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COMSOL Multiphysics® 6.0 Release Highlights

Semiconductor Module Updates

For users of the Semiconductor Module, COMSOL Multiphysics® version 6.0 includes functionality for transition between discrete trap energy levels, the ability to add contact resistance to metal contacts, and new heterojunction heat source functionality for thermal modeling. Read more about the Semiconductor Module updates below.

Transition Between Discrete Levels

A new Transition Between Discrete Levels feature is available as an attribute to the three trap-assisted recombination features (domain, boundary, and heterointerface) when the explicit trap option is selected and more than one discrete trap energy levels are created. This feature allows you to specify the decay lifetime between the trap levels and to simulate the transition between the quantized levels of quantum wells and/or quantum dots by treating them as trap levels. You can view this new feature in the A Solar Cell with InAs Quantum Dots Embedded in AlGaAs/GaAs Quantum Wells tutorial model.

A closeup view of the COMSOL Multiphysics UI showing the Model Builder with the Transition Between Discrete Levels node highlighted, the corresponding Settings window, and 1D plot in the Graphics window.
A solar cell model using the new transition feature to model the transition between the comprising quantum well and quantum dots.

Contact Resistance

A new Contact resistance option has been added to the Metal Contact boundary condition for both Ohmic and Schottky contact types and all five driving modes: voltage, current, power, circuit current, and circuit voltage. This feature can be enabled by selecting the Contact resistance check box (disabled by default) in the Settings window. This allows more realistic and convenient modeling of metal contacts. The A Cross-Bridge Kelvin Resistor Model for the Extraction of Specific Contact Resistivity tutorial model shows this new option.

A cross-bridge Kelvin resistor model showing the electric potential in the Prism color table and the current density shown in arrows and streamlines.
Electric potential (color) and current density (arrows and streamlines) of a cross-bridge Kelvin resistor for contact resistance measurement.

Klaassen Unified Mobility Model (LIC)

The Semiconductor interface now includes a Klaassen Unified Mobility Model feature (sometimes referred to as Philips unified mobility model) available through the Semiconductor Material Model node. In this model, the total carrier mobility is given by combining the lattice (L), donor (I), acceptor (I), and carrier–carrier (C) scattering effects. This mobility model also includes the screening of impurities by charge carriers and clustering of impurities at high doping levels. Both the Trench-Gate IGBT 3D and Trench-Gate IGBT 2D tutorial models show this new functionality.

A 3D trench-gate IGBT model showing the electron concentration in the Prism color table and current streamlines.
A model of an IGBT incorporating the Klaassen Unified Mobility Model feature.

Heterojunction Heat Source

The Joule heating contribution to the boundary heat sources at heterojunctions has been included in the built-in variables of the Semiconductor interface. This makes it easier to perform coupled thermal analysis of heterostructures.

New Default Solver

A new physics-suggested solver sequence has been added to the Semiconductor interface to streamline the study setup for models with field-dependent mobility and/or impact ionization generation. These existing Application Library models are now more efficient with the new solver sequence:

View screenshot

Reuse of Solution for Parametric Eigenvalue Problems

It is now possible to select the start vectors when solving parametric eigenvalue problems. This functionality can save computational time for eigenvalue problems with solutions that are smoothly varying with a change in the parameter. Examples can be found in models that use the Schrödinger-Poisson interface. With the Eigenvalue search method set to Manual, you can often reduce the number of iterations by at least 50%.

View screenshot

Trapping Features

A new option to specify additional electron and hole capture rates has been added to the Discrete Energy Level attribute for the trap-assisted recombination features (domain, boundary, and heterointerface), when the explicit trap option is selected. The Continuous Energy Levels feature has been enhanced by expanding the range of the trap energy levels outside of the band gap and allowing the capture probability to depend on the trap energy level. The trapping feature for the density-gradient formulation has been enhanced with the new option of solving for the trap occupancy (as opposed to the trap Fermi level).

Mobility Models

The Caughey-Thomas Mobility Model has been enhanced with several new options for the formulation of the driving forces, adding versatility for users interested in different types of driving forces.

View screenshot

Metal Contacts

A new built-in global variable for the average terminal current density has been added for the Metal Contact boundary condition, making it convenient to obtain scaling-independent output quantities for comparison purposes.

New and Updated Tutorial Models

COMSOL Multiphysics® version 6.0 brings several new and updated tutorial models to the Semiconductor Module.

Surface-Trap-Induced Hysteresis in an InAs Nanowire FET, a Density-Gradient Analysis

A 1D plot showing the hysteresis behavior with the total conductance on the y-axis and gate voltage on the x-axis.
Hysteresis behavior of the conductance versus gate voltage due to surface traps.

Application Library Title:
inas_nanowire_traps_hysteresis_density_gradient
Download from the Application Gallery

A Cross-Bridge Kelvin Resistor Model for the Extraction of Specific Contact Resistivity

A cross-bridge Kelvin resistor model showing the electric potential in the Prism color table and the current density shown in arrows and streamlines.
Electric potential (color) and current density (arrows and streamlines) of the cross-bridge Kelvin resistor.

Application Library Title:
cross_bridge_kelvin_resistor_contact_resistivity
Download from the Application Gallery

A Solar Cell with InAs Quantum Dots Embedded in AlGaAs/GaAs Quantum Wells

A 1D plot showing the occupation of quantum dot states at three different light power levels.
Occupation of quantum dot states as a function of the 1300 nm light power at three different 780 nm light power levels.

Application Library Title:
dot_in_well_solar_cell
Download from the Application Gallery

Trench-Gate IGBT 2D

A 2D plot showing the electron density in the Prism color table and black and white streamlines representing the current densities.
Electron density (color), electron current density streamline (gray), and hole current density streamline (black) in the MOS region of the IGBT.

Application Library Title:
trench_gate_igbt_2d
Download from the Application Gallery

Trench-Gate IGBT 3D

A 3D trench-gate IGBT model showing the electron concentration in the Prism color table and current streamlines.
Electron density (Prism color table), electron current density streamline (light blue), and hole current density streamline (yellow) in the MOS region of the IGBT.

Application Library Title:
trench_gate_igbt_3d
Download from the Application Gallery

MOSCAP 1D

A 1D plot showing a single blue line and single green line representing the C-V curves for the low-frequency and high-frequency.
C-V curves for the low-frequency and high-frequency cases of a metal-oxide silicon capacitor. This model has been expanded to demonstrate how to compute the differential capacitance using metal contacts where the terminal charge is not readily available.

Application Library Title:
moscap_1D
Download from the Application Gallery

MOSCAP 1D Small Signal

A 1D plot showing a single blue and single green line representing the C-V curves for the low- and high-frequency cases of a simple 1D model.
C-V curves for the low- and high-frequency cases of a simple 1D model of a metal-oxide silicon capacitor. This model has been expanded to demonstrate how to compute the differential capacitance using metal contacts where the terminal charge is not readily available. The mesh has also been improved for a better compromise between discretization error and roundoff error.

Application Library Title:
moscap_1d_small_signal
Download from the Application Gallery

Interface Trapping Effects of a MOSCAP

A 1D plot showing a single blue line for the computed terminal capacitance and a green line for the equivalent parallel conductance.
The computed terminal capacitance (Cm) and equivalent parallel conductance (Gp) as functions of the gate voltage (Vg) show the same qualitative behavior with comparable magnitudes of experimental data. The mesh in this model has been improved for a better compromise between discretization error and roundoff error.

Application Library Title:
moscap_1d_interface_traps
Download from the Application Gallery

Thermal Analysis of a Bipolar Transistor

A 2D plot showing the voltage and carrier currents (top) and the temperature distribution and heat flux (bottom).
Voltage and carrier currents for a bipolar transistor device operating in active-forward configuration (top), along with the corresponding temperature distribution and heat flux (bottom). This model has been updated to use the available temperature and heat source items in the drop-down menus for the temperature and heat source couplings, as opposed to entering the corresponding variables manually.

Application Library Title:
bipolar_transistor_thermal
Download from the Application Gallery