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TCAD in Optoelectronics Wolfgang Fichtner with a lot of help from Bernd Witzigmann Wei-Choon Ng Stefan Odermatt Mathieu

TCAD in Optoelectronics Wolfgang Fichtner with a lot of help from Bernd Witzigmann Wei-Choon Ng Stefan Odermatt Mathieu Luisier. Urbana, May 2006. Numerical laser simulation MINILASE and sons Status of TCAD Optoelectronics Latest Developments. First-principles Laser Simulation.

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TCAD in Optoelectronics Wolfgang Fichtner with a lot of help from Bernd Witzigmann Wei-Choon Ng Stefan Odermatt Mathieu

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  1. TCAD in OptoelectronicsWolfgang Fichtnerwith a lot of help fromBernd WitzigmannWei-Choon NgStefan OdermattMathieu Luisier Urbana, May 2006

  2. Numerical laser simulation MINILASE and sons Status of TCAD Optoelectronics Latest Developments First-principles Laser Simulation

  3. Karl’s Vision Classical Semiconductor Transport Simulation Self-consistency Custom Optical Solution Wave Propagation Foundation for modern laser simulators! Foundations of Laser Simulation Heterojunction transport Drift-diffusion transport Quantum well transport +

  4. Initiated by Karl with Office of Naval Research support First full 2D laser simulator MINILASE I by G.H. Song and K. Hess (1990) 2D Edge emitting laser with heterojunction transport MINILASE II by M. Grupen and K. Hess (1994) Energy transport model for QWs First MINILASE descendants at Bell Labs and ETH MINILASE III by F. Oyafuso, B.D. Klein, Y. Liu, W.C. Ng and K. Hess (2000-2002) ISE commercialized DESSIS-opto (1-3D) in 1999 Crosslight releases laser codes Synopsys releases Sentaurus-Opto in 2005 History of MINILASE and Sons

  5. Simulation Flow

  6. 1D: Band structure engineering Longitudinal optical problems 2D: Transverse mode, current confinement Temperature effects (e.g. optical far field) Thorough calibration 3D: Resolve uncertainties Longitudinal current & temp. effects Final calibration Multidimensional Approach new in 2006.06

  7. 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 TE TE Can we treat MQWs as a series of individual QWs? A rigorous NEGF analysis shows that for most typical cases, this assumption holds! QW Continuum States SC QW Bound States TE: Thermionic Emission SC: Carrier Scattering Quantum Well Transport

  8. QW Gain Calculations • Simple model using rectangular QW • Advanced model with k.p method • Efficient Schrödinger-Poisson coupling • Zincblende: 4x4, 6x6, 8x8; Wurtzite: 6x6 • Various gain broadening models • Gain shift due to many-body effects • Free carrier theory • Screened Hartree-Fock • 2nd Born approximation • Piezoelectric charge for III-N QWs

  9. Microscopic Gain Calculation: Model 980 nm InGaAs-AlGaAs Edge Emitting Laser: Hakki-Paoli vs Calculation • 8-band k•p method • Polarization dephazing rates calculated in the second Born approximation • Fermi-distributed electrons and holes in QWs • Coulomb-induced inter-subband coupling • QW size variation and mole fraction change modeled via inhomogeneous broadening

  10. Example: AlGaAs/GaAs MQW VCSEL Active Region Bragg Mirrors • Finite-Element Full-Vectorial Optical Mode Solver • Rigorous Simulation of Diffraction Loss and Radiating Waves • Simulation includes Spatial Hole Burning and Thermal Lensing • AC response (S21) • Relative intensity noise (RIN) • Frequency noise (Linewidth), Chirp Oxide Confinement

  11. AlGaAs/GaAs MQW VCSEL rotational symmetry anode anode top AlGaAs Bragg Mirror (23 pairs) dielectric aperture active part bottom AlGaAs Bragg Mirror (35 pairs) GaAs substrate cathode

  12. Dual Grid Approach “Optical” mesh “Electrical” mesh high y-resolution is required for optical field ~100k nodes high resolution at oxide edge and QW region

  13. Synopsys Sentaurus Device o measurement - simulation • Physical Models • Many-Body Gain • Multi-Mode Vectorial Optics • Continuity Eqns for e,h,T • Computational Expense • 1-D (seconds to minutes) • 2-D (minutes to hours) • 3-D (hours to days)

  14. Static CharacteristicsMulti-Mode AlGaAs VCSEL Reasonable Agreement between Simulation and Measurement

  15. Synopsys Sentaurus Device o measurement - simulation • AC/Noise Characteristics • S21, Frequency Chirp • RIN, Frequency Noise, Linewidth • Static Characteristics • L-I-V • Wavelength-Current

  16. Dynamic CharacteristicsMulti-Mode AlGaAs VCSEL Current  → Res.Freq  solid: simulation symbols: measurement No additional calibration parameters! measurement

  17. Complete Simulation Flow Optics Electro-Thermal (Noise-free) Correlation Functions

  18. Rm Rox Single-Mode OptimizationTCAD Design Variation • Specifications at T = 300 K • Single Mode Power > 1.2 mW • Resistance at 12 mA < 50 Ω • Temperature increase at 12 mA < 50 K Process Fluctuations • Oxidation: σ-Rox = 0.2 μm • Metallization: σ-Rm = 0.2 μm • Invest more money to better control • Oxidationor • Metallizationfor Yield improvement?

  19. Manufacturing WindowTCAD Design Variation: PCM Studio Interpretation: Rox↓ → P_SM  , but Rox↓ → ΔT  , R Rm ↓ → P_SM  , but Rm ↓ → Ith  , Slope↓ Nominal Design: Manufacturing Window Rox = 3.2 μm Rm = 2.9 μm Process Fluctuations?

  20. Thank You Karl!

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