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  • Magnetic - 2D Magnetic Device Simulator
    caused by magnetic field can be observed Magnetic field sensors can be simulated Effect of stray magnetic fields on device performance can be modeled Shows the Hall voltage generated across a simple semiconducting resistor as a function of the bias applied along the resistor The simulation includes field dependent mobility and the Hall voltage consequently varies sub linearly with applied voltage The opposite carrier types give opposite signs for the Hall voltage A simple NPN magnetotransistor structure showing net doping contours and the position of the p n junctions It is biased in a common emitter arrangement with 10 V bias applied to the collector contacts The base contacts are then biased from 0 0 V to 0 65 V Results are obtained without a magnetic field and also with a uniform magnetic field of 1 Tesla applied perpendicular to the device The electron current along the horizontal cutline at 90 microns in the magnetotransistor Without an applied magnetic field it is symmetric about the device centerline but the magnetic field gives an asymmetry which results in a current differential between collector 1 and collector 2 This is due solely to the deflection of the current flowlines by the applied magnetic field The collector currents in the magnetotransistor for an Applied field of 1 0 Tesla The difference between them allows the magnetic field to be measured Both collector currents are identical when the magnetic field is absent The current gains of the structure obtained by dividing collector 1 current by base 1 current and collector 2 current by base 2 current One is enhanced relative to the zero magnetic field case and the other is diminished Rev 110113 02 Download More About Magnetic Brochure PDF 852 Kb Presentation Materials Examples Supported Platforms X Supported Platforms 2015 Baseline Enterprise 5

    Original URL path: http://www.silvaco.fr/products/vwf/atlas/2D/magnetic2D/magnetic2D_br.html (2016-05-03)
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  • Quantum - 2D Simulation Models for Quantum Mechanical Effects
    Vg left and Id Vd right characteristics of ballistic DGT computed with NEGF approach Due to the assumption of ballistic transport the computed current gives an upper limit for the particular device Transmission coefficient left current spectrum center and density of states right in the ballistic double gate transistor a Each step of the transmission coefficient corresponds to an extra electron sub band becoming available for transport b The lowest sub band gives the highest contribution to current c Oscillatory nature of density of states in the source extension region is due to electron reflections at the injection barrier Drift Diffusion Mode Space Model The Drift Diffusion Mode Space Model DDMS is a semi classical approach to transport in devices with strong transverse confinement and is a simpler alternative to mode space NEGF approach Similarly to the mode space NEGF the solution is decoupled into 1D or cylindrical Schrodinger equation in transverse direction and 1D transport equations in each subband In this model however a classical drift diffusion equation is solved instead of a quantum transport equation Thus the model captures quantum effects in transverse direction and yet inherits all familiar ATLAS models for mobility recombination impact ionization and band to band tunneling Here we show a current flow as computed by DDMS in a double gate FET with Lg 30nm and body thickness t 2nm 1D drift diffusion equations are solved in each subband in the presence of trap recombination SRH band to band tunneling BBT and impact ionization Current density is increased in the end of the channel due to e h pair generation This figure shows electron top left and hole top right carrier densities and the lowest electron subband energy with green and without red generation recombination mechanisms The e h pair generation causes a slight increase in electron concentration top left and a tremendous increase in the concentration of holes top right which are accumulated in the channel The charge accumulation resets the threshold voltage and decreases the source injection barrier for electrons bottom Drain current drain voltage characteristics computed by DDMS show a strong floating body effect and a poor saturation right when the mechanisms of BBT and impact ionization are present as compared to the case when generation recombination is neglected left Band to Band Quantum Tunneling Models Quantum has the capability to calculate band to band tunneling in semiconductors Both the trap assisted and direct components can be calculated The direct component can be calculated by using either a local or non local model In the local model the electric field at each point is used to give a rate for the generation of electron hole pairs at that point The non local model is more sophisticated in that it calculates the tunneling current for each energy at which tunneling is possible Furthermore the sources reverse bias and sinks forward bias of carriers occur at the correctly spatially separated positions in the device An example of forward current in a tunnel diode

    Original URL path: http://www.silvaco.fr/products/vwf/atlas/2D/quantum2D/quantum2D_br.html (2016-05-03)
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  • Luminous - 2D Optoelectronics Device Simulator
    evaluation of vertical cross sections at several x axis locations is used to illustrate the peak potential across the device channel High Speed and Communication Photodectors Luminous analyzes photodetectors used in high speed and low noise applications such as communications hardware It provides a cost effective solution for optimizing device structures Impact ionization rate contours at operating bias for a Reach Through Avalanche Photodiode RAPD An important feature of this device is the n type guard ring that is used to prevent premature breakdown at the edges of the front surface n region The peak impact ionization region is in the intended multiplication region Luminous enables easy evaluations of different device structures and guard ring geometries Important device characteristics such as quantum efficiency spectral response and frequency response are easily extracted using Luminous Shown is the response to a high frequency variable light source Luminous also permits simulation of transient response Here the lag between a rapid turn off of the light and the resultant photodetected current Luminous allows the specification and simulation of multi layer anti reflective coatings Shown is a comparison of the spectral response of a device with and without anti reflective coatings as compared to the ideal response Luminous allows very general specification of the optical source In this example we show a Gaussian source intensity with non normal incidence and periodic boundaries Solar Cells Solar cell characteristics such as collection efficiency spectral response open circuit voltage and short circuit current can be extracted with Luminous By varying the incident wavelengths a spectral response can be modeled The green curve is the current from the light source and the blue curve is the actual terminal current The ray trace features in Luminous enable the analysis of advanced designs Shown above is the simulation of photogeneration rates from an angled light beam Beam Propagation Method Luminous includes physical models that take into account the wave nature of light Diffraction of light as well as coherent effects can be analyzed using beam propagation method Beam propagation method in Luminous takes into account diffraction of light Spreading of a narrow Gaussian beam due to diffraction affects the distribution of photogenerated carriers in Silicon Beam propagation method in Luminous can be used for analysis of light propagation in complex structures Light reflection and refraction on a Silicon oxide Silicon boundary is shown in this figure Interference of incident and reflected light is taken into account High Intensity Optical Beams for Rapid Thermal Annealling Applications Optical beams are used in semiconductor processing for rapid thermal anneals of whole wafers using infraread lamps or for localized re crystalization using a high intensity laser beam swept across the wafer in a raster fashion Both of these applications can be simulated directly using Luminous in conjunction with Giga to model the temperature rise from the optically stimulated electron hole pair recombination processes The examples on this page depict the transient localized temperature evolution of a high intensity laser beam being swept across the surface

    Original URL path: http://www.silvaco.fr/products/vwf/atlas/luminous/luminous_br.html (2016-05-03)
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  • LED - 2D Light Emitting Diode Simulator
    LED output coupling and directionality using reverse ray tracing The emission spectrum derived from quantum well modeling with reverse ray tracing or finite difference time domain modeling give the LED output spectrum as a function of device structure and operating conditions A typical GaAs AlGaAs LED device structure A contour plot of the on state radiative recombination rate in the LED device A contour plot of the local temperature in the LED at operating bias The calculated output spectrum of an LED device The calculated optical intensity of the LED as a function of bias voltage Peak emission wavelength of the LED as a function of input current Angular dependence of intensity for the LED as calculated using reverse ray tracing 2D Finite Difference Time Domain Anaysis of LED Output Coupling These figures illustrate how the FDTD electric fields are taken at a sequence of dipole locations in the active layer The analysis of LED coupling using FDTD begins by placing the LED device in the FDTD domain In the attached figure we show a simple device located between two PMLs Photonic coupling devices can be placed in the air above the device The results from the dipole scans are integrated weighted with the local spontaneous emission spectrum to obtain characterizations of output coupling as a function of wavelength and geometry as shown in the accompanying figure In this figure a photonic crystal regular spaced columns is placed on top of the LED FDTD analysis can be run on such a strucure to quantify the improvement in coupling of various photonic designs This sequence of figures illustrates the effect of a photonic output coupling structure in this case regular columns on electric field in spatial analysis of wavelength dependent LED output coupling LED simulation allows you to examine internal characteristics

    Original URL path: http://www.silvaco.fr/products/vwf/atlas/2D/led/led_br.html (2016-05-03)
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  • VCSEL - Vertical Cavity Surface Emitting Laser Simulations
    the left the we see the entire cross section which shows both the upper and lower DBRs and the active layers The right panel shows the enlarged cross section around the active layers where we can see that this device contains a six layer multiple quantum well Optical intensity of the principal longitudinal and transverse mode This mode is lasing at the designed wavelength Enlarged cross section around the quantum wells The figure shows the radiative recombination rate in the wells VCSEL uses accurate numerical models to predict the gain and radiative rates including the effects of quantum confinement The photon rate equation is solved self consistently with the device equations to determine the output optical intensity as a function of device bias The heat flow equation can also be solved self consistently to examine the effects of self heating In this figure we show a plot of the maximim temperature versus the device current Lattice temperature contours inside the VCSEL at lasing The temperature dependence of material parameters such as refractive index are included to examine the effects of self heating on optical behavior of the VCSEL Multiple transverse modes can also be simulated These figures show the optical

    Original URL path: http://www.silvaco.fr/products/vwf/atlas/vcsels/vcsels.html (2016-05-03)
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  • Organic Display - OLED and OTFT Organic Display Simulator
    exciton parameters Dipole emission model User definable singlet to triplet exciton generation rate Forster mechanism for dopant dipole dipole energy transfer Steady state and transient analysis State of the art reverse ray tracing model to give electro luminescence spectral emission characteristics CIE x y Chart Hopping mobility as a function of Dopant Concentration for an OTFT device OLED structure made by Atlas The band structure electron hole concentration and radiative exciton profiles for the Hole Transport Layer HTL and the Electron Transport Layer ETL regions are shown EL Spectrum The Electro Luminescent EL spectrum is calculated from the input Photo Luminescent PL spectrum and the output coupling The output coupling is calculated using the dipole radiation method and ray tracing in the multiple cavity stacks using wavelength dependent refractive indexes Emissive layer Alq3 input PL spectrum EL emission spectrum Output angular power density for the TE and TM modes Recombination zone shift and the EL spectrum emission shift due to current injection CIE x y chart showing the color points in the CIE diagram Host and Dopant Langevin Recombination Rates Rev 110113 03 Download More about Organic Display Brochure 1 6 Mb Presentation Materials Examples Supported Platforms X Supported Platforms

    Original URL path: http://www.silvaco.fr/products/vwf/atlas/organicdisplay/organicdisplay_br.html (2016-05-03)
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  • Organic Solar - Organic Solar Cell and Photodetector Simulator
    equations Exciton generation diffusion lifetime and quenching effects Doping specific exciton density calculation User definable exciton parameters such as diffusion length and lifetime User definable singlet to triplet exciton generation rate Steady state transient and AC analysis Band diagram of zero bias organic heterojunction p i i n solar cell Each region adopts various characteristics of the associated organic material including band gap charged carrier mobilities excitonic recombination and dissociation component rates absorption characteristics etc User may modify all parameter defaults to calibrate to measurement Some commonly used materials have built in default values This figure shows the densities of charged carriers and excitons In this case note that the excitons are photogenerated in the blend layer and diffuse to either side The elevated concentrations of charge carriers in the intrinsic regions are due to the generation of electron hole pairs through dissociation of excitons Here the solar cell power is shown to decrease with increased nonradiative decay rate of excitons The nonradiative decay of excitons competes with exciton dissociation in the dissipation of photogenerated excitons This figure shows the effects of singlet binding energy on the solar cell I V characteristic The binding energy is introduced though the exciton dissociation rate calculation This figure shows a schematic of the layers in a hypothetical organic color imaging cell Shown are the layers for one color Color sensitivity is defined by selection of photosensitive material In this case Cobalt TTP is selected for blue sensitivity Three color sensitive cells can be stacked to achieve three color sensitivity of a organic imaging cell as shown in this schematic Ref Seo et al Color Sensors with Three Vertically Stacked Organic Photodetectors Jpn J Appl Phys V 46 No 49 pp L1240 L1242 Rev 110113 02 Download More about Organic Solar Brochure 588Kb Presentation

    Original URL path: http://www.silvaco.fr/products/vwf/atlas/organicsolar/organicsolar_br.html (2016-05-03)
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  • Laser - Semiconductor Laser Diode Simulator
    laser diode are obtained using Atlas Blaze Optical solutions are obtained by Laser in a smaller domain around the active layer This figure shows the near field light intensity in the fundamental transverse mode Simulated laser output power as a function of anode current for the InP InGaAsP laser diode Important characteristics such as laser threshold current are readily extracted Laser gain as a function of bias The gain rises until the laser threshold After the threshold the gain remains constant and equal to the laser losses Laser was applied to the InP InGaAsP laser diode To obtain this above threshold laser spectrum multiple longitudinal modes were simulated with energies between 1 065 and 1 09 eV Comparison of the simulated gain spectra below and above lasing threshold for the InP InGaAsP laser diode Laser can also calculate the far field patterns of laser diodes The figure above shows the far field pattern of the InP InGaAsP laser diode Laser was applied to a GaAs AlGaAs laser diode shown above This device has two n AlGaAs cladding layers to confine the light profile The primary transverse mode light profile is shown GaAs Laser Diode Light intensity from strip laser showing double spot The near field pattern is distorted due to spatial hole burning in the active layer Laser response to a voltage sweep showing the threshold and subthreshold characteristics of the strip laser Laser incorporates the photon equation in its set of self consistent equations This allows transient simulations to be preformed that accurately reproduce more complex behavior This figure shows the result of a small voltage perturbation to the anode voltage The transient simulation shows the resulting oscillations which are commonly referred to as relaxation oscillations Laser can simulate multiple transverse optical modes These figures show the first four

    Original URL path: http://www.silvaco.fr/products/vwf/atlas/laser/laser_br.html (2016-05-03)
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