What's new in LASTIP/PICS3D Version 2006.11 (Oct.29,06)

We are pleased to announce the Nov. 2006 release of LASTIP (laser technology integrated program) and PICS3D (photonic integrated circuit simulator in 3D) with the following release notes.

New or improved physical models

• Multiple-cavity laser model implemented enabling a new class of application including bipolar cascade laser and laser arrays.

• More accurate method of modal gain evaluation (based on imaginary propagation constant) available. 

• External external cavity VCSEL and large signal transient simulation for multiple segment DBR+EAM demonstrated.

• Multiple shallow dopant types may be used together.

• QWIP/QCL model improved using non-localized intersubband absorption and with non-local quantum transport effects.

• Quantum dot (QD) model can describe separate non-radiative lifetimes for QW and QD regions.

Enhanced performance

• General speed up due to improved program structure.

• Efficiency of parallel solver increased.

• Self-consistent MQW model faster with more user control.

• Speed of eigen value solver improved.

• Convergence of pics3d may be improved with new analytical optical gain model.

More convenient features

• Material macro data base system improved so that "if-else-" logical expression can be inserted anywhere within a macro function 
  just like in any high level programming language.

• Output data file identification and display are more flexibility and convenient.

• More user-control for Newton solver.

• Contact statement improved so that it is more convenient when one electrode is in contact with more than one type of semiconductor.

• Bias may be automatically terminated by current or laser power.

• Labels and tags more extensively used so that geometry location may be referenced by label name.

• High frequency AC analysis data export in Touchstone 2-port data format enabled.

• More flexible ways to define a tunneling junction.

 

Announcing APSYS Version 2006.7 (Jun.29,06)

We are pleased to announce the release of version 2006.7 of APSYS (advanced physical models for semiconductor devices).
Numerical stability and accuracy of the simulation engine of this version have been significantly improved for the treatment of strained valence bands of GaN and related group III nitrides (i.e., HH/LH/CH bands of wurtzite crystal structure). The new version comes with updated material parameters for all group III nitrides so that more reliable results may be obtained without the need for modification of default parameters. The following are more specific improvements and enhancements of the simulation engine.

• In an effort to upgrade the simulation capability of APSYS for more complex structures containing hundreds or thousands of material layers (such as quantum cascade laser and novel LED structure with super-lattices), the complex-MQW option has been enhanced to handle a new material macro type called super-structure macro which is used to include sub-projects of micro-scale simulation (say several periods within a super-lattice) so that all properties (such as density of states and effective mobility) of the sub-projects are transferred to and combined with the macro-scale device simulation.

• The multiple layer optical module has been enhanced to include resonant optical cavity calculation so that resonant cavity light emitting diode (RCLED) can be rigorously treated. Based on Green's function method, resonant effects in wavelength, angle of emission and standing wave have been included self-consistently with photon-recycling model. More details may be found in our presentation on RCLED.

• Photon-recycling model has been included in the fast-analytical LED model so that this efficient technique may be more accurate when the LED power is high. From now on all of our LED models (Fast-analytical, ray-tracing and RCLED) are capable of treating photon-recycling effects.

• Hot carrier energy dependent impact ionization has been enabled in the hydrodynamic solver so that  spatial effect of the dark space (low energy region without impact ionization) in an avalanche photodiode (APD) can be accurately taken into account. More details may be found in our presentation on APD.

• The intersubband option has been enhanced and for the first time we have demonstrated the simulation of quantum well infrared photodetector (QWIP) using a quantum corrected drift-diffusion model. More details may be found in the presentation on QWIP.

• Organic semiconductor data base is much enhanced and the organic light emitting diode (OLED) option may now be combined with the resonant cavity option to provide more realistic modeling of an OLED. Some details are available from this presentation on OLED.

• Raytracing-3D option has been enhanced so that rounded/curved surfaces may be handled without slowing down the simulation. Also more new emission source models are implemented for LED application.

• The mesh generator has been upgraded so that triangles generated for complicated 2/3D structures are now more reasonable.

• Multi-CPU/parallel option has been improved so that more parts of the code are paralleled and the overall parallel efficiency
  is increased. In previous versions parallelization were limited to the linear solver only.
  

This version also includes substantial improvement in the graphic user interface (GUI).  Here are some specifics: SimuCenter: handling of multiple file execution and improvement in simulation series stepping.  LayerBuilder/GeoEditor: better visual effects and ability
to handle more complex 3D structures such as VCSEL/RCLED.  CrosslightView: better visual effects and 3D vector/flow plots have been included.

Finally we are pleased to introduce a new GUI program series called Crosslight Design Studio which aims at completely hiding any text operations so that all simulation actions are completed via clicking on a set of predefined buttons. The first of this series is the LED Design Studio working with the new APSYS 2006.7.

 

Training Workshop on July 14 at InterOpto'06 (Jun23,06)

Crosslight Software intends to hold a free training workshop on July 14th, at InterOpto'06 (International Optoelectronics Exhibition) located at Makuhari Messe, Japan. Advanced problem solving as well as introductory hands-on training will be covered. Language of the workshop is in both Japanese and English. Admission and software training license are both free but advanced reservation is highly recommended. For more details, please contact Crosslight's Japan office at www.crosslight.jp.

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Crosslight Workshop on Sept. 15 at NUSOD06 (Jun13,06)

Crosslight invites everyone to a free training workshop on 15 Sept. 2006 in Nanyang Technology University, Singapore, to be held after the NUSOD06 conference. Dr. Joachim Piprek, an international expert in using Crosslight's device simulators, has been invited to lecture
on how to create realistic device simulations at this hands-on tutorial workshop. All registered participants are eligible to receive a free training license of Crosslight's simulation software. For more details, please visit the conference website. 

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Recent Simulation Software Updates (May30,06)

We wish to update our users on the following recent simulator improvements. In addition to numerous minor modifications, the device simulators (APSYS/PICS3D/LASTIP) version 2005.11/may06-patch improves on both speed and accuracy mainly affecting the thermal option. CSUPREM (2/3D) has fixed a mesh related bug contained in the original code from Stanford University.  Also the lower limit of the ion-implantation energy range has been extended.  The specialized MOCVD simulator PROCOM (2/3D) has been enhanced so that it is more convenient to model incorporation of dopants and impurities. Most significantly, p-doping (Mg) in GaN growth has been demonstrated. This version also includes improvement in treatment of surface site occupancy during MOCVD growth. 

quantum dot light emitting diodes (QDot LED), quantum dot; photo detectors (QDot PD), quantum well infrared photodetectors (QWIP) and quantum cascade lasers (QC Lasers). Please see the PPT files in our download page for more details on quantum dot and quantum cascade models. The new version runs much faster (a factor of two) due to the use of new compilers. Also, users have the option of upgrading to 64 bit operating system for further performance improvements.

Among other relatively minor improvements:

• inclusion of triplet states in OLED models.
• simultaneous lasing of TE/TM modes in multi-mode simulation.
• convergence improvement for self-consistent MQW calculation.
• more accurate 2/3D ray tracing model for LED/OLED.
• implementation of utilities for parameter extract (such as slope/intercept)
• trap assisted tunneling model.
• use of analytical non-parabolic band model for Fermi statistics.

The improvements were based on customer requests. If you had made a request in the past, please contact Crosslight to check if such requests were implemented.

The new version also includes many enhancements of the GUI: the wizard now includes selection box for all parameters so that typing may be eliminated for most case. A new GUI called SolverManager presents simplified; solution control information in the form of EXCEL (good news for Excel lovers). A more flexible GeoEditor will allow easy design of complicated geometries such as those encountered in LED chips.

The new version is expected to be shipped within weeks. In the mean time, beta version is available for selected testing users through special arrangement.

For All Packages:

• Improvement of speed and convergence for most cases has been achieved through an upgraded multi-frontal sparse matrix solver and finely tuned internal mesh allocation near the heterojunctions.
• Simulation speed and stability have been enhanced for thermal model through an improved macro parameter updating procedure.
• The material macro now accepts a new data format: numerical table to represent multiple variable functions.Experimental data can now be directly used within the macro.
• A new option is available to increase the simulation speed through parallel computation using multiple CPU computers.This option is recommended for devices with large number of mesh points.
• The drift-diffusion transport model across a quantum well (QW) may be corrected to take into account non-equilibrium quantum transport effect such as direct fly-over and hot carrier escape from the QW. Such non-equilibrium corrections are expected to be significant for GaN-based QW's since they are thinner and deeper than their smaller bandgap counterparts.
• Optical gain profile within a complex MQW system has been improved so that it is convenient to model devices involving type-II MQW, such as infrared W-laser.
• A new option: multilayer optics analyzer (MOA) can be used as a powerful tool to perform spectral analysis of material/device under injection condition. Arbitrary polarization and angle of incidence can be conveniently controlled. We expect this option to be popular for modeling LED, OLED, RCLED and VCSEL.

Package Specific Improvements/New Features:

• Simulator engine has been reconfigured so that quantum wells may be placed on x-y planes. This way, user may conveniently set up material region with rounded boundaries. This may be convenient for the design of electrodes within a full 3D simulation (APSYS-3D, PICS3D).
• Interface between CSUPREM and APSYS has been established so that silicon process simulation data may be imported into APSYS. Several examples with imported data involving LDD MOSFET, MESFET, SOI and Ultra-Thin Oxide MOSFET have been demonstrated.
• OLED EL spectrum model has been incorporated into the OLED option. A Frenkel exciton model with phonon interaction has been used to provide a powerful tool for the design of OLED material (APSYS).
• Rectangle VCSEL can now be simulated within the VCSEL option. Rectangular coordinate system may be used to perform full 3D VCSEL simulation with arbitrary structure. Yes, multiple lateral mode effect may be taken into account (PICS3D).

GUI Improvements/New Features:

• LayerBuilder, Layer3d and GeoEditor have been upgraded to better handle 3D electrode design issues.
• GeoEditor3D is released so that arbitrary 3D geometry design may be achieved through graphic means.
• A new GUI module called Solver Manager can now be used to better control the simulation solver through graphic means instead of through text files.
• Speed of CrosslightView has also been improved.

1) Fixed a major bug for many-body (MB) gain enhancement model so that it can be applied to all material systems (including GaN-based wide bandgap MQW system). Some brief results of MB in GaAs/AlGaAs and InGaN/GaN quantum well systems are shown at this LINK.

2)More complete model for inhomogeneous broadening (bandgap tails states) has been implemented with the tails states included in carrier concentration.

3) Implemented single slit diffraction model for incident light beam on photosensitive devices.

4) Major improvement in CrosslightView: more efficient and more plotting features including AC analysis and band diagram.

5) Mesh edit/display feature in LayerBuilder. Major bug fixes in Layer3D regarding z-segment editing.

6) Release of the MacPlot program which may be used to view material macro parameters graphically.

Crosslight's version of SUPREM (or CSUPREM) not only inherits the essential physical models in the original version fromStanford, but it also contains substantial enhancements and extensions. Most significantly, the entire mesh system has been redesigned and extended. An interface to Crosslight's Geo3d module enables CSUPREM to perform full 3D process simulation.

As a result of innovative and effective software module interfacing, Crosslight is able to offer the fully supported process simulator at affordable prices. Effective and affordable CAD tools are increasingly important in controlling the explosive cost of the development and optimization of IC fabrication steps.

An additional benefit of using CSUPREM is that it provides input/output data interface with other well established simulators of Crosslight such as APSYS/Quantum-MOS and PROCOM. Proper doping profile is known to determine the accuracy of any device simulation.

For more details, please browse the PRODUCTS session of this website. CSUPREM will be available for free-trail starting in or around Oct. 2004.

PICS3D-VCSEL: Non-symmetric VCSEL multimode simulation.

Non-symmetric VCSEL with multiple-lateral mode competition model has been implemented. For this module, full-3D treatment with 3D-flow option should be used. For sample results of the new VCSEL feature, please check this [link].

PICS3D-VCSEL: Automatic VCSEL tuning module:Tune_vcsel

A challenge for many new VCSEL designers and new PICS3D-VCSEL users is to set layer thicknesses in a VCSEL so that it simultaneously satisfies the following requirements: a) the resonant wavelength is tuned to the material gain peak; b) the MQW active region is positioned near the peak of the standing waves to achieve maximum confinement factor. A new module is created to facilitate this process so that the optimal layer thicknesses may be chosen by the module according to the material gain spectrum and MQW locations. This helps speed up the process of setting up a new VCSEL from scratch.

All packages: Substantial improvement in k.p model for zinc-blende quantum well structures.

For the basic version, 6x6 k.p valence mixing model has been added. The improved 8x8 k.p option is now based on the solution of the original 8x8 Hamiltonian (without approximation involved in rotation transformation) with averaging over different k-directions for optical gain/carrier concentration computation. The effects of the remote bands have been included through the Kane parameter recently introduced in the material macros. Such an approach represents the most accurate solution in quantum well band structure model within the k.p theory. The 8x8 k.p model for zinc-blende quantum well has been compared with 6x6, 4x4 and parabolic band model for optical gain and lasing characteristics in new examples. For a sample of the comparison results, please check this [link].

All packages: Flexible data import/export for quantum well models.

The basic version now includes a flexible feature to export and import the following data in ASCII format: optical gain, refractive index change, and spontaneous recombination rate as a function photon energy, carrier concentration, hole/electron ration and temperatures. It is also possible to export/import k.p subbands and dipole moment as a function of k.

All packages: Tail states model for the Joint Density of States (JDOS)

Tail states in the bandgap due to impurity or to quantum well thickness fluctuation may be included in the joint density of states to adjust the shape of the gain or spontaneous emission spectra. For many LED spectrum, the tail states make the shape of the spontaneous emission spectrum more symmetric than in an ideal material model. For an example please check this [link].

All packages: Quinary material and enhanced material macros.

The material macro library in Crosslight's device simulators has been further enhanced. The software may now handle up to nine user-supplied macro function variables. As a result of the improvement, quinary materials can routinely be constructed and easily used in simulations. For quantum well and barrier consisting of quinary materials, more than six macro function variables are required. New macros include InGaAsNSb, InSb and InGaSb, among others.

All packages: Faster linear solver

Improved multi-frontal sparse linear matrix techniques with an improvement of about 40 percent in speed and increase in numerical solution stability. Depending on the ratio of linear/non-linear solution times, this translates into 10 to 30 percent total speed increase.

APSYS: Quantum well model for strained silicon MOS

The quantum-MOS option is now capable of treating strained silicon MOS. Mobility enhancement theory is based on quantum well valley splitting and intra-valley/inter-valley phonon-scattering effects. This Quantum-MOS option includes mobility enhancement model for uniaxially strained silicon quantum well channel as well as conventional biaxially strained silicon grown on relaxed SiGe (001). A new class of material macros called general_cx_strain has been established to describe strained silicon grown on relaxed SiGe. New macros include cx-SiGe/SiGe, cx-SiO2/SiGe and cx-ux-Si to describe silicon quantum well channel under various strain conditions. For a sample of our results for strained silicon quantum-MOS, please check out this [link].

APSYS-3D/PICS3D: More flexible geometry for full 3D simulation

Now we can bend an x-y plane in any form and in any shapes. This makes the 3D-flow option extremely powerful. For a bended structure, please check out [link].

All packages: Flexible band alignment control and type-II quantum wells

Quantum well alignment control is more flexible. In addition to the band offset ratio setting in older versions, users may now choose to define an absolute value of the conduction band discontinuity for the left and right barriers, respectively. Negative band discontinuity may be used to define type-II quantum wells. One may also choose to use electron affinity of bulk material to define all band alignments.

All packages: Enhanced quantum well (gain) preview module

The gain preview module (controlled by .gain file) is enhanced so that quantum well band structure with subband envelop function may be plotted in preview stage with the self-consistent option assuming an applied field.

LASTIP: More accurate front-back facet power calculation

Eliminated a design flaw that caused inaccurate power output for laser with highly non-symmetric front/back facets.

APSYS: Organic light emitting diode (OLED) option

A new option for OLED simulation has been implemented. Two or three dimensional OLED structure may be set up to compute all the physical properties of an OLED as in the case of the conventional LED. These include internal efficiency, extraction efficiency through ray-tracing, current and power versus voltage. With OLED modeling in mind, a new class of material type "organic" has been established in the material macro. For a sample of our results, please check this [link].

PICS3D: Improvements in photonic intergrated circuit model.

More efficient and stable solver introduced for SOA/WGPD with weak-reflection approximation. This version integrates BPM solver with SOA.

All packages: More stable self-heating model

More stable form of the Joule heating term has been introduced.

APSYS: Raytracing option enhanced

The raytracing option has been substantially enhanced:
a) Angular distribution of light is smoother;
b) Better data presentation according to standard spherical coordinate system;
c) New feature to plot LED light projection on a distant screen.
d) More flexible external packaging elements such as plate and dome have been added.
e) Capable of simulating structures with non-parallel facets.
For more details of the packaging model in the 3D-raytracing module, please check out this [link].

PICS3D-VCSEL: Finite difference time domain (FDTD) simulator module

The finite difference time domain (FDTD) simulator module is now available as a post-processing analyzer. It is a full vectorial solver capable of predicting complex vectorial modal behavior and assessing diffraction losses due to contacts and DBR's. The FDTD solver comes with the VCSEL option. For modal plot of a VCSEL, please check out this [link].

All packages: Significant improvement in graphical user interface (GUI)

The graphical user interface (GUI) in the release contains many improvements. These include better graphics in CrosslightView, and ability for SimuCenter to generate a series of projects based on variation of a single parameter (such as quantum well thickness).

• A new option of full 3D simulation is now available. The input geometry of the 3D is very flexible and can model reactor surfaces of any shapes through the bending of x-y planes into any surface function describable analytically or piece-wise analytically. An example of 3D mesh of a horizontal reactor is shown here and the 2D distribution of the growth rate from a full 3D simulation is illustrated here.
• Heat conduction within the solid walls of the reactor has been incorporated into 2D and 3D simulations so that distribution of temperature over the substrate can be calculated instead of being imported from a 3rd party model or has to be assumed constant.
• An efficient and reliable iterative linear solver has been implemented into the new version so that significant improvement in speed and memory requirements has been achieved.
• More examples and more detailed documentation on different reactor types and comparison with experimental data.

• All packages using "new_doping" model and thermal option:
  Fixed bug which caused non-convergence when "new_doping" combined with thermal model.
• All packages using thermal option:
  a) Improvement of numerical stability of Joule heating source;
  b) Inclusion of stimulated recombination as both radiation heat source and recombination heat source with improved accuracy and clearer physical model;
  c) Subtraction of background electrical field from the "j.e_model" heat source to resolve the problem of negative heating at low applied field for this model.
• All packages using tunneling option for Schottky contacts:
  Fixed bug of Schottky tunneling barrier when more than one material is involved.
• APSYS with LED application:
  Improve the way to compute spontaneous emission spectrum of LED.
• APSYS/PICS3D for photo-sensitive devices or waveguide PD:
  Corrected the sign problem of background absorption or passive layer absorption.
• APSYS:
  a) Added new quantum-MOS example with n-poly gate. Good agreement with experimental gate current for the new example was found.
  b) Rewrote and documented solar cell example in manual.
• LASTIP for multiple lateral mode simulation:
  Fixed bug in plotting far field of higher order lateral mode.
• APSYS/PICS3D for 3D-flow option:
  Fixed linear solver crash bug when mesh points in different segments were different.
• APSYS for 3D ray-tracing application:
  Fixed a bug in calculation of angular distribution of power printed in log data files.
• PICS3D for SOA application:
  Fixed a bug related to SOA background gain affecting power amplification at low power ranges.
• SimuCenter for all packages:
  Enhanced the file types the SimuCenter will recognize: For example, .sol is enhanced to .sol*, .plt to .plt*, etc.