IR Detectors from Vigo System - Boston Electronics Corporation

About VIGO System S.A.VIGO System S.A. is a leading innovator and manufacturer ofuncooled infraredphotodetectors. The companyhas been established tocontinue development andcommercialization of uncooledmiddle and long wavelength IRdetectors initiated by itsfounders in late 60's at MilitaryUniversity of Technology(Warsaw).Our mission is sensitive, fastconvenient and affordabledetection of IR radiation.The devices we develop arebased on unique concept of IRdetector as device thatintegrates optical, detection andelectronic functions in one monolithic chip device, made ofband-gap engineered structures.At present we manufacture photodetectors optimized for anywavelength within the 2-16 um spectral range. The devices arecharacterized by performance close to the fundamental limitsand sub nanosecond time constants.VIGO System S.A. offers products ranging from a singleelement photodetectors to integrated detection modulescontaining optics, IR detector, coolers, preamplifiers, A/Dconverters and other electronics. We provide also advancedcustom engineering services.The devices have found numerous industrial, scientific,medical, military and other applications.VIGO System is located in the high-tech industrial park atOżarów Mazowiecki, western outskirt of Warsaw, Poland. Thecompany owns two buildings with combined 1400 sq. metersof production and office space.VIGO System S.A. is ISO 9001 certified.A.P. 25.09.2010Glossary of TermsInfrared Detectors from VIGO System S.A.Hg 1-xCd xTeKnown also as Mercury Cadmium Telluride (MCT), CdHgTe,(Cd,Hg)Te or Mercadtel. Alloy of CdTe and HgTe. Change ofthe CdTe to HgTe ratio (composition or x-value) can be usedto tune optical absorption cut-off wavelength in the wide rangefrom UV to deep IR. Cooling shifts the cut-off wavelengthtowards long wavelengths. Detectors from Vigo are based oncomplex graded gap MCT structures optimized for MWIR(3-5 µm) and LWIR (8-14 µm) ranges.Current and Voltage Responsivity: R i, R vcurrent signal d R i=incident power d (in A/W)voltage signald R v=incident power d (in V/W)Current responsivity is typically used for photovoltaicdetectors and voltage responsivity for photoconductors andphotoelectromagnetic detectors.Responsivity - Width ProductThe responsivity of PC and PVM detectors decreases linearlywith increase of the device width (contact width). Thereforethe normalized (area independent) responsivity can beexpressed as the responsivity - width product.Dark Current: I darkIn PV: the current through a photovoltaic cell when the reversebias is applied to its terminals under dark conditions. The darkcurrent is the mainsource of the noisecurrent thatdetermines theminimal detectablesignal.In PC: the currentthrough a biasedphotoconductorwithout the incidentradiant power.Detector FormatsSquare and rectangular formats are used for PC, PEM and PVdevices. Round shapes are also used for some PV devices.Custom shapes are available on request.Maximum Bias Current: I maxThe maximum current that can flow through aphotoconductive or photovoltaic detector without a risk of itsdamage.Multiple Junctions Photovoltaic Devices (PVM)PVM devices are the photovoltaic devices with multiplejunctions connected in series. They are used as large area, longwavelength detectors.Noise: NThe main types of noise are:- Generation-Recombination Noise- Johnson Noise (or Thermal Noise)- Shot Noise- Flicker or 1/f NoiseG-R Noise: Both generation and recombination occurrandomly, resulting in fluctuations in the input current.Johnson Noise or Thermal Noise is caused by thermalagitation of carriers in the conductor. In consequence there israndom fluctuations in the voltage across its terminals.