IRnova AB

Kista, Sweden

IRnova AB

Kista, Sweden
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Asplund C.,IRnova AB | Marcks von Wurtemberg R.,IRnova AB | Hoglund L.,IRnova AB
Infrared Physics and Technology | Year: 2017

In this paper, we present a range of modeling tools that are used in the design and performance evaluation of type-II superlattice detectors. Among these is an optical and photo carrier transport model for the spectral total external QE, which takes into account carrier diffusion length. Using this model, the diffusion length is extracted from external quantum efficiency measurements. It can also be used to fine-tune an optical cavity in relation to the wavelength range of interest for optimal quantum efficiency. Furthermore, an electrical device model for band bending, dark current and doping optimization is described. The modeling tools are discussed and examples of their use are given for MWIR type-II detectors based on InAs/AlSb/GaSb superlattices. © 2017.

Lourdudoss S.,KTH Royal Institute of Technology | Junesand C.,Finisar | Kataria H.,IRNova AB | Metaferia W.,Lund University | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017

We present and compare the existing methods of heteroepitaxy of III-Vs on silicon and their trends. We focus on the epitaxial lateral overgrowth (ELOG) method as a means of achieving good quality III-Vs on silicon. Initially conducted primarily by near-equilibrium epitaxial methods such as liquid phase epitaxy and hydride vapour phase epitaxy, nowadays ELOG is being carried out even by non-equilibrium methods such as metal organic vapour phase epitaxy. In the ELOG method, the intermediate defective seed and the mask layers still exist between the laterally grown purer III-V layer and silicon. In a modified ELOG method called corrugated epitaxial lateral overgrowth (CELOG) method, it is possible to obtain direct interface between the III-V layer and silicon. In this presentation we exemplify some recent results obtained by these techniques. We assess the potentials of these methods along with the other existing methods for realizing truly monolithic photonic integration on silicon and III-V/Si heterojunction solar cells. © 2017 SPIE.

Hoglund L.,IRnova AB | Marcks Von Wurtemberg R.,IRnova AB | Asplund C.,IRnova AB | Kataria H.,IRnova AB | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017

Development towards higher operating temperature, smaller pitch and larger format arrays is ongoing for midwave (MW) InAs/GaSb superlattice detectors at IRnova. One part of this effort entails improvement in the MW detector design, which has resulted in increased quantum efficiency to 55-60 % in the entire 3-5 μm wavelength region, with dark current levels lower than 3×10-6 A/cm2 at 120 K. Furthermore, MW-MW dual band detectors have been realized by using pixel filters fabricated on top of regular MW FPAs. The pixel filters were designed to transmit infrared radiation in the 3.5 μm - 4.1 μm wavelength region and to completely block light shorter than 3.5 μm. By comparing the signals of filtered and unfiltered pixels, excellent contrast between the two bands were obtained. Long wave infrared detectors have also been realized with cut-off wavelength at 12.2 μm and dark current levels following the Rule07 trendline from 80 K to 160 K, with only two times higher dark current than Rule07 at 80 K. © 2017 SPIE.

Agency: European Commission | Branch: FP7 | Program: CP | Phase: ICT-2011.3.5 | Award Amount: 10.64M | Year: 2012

In recent years it has become clear that mid-IR imaging spectroscopy has the potential to open a new chapter in bio-medical imaging and offers an effective tool for early cancer diagnosis and improved survival rates. Rather than a search for cancer marker absorption peaks, great progress has been made by analysing the entire bio-molecular mid-IR spectral signature using automated algorithms. However, the lack of suitable sources, detectors and components has restricted the technology to one of academic interest, based on weak thermal sources, low power lasers or synchrotron research tools.For the first time the photonic technology is in place to develop a new mid-IR technology platform on which entirely novel supercontinuum sources (c. 1000x brighter than thermal sources) covering the whole range from 1.5 to 12 m may be built:-Low loss robust chalcogenide fibres for fibre lasers, supercontinuum generation and delivery -Fibre end caps, splicing and fusion technology for soft glass fibres -Crystal technology and novel designs for mid-IR AO modulators based on calomel -Flexible fast AO driver technology to enable high speed HSI acquisition -Low cost T2SL FPA detectors with performance matching state-of-the-art MSL devices -2.9 m Er:ZBLAN and 4.5 m Pr-doped chalcogenide fibre laser pumps -Robust designs for a range of mid-IR SCG sources: a) 1.5-4.5 m from ZBLAN fibre b) 1.5-5.5 m from InF3 fibre c) 3-9 m from 2.9 m pumped PCF chalcogenide fibre d) 4-12 m from 4.5 m pumped step-index chalcogenide fibre.Two specific high impact applications will be addressed: high volume pathology screening (i.e. automated microscope-based examination of samples) and in vivo, remote, real-time skin surface examination (i.e. non-invasive investigation of suspected skin cancer).This project will open the mid-IR to further exploitation, and the technology developed will be transferable to a huge range of applications both in bio-photonics and in wider industry.

Karim A.,Acreo Ab | Gustafsson O.,KTH Royal Institute of Technology | Savage S.,Acreo Ab | Wang Q.,Acreo Ab | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

We report on the device characterization of In(Ga)Sb/InAs quantum dots (QDs) based photodetectors for long wave IR detectors. The detection principle of these quantum-dot infrared photodetectors (QDIPs) is based on the spatially indirect transition between the In(Ga)Sb QDs and the InAs matrix, as a result of the type-II band alignment. Such photodetectors are expected to have lower dark currents and higher operating temperatures compared to the current state of the art InSb and mercury cadmium telluride (MCT) technology. The In(Ga)Sb QD structures were grown using metal-organic vapour-phase epitaxy and explored using structural, electrical and optical characterization techniques. Material development resulted in obtaining photoluminescence up to 10 μm, which is the longest wavelength reported in this material system. We have fabricated different photovoltaic IR detectors from the developed material that show absorption up to 8 μm. Photoresponse spectra, showing In(Ga)Sb QD related absorption edge, were obtained up to 200 K. Detectors with different In(Ga)Sb QDs showing different cut-off wavelengths were investigated for photoresponse. Photoresponse in these detectors is thermally activated with different activation energies for devices with different cut-off wavelengths. Devices with longer cut-off wavelength exhibit higher activation energies. We can interpret this using the energy band diagram of the dots/matrix system for different QD sizes. © 2013 SPIE.

Malm H.,IRnova AB | Von Wurtemberg R.M.,IRnova AB | Asplund C.,IRnova AB | Martijn H.,IRnova AB | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

A mid wave infrared type-II superlattice focal plane array with 320x256 pixels, 30 μm pitch and 90 % fill factor was fabricated in house, using a conventional homojunction p-i-n photodiode design and the ISC9705 readout circuit. High-quality imaging up to 110 K is demonstrated with the substrate fully removed. The absorber is 2 μm thick, and no anti-reflection coating was used, so there is still room for significant improvement of the quantum efficiency, which is in the 40 % range. Studies of the dark current vs. temperature behavior indicate that the device is limited by Shockley-Read-Hall generation from the depletion region. The activation energy of this dark current component is 0.13 eV, suggesting an unidentified recombination center positioned halfway into the 0.24 eV bandgap. Furthermore, we report on detectors with 100 % cut-off at 13 μm. The dark current density at 60 K and -50 mV bias is 2x10-4 A/cm2. Quantum efficiency, NETD and BLIP temperature are also calculated. Position-sensitive photocurrent measurements on mesa-etched superlattice material were made at low temperatures using a focused laser spot. The lateral diffusion length for holes was extracted and is reported. © 2012 SPIE.

Gustafsson O.,KTH Royal Institute of Technology | Karim A.,Acreo Ab | Berggren J.,KTH Royal Institute of Technology | Wang Q.,Acreo Ab | And 12 more authors.
Optics Express | Year: 2012

InSb-based quantum dots grown by metal-organic vapor-phase epitaxy (MOVPE) on InAs substrates are studied for use as the active material in interband photon detectors. Long-wavelength infrared (LWIR) photoluminescence is demonstrated with peak emission at 8.5 μm and photoresponse, interpreted to originate from type-II interband transitions in a p-i-n photodiode, was measured up to 6 μm, both at 80 K. The possibilities and benefits of operation in the LWIR range (8-12 μm) are discussed and the results suggest that InSb-based quantum dot structures can be suitable candidates for photon detection in the LWIR regime. © 2012 Optical Society of America.

Gustafsson O.,KTH Royal Institute of Technology | Karim A.,Acreo Ab | Wang Q.,Acreo Ab | Berggren J.,KTH Royal Institute of Technology | And 3 more authors.
Infrared Physics and Technology | Year: 2013

We study the growth of self-assembled InGaSb/InAs quantum dots (QDs) and investigate how gallium can be used to reduce the optical transition energy in the InSb QD system. InGaSb QDs were grown on InAs (0 0 1) substrates by metal-organic vapor-phase epitaxy (MOVPE) and the material was characterized by photoluminescence (PL) measurements. A PL peak wavelength is demonstrated beyond 8 μm at 77 K, which is significantly longer than what has been reported for InSb QDs. The results suggest that InGaSb QDs can be grown at a larger size than InSb QDs leading to reduced confinement in the QDs. © 2012 Elsevier B.V. All rights reserved.

Martijn H.,IRnova AB | Gamfeldt A.,IRnova AB | Asplund C.,IRnova AB | Smuk S.,IRnova AB | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

IRnova has a long history of producing QWIPs for the LWIR band. In this paper we give an overview of the current products (FPAs with 640x480 and 384x288 pixels respectively, and 25 μm pitch) and their performance. Their superior stability and uniformity inherent to detectors based on III/V material system will be demonstrated. Furthermore, an IDCA specifically designed for hand-held systems used for the detection of SF6 gas using a 0.5 W cooler will be presented. The detector format is 320x256 pixels with 30 μm pitch using the ISC9705 read out circuit. The peak wavelength is at 10.55 μm and the NETD is 22 mK. © 2016 SPIE.

Asplund C.,IRnova AB | Marcks Von Wurtemberg R.,IRnova AB | Lantz D.,IRnova AB | Malm H.,IRnova AB | And 4 more authors.
Infrared Physics and Technology | Year: 2013

A heterojunction T2SL barrier detector which effectively blocks majority carrier leakage over the pn-junction was designed and fabricated for the mid-wave infrared (MWIR) atmospheric transmission window. The layers in the barrier region comprised AlSb, GaSb and InAs, and the thicknesses were selected by using k · P-based energy band modeling to achieve maximum valence band offset, while maintaining close to zero conduction band discontinuity in a way similar to the work of Abdollahi Pour et al. [1] The barrier-structure has a 50% cutoff at 4.75 μm and 40% quantum efficiency and shows a dark current density of 6 × 10-6 A/cm2 at -0.05 V bias and 120 K. This is one order of magnitude lower than for comparable T2SL-structures without the barrier. Further improvement of the (non-surface related) bulk dark current can be expected with optimized doping of the absorber and barrier, and by fine tuning of the barrier layer design. We discuss the effect of barrier doping on dark current based on simulations. A T2SL focal plane array with 320 × 256 pixels, 30 μm pitch and 90% fill factor was processed in house using a conventional homojunction p-i-n photodiode architecture and the ISC9705 readout circuit. High-quality imaging up to 110 K was demonstrated with the substrate fully removed. © 2012 Elsevier B.V. All rights reserved.

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