ; 7:1, s. 26-
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Tidskriftsartikel (refereegranskat)abstract
- Mitochondrial dysfunction and bioenergetics failure are common pathological hallmarks in Huntington’s disease (HD) and aging. In the present study, we used the YAC128 murine model of HD to examine the effects of mutant huntingtin on mitochondrial parameters related to aging in brain and skeletal muscle. We have conducted a cross-sectional natural history study of mitochondrial DNA changes in the YAC128 mouse. Here, we first show that the mitochondrial volume fraction appears to increase in the axons and dendrite regions adjacent to the striatal neuron cell bodies in old mice. Mitochondrial DNA copy number (mtDNAcn) was used as a proxy measure for mitochondrial biogenesis and function. We observed that the mtDNAcn changes significantly with age and genotype in a tissue-specific manner. We found a positive correlation between aging and the mtDNAcn in striatum and skeletal muscle but not in cortex. Notably, the YAC128 mice had lower mtDNAcn in cortex and skeletal muscle. We further show that mtDNA deletions are present in striatal and skeletal muscle tissue in both young and aged YAC128 and WT mice. Tracking gene expression levels cross-sectionally in mice allowed us to identify contributions of age and genotype to transcriptional variance in mitochondria-related genes. These findings provide insights into the role of mitochondrial dynamics in HD pathogenesis in both brain and skeletal muscle, and suggest that mtDNAcn in skeletal muscle tissue may be a potential biomarker that should be investigated further in human HD.
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| 5. |
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| 6. |
- Ramos Santesmases, David, et al.
(författare)
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Quasi-3-dimensional simulations and experimental validation of surface leakage currents in high operating temperature type-II superlattice infrared detectors
- 2022
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 132:20, s. 204501-
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Tidskriftsartikel (refereegranskat)abstract
- The surface leakage in InAs/GaSb type-II superlattice (T2SL) is studied experimentally and theoretically for photodiodes with small sizes down to 10 x 10 mu m(2). The dependence of dark current density on mesa size is studied at 110 and 200 K, and surface leakage is shown to impact both generation-recombination (GR) and diffusion dark current mechanisms. A quasi-3-dimensional model to simulate the fabrication process using surface traps on the pixel's sidewall is presented and is used to accurately represent the dark current of large and small pixels with surface leakage in the different temperature regimes. The simulations confirmed that the surface leakage current has a GR and diffusion component at low and high temperature, respectively. Finally, the surface leakage current has been correlated with the change in minority carrier concentration at the surface due to the presence of donor traps.
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| 7. |
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| 8. |
- Becanovic, Vlatko, et al.
(författare)
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HUGIN: a small satellite trying to be intelligent
- 1999
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Ingår i: Proc. SPIE. ; 3728, s. 98-
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Konferensbidrag (refereegranskat)abstract
- Micro and nano-satellites are important tools to explore and test new ideas and various new devices for space missions without spending extreme amounts of money. The actual launch cost per kilogram payload on a micro or nano-satellite can be as high or even higher than ordinary satellites but the turn around time and quick responses are extremely important. The HUGIN project is a nano-satellite (less than 10 kg) explicitly designed to test magnetic coils and adaptive artificial neural network (ANN) algorithms for attitude control purposes. A small PC video camera is also included and if the control function is successful then also tests of adaptive image processing using other ANN and biologically inspired methods will be performed.
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| 9. |
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