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Transcript of Integrated Systems Engineering - · PDF fileIntegrated Systems Engineering Development, ......
Integrated Systems EngineeringDevelopment, Modeling, and Optimization of MicroelectronicProcesses, Devices, Circuits, and Systems
August 2004 for NUSOD 2004
Dessis for Optoelectronics
Speaker: Wei-Choon Ng
Email: [email protected]
ISE Inc., San Jose, California.
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• Introduction
• Components of a Laser/LED Simulator
• Highlights of Some Advanced Physics
• Optoelectronics Examples
Overview
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Introduction to OptoelectronicsIntroduction to Optoelectronics
Simulation in Simulation in DessisDessis
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History
• History of electronic simulator– 1993, spinoff from research of Swiss Federal
Institute of Technology, ETH, Zurich– Became industry standard for modeling CMOS
devices, HEMTs, HBTs and high power devices• History of laser simulator
– 1999, added optics, QW, gain and photon rate modules to the electronic simulator
– 2000, VCSEL simulation enabled– 2002, better gain modeling– 2002, photodetector modules added
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History and Future
• History of laser/LED simulator– 2003, ray tracing module enabling LED
simulation– 2004, Full 3D edge emitter simulation– 2004, Noise and AC models for lasers
• The future…research at ETH– Superluminescent LED– Tunable lasers
• The researchers:Bernd Witzigmann, Andreas Witzig, Matthias Streiff, Michael Pfeiffer, Lutz Schneider, Stefan Odermatt, Valerio Laino, Prof. Wolfgang Fichtner
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Physics-based Optoelectronics TCAD
OpticsElectronics
Poisson ϕ,ϕ,ϕ,ϕ,n,p,TL
Continuity ϕ,ϕ,ϕ,ϕ,n,p, TL,G,A
Temperatureϕ,ϕ,ϕ,ϕ,n,p,TL
Heterostructureϕ,ϕ,ϕ,ϕ,n,p,TL,E(k),ψψψψ
MaxwellΑ,Α,Α,Α,n,p,G,νννν
Photon RateS,G,νννν,n,p
Gain ModelG,n,p,TL,νννν
Self-consistent solutions
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Time Scale
Dipole relaxation
Intraband carrierrelaxation
Optical period
Carrier scattering
10-15 10-14 10-910-1010-1110-1210-13 sec
QW carrier capture
Photon lifetimeQW radiative
recombination time
Carrier lifetime
Quantum mechanical treatment of carriers and classical treatment of optics is appled
transportcapture
intraband
escape
recombination
dipole relaxation
optical period
photon lifetime
Mirror
Mirror
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Coupling between Electronics & Optics
Electrical Problem
Poisson equation
Carrier continuity equations
Temperature/Hydrodynamic equations
QW scattering equations
Optical Problem
Helmholtz equation
Gain Calculations
Schrödinger equation
Photon rate equation
Refractive index, absorptionWavelength
Mode, photon lifetime
Material gain
Active region carrier densities
Stimulated and spontaneous emissions
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Optoelectronics Applications
• Benchmark Applications– 2D Edge Emitting Lasers (bulk, QW, Fabry-
Perot, simple DFB)– 3D Edge Emitting Lasers (with varied grating and
sectional design)– VCSELs (including gain guiding and thermal
lensing effects)– Light Emitting Diodes (LED), 2D & 3D– Photo detectors (PD, APD, MSM)– Imaging, CMOS Sensors, CCD, Solar cells
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Components of a Components of a Laser/LED SimulatorLaser/LED Simulator
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• Representation and Material Database
• Electronic Solver
• Optical Solver
• Quantum Well Transport
• Gain Calculations
• Coupling Everything
Components of a Laser Simulator
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Representation of the Problem
• Devise, new and versatile
editor that enables user to
draw 2D and 3D geometries
and intersections easily.
• Finite Box Integration
method applied to every
node of the mesh.
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Material Database
• All III-V compounds used in lasers and LEDs
• Binary, ternary, quadtenary compounds with default set
of parameters
• Users can change any parameter and define the
properties of a new material
• A PMI (Physical Model Interface) allows the user to
implement functions for certain parameters, e.g.
refractive index, bandgap narrowing, etc.
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Electronic Solver
• Poisson, Continuity, Thermodynamic and Hydrodynamic equations
• Different mobility models
• Ionization, quantization, traps, tunneling models
• Different recombination-generation models
• Degradation, radiation models
• Noise and fluctuation analysis
• Monte Carlo used to tune strained CMOS parameters
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Waveguide problem : Helmholtz equationCavity problem : Wave equation
Optical Solvers - Laser
• Finite element method (FEM)(both waveguide & cavity problems, scalar &vectorial)
• Perfectly Matched Layer (PML)(to simulate radiative boundary conditions)
• Standalone Optical Solver(to optimize mode shape and wavelength)
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Optical Solvers - PML
PML layers
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Optical Solvers - PML
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Optical Solvers - LED
LED problem : Wave equation
• Ray Tracing method(for large structures in the millimeter range)
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• Capture into QW based on a scattering process
• Separate continuum and bound states carrier continuity equations
• Drift-diffusion transport in the lateral plane of the QW
• Only bound state carriers contribute to the gain calculations
Quantum Well Transport
QW Bound States
QW Continuum States
TE
TE
SC
TE: Thermionic Emission
SC: Carrier Scattering
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• Simple model using rectangular wells
(polarization dependent optical matrix element)
• Advanced model with k.p method (Schrödinger
coupled with Poisson)
(zinc blende: 4x4, 6x6 or 8x8. wurtzite: 6x6)
• Bandgap renormalization
• Strain
• Gain broadening models
(Lorentzian, Landsberg, Hyperbolic-cosine)
Gain Calculations
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Gain Calculations
• Gain shift due to many-
body effects
(free carrier theory,
screened Hartree-Fock,
2nd Born approximation)
• Piezoelectric charge for
GaN type QWs
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• 1D gain modeling
(for initial design and fast tuning)
• PMI for loading in external table of gain values
(possibly from direct measurements)
• Option to output gain tables
(for calibration of gain parameters)
• Output k.p bandstructures and wavefunctions
Gain Calculations
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Coupling Everything
System of nonlinear equations
Mesh of Device 1
Circuit Level
System of nonlinear equations
Mesh of Device 2
Circuit Element
• Mixed-mode Simulation(combining device simulations with circuit elements self-consistently)
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• Multiple levels and dimensions
(unlimited connectivity)
• Flexible mathematical framework
(add new models easily)
• Solved by Newton and Gummel iterations
• A wide choice of sparse linear and direct solvers
• Enhanced convergence
• Steady state, Transient and AC simulations
Coupling Everything
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Highlights of Some Highlights of Some Advanced PhysicsAdvanced Physics
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Piezoelectric Field and Screening
• Quantum-confined Stark effect– Piezoelectric charge at
material interfaces � tilted quantum-well
– Quantum-well carriers are spatially distributed according to Schrödinger’s equation � separation of Electrons and Holes
– High Quantum-well carrier densities � screening of Piezoelectric charges
• Effect on laser gain– Gain reduction due to
decreased electron-hole overlap � threshold shift
Band diagram and wave functions for bound carriers. Black: no Piezoelectric charge. Red and blue: positive and negative Piezoelectric charge, respectively.
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Optoelectronic Optoelectronic
ExamplesExamples
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AlGaAs/GaAsAlGaAs/GaAs MQW MQW etched mesa VCSELetched mesa VCSEL
simulationsimulation
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Optoelectronics: VCSEL Simulation
• Simulation of Vertical-Cavity Surface-Emitting Laser (VCSEL)
• Finite-Element TypeFull-Vectorial Optical Mode Solver
• Rigorous Simulation of Diffraction Loss and Radiating Waves
• Simulation includes Spatial Hole Burning and Thermal Lensing
Oxide ConfinementBragg Mirrors
Active Region
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VCSEL: Comparison to Measurements
Output Characteristics Wavelength Tuning (includes self-heating and thermal lensing)
Reference: M. Streiff, A. Witzig, M. Pfeiffer, P. Royo, W. Fichtner: “A Comprehensive VCSEL Device Simulator”, IEEE Journal of Selected Topics in Quantum Electronics, vol. 9, no. 3, May/June 2003
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AlGaAs/GaAs MQW VCSELrotational symmetry
top AlGaAs Bragg Mirror (23 pairs)
active part
bottom AlGaAs Bragg Mirror (35 pairs)
GaAs substrate
cathode
anode anode
dielectric aperture
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AlGaAs/GaAs MQW VCSEL
Optical field distribution (HE11 mode) inside VCSEL structures for different structure geometries
Rout=10um, Rin=5um, Rconf=5um
Rout=10um, Rin=5um, Rconf=2.5um
Rout=5um, Rin=2.5um, Rconf=1.5um
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a)
c)
b)
d)
AlGaAs/GaAs MQW VCSEL
Lattice temperature distribution inside VCSEL taken at Va=1.3 V (a), 1.8V (b), 1.9V (c), and 2V (d) bias points
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VCSEL Near-Field Patterns
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Aperture (µm)
2
3
4
5
VCSELs
Typical VCSEL simulation task: Aperture optimization
Device optimization for:• Mode discrimination
• High Output power
• Good Fiber coupling
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LED SimulationLED Simulation
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Light Emitting Diodes (LEDs)
n-doped
p-doped
i-doped
anode
cathode
Optical intensity distribution inside GaN LED at 2 Volts forward bias condition
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2D MQW AlGaAs/InGaAs LED
Ray Trace portraitOptical intensity
Emission power angular distribution
Spontaneous emission in quantum wells or bulk regions is considered as radiation source
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3D MQW AlGaAs/InGaAs LED
Ray Trace portrait:- 289 active vertices
- 68 rays per active vertex
Optical intensity
“Far-field” is represented as output intensity projected to the sphere
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AlGaInPAlGaInP MQW edgeMQW edge--emitting laser on emitting laser on GaAs substrateGaAs substrate
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AlGaInP MQW laser (1)
Device structureDevice structure
active region (2 QW)
GaAs-cap
GaAs-substrate
Mesa
Current blocking layer
cathode
anode
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AlGaInP MQW laser (2)
Perfectly Match Layer (PML) approach has been used to apply the absorption boundary condition at the external boundaries
Real part of the complex optical mode intensity obtained by vectorial optical mode solver Lumi. Mode polarization is indicated by vector
Radiation waves towards the higher refractive index GaAs layers are clearly seen
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AlGaInP MQW laser (3)
Current confinement above the lasing threshold
Laser output power transient response on a current pulse
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3D Edge Emitting Laser 3D Edge Emitting Laser SimulationSimulation
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Optoelectronics: Advanced / Future Features
State-of-the-Art Active Region Models:
• k·p Bandstructure
• Manybody Gain
Full 3D Edge-Emitter Laser SimulationExample: Ridge Waveguide Multi-Section
Sampled-Grating DFB
Longitudinal Axis
Laser Beam
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CMOS SensorCMOS Sensor
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Transient Electric Field
Electric field plotted on DESSIS grid Electric field plotted on EMLAB grid
The fields are simulated in 3D, but only a cross-section is displayed here.
Steady stateMovie
P = 10 W/m2
λ = 500nm
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Power Density and Optical Generation (Movies)
P = 10 W/m2
λ = 600nm
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Charged Coupled DeviceCharged Coupled Device
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Charge Coupled Device (CCD)
CCD cell geometry Doping Profile
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CCD - Simulation Results (EMLAB)
Instantanous Poynting Field Carrier Generation Rate
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CCD –Ray Tracing vs EMLAB
Carrier Generation Rate for λλλλ=0.5 µµµµmRay Tracing EMLAB
Both generators predict the similar carrier generation patterns within the certain wavelength range
Switzerland
ISE Integrated SystemsEngineering AGBalgriststrasse 102CH-8008 ZürichSwitzerland
Phone: +41 1 389 9700Fax: +41 1 389 9797Email: [email protected]
USA
Integrated SystemsEngineering, Inc.111 North Market Street, Suite 710San Jose, CA 95113USA
Phone: +1 408 918 6300Fax: +1 408 918 6306Email: [email protected]
Japan
ISE Integrated SystemsEngineering Japan Ltd5-1, Marunouchi 1-ChomeChiyoda-kuTokyo 100-0005, Japan
Phone: +81 3 5220 3543Fax: +81 3 3282 7623Email: [email protected]
Taiwan
ISE Integrated SystemsEngineering AG, Taiwan Branch2nd Floor, No. 15, Lane 6Jinshan 6th StreetHsinchu 300, Taiwan
Phone: +886 3 567 0500Fax: +886 3 579 0546Email: [email protected]
© 2004 ISE Integrated Systems Engineering AG. All rights reserved.
Integrated Systems EngineeringDevelopment, Modeling, and Optimization of MicroelectronicProcesses, Devices, Circuits, and Systems
China
Integrated Systems Engineering(Shanghai) Co., Ltd.Room 1430, No. 498 Guoshoujing Road Pudong New DistrictShanghai 201203, China
Phone: +86 21 5080 8618Fax: +86 21 5080 7760Email: [email protected]
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Phone: +65 6744 9789Fax: +65 6741 3543Email: [email protected]
Korea
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Phone: +82 2 525 9117Fax: +82 2 525 0931Email: [email protected]
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