Semiconductor Module Updates

For users of the Semiconductor Module, COMSOL Multiphysics® version 5.6 includes support for multicomponent wave functions and tensorial effective masses, new Lorentz Force and Rotating Frame features, and an improved drift-diffusion formulation for graded materials. Read more about these semiconductor features below.

Multicomponent Wave Function

The Schrodinger Equation interface has been expanded to support multicomponent wave functions and tensorial effective masses. With this new capability, there is a straightforward workflow for modeling multiband systems and particles with spins. You can see this functionality demonstrated in the k • p Method for Strained Wurtzite GaN Band Structure and A Silicon Quantum Dot in a Uniform Magnetic Field application examples.

Chart of a strained wurtzite GAN crystal's band structure with a blue line for HH, green for LH, red for CH, and teal circles to note the analytic points of each line. k dot p plot Band structure of a strained wurtzite GaN crystal.

Lorentz Force

This new feature adds the Lorentz force contribution to the kinetic momentum from the magnetic vector potential, useful for systems under the influence of magnetic fields. You can see this functionality demonstrated in the A Silicon Quantum Dot in a Uniform Magnetic Field application example.

The COMSOL Multiphysics UI showing the Model Builder, Lorentz Force feature settings for the Semiconductor Module, and 2D model results. Lorentz Force feature Probability density and kinetic momentum density of a silicon quantum dot in a magnetic field.

Rotating Frame

The new Rotating Frame feature adds a contribution to the Hamiltonian corresponding to a rotating frame, making it easy to analyze systems in a rotating reference frame. You can see this functionality demonstrated in the Vortex Lattice Formation in a Rotating Bose–Einstein Condensate application example.

Time evolution of the probability density of a rotating Bose–Einstein condensate showing the formation of a vortex lattice.

Wide Support for Eigenfrequency Analysis

The Eigenfrequency study is now supported for most of the AC/DC Module interfaces: Electric Currents, Electric Currents in Shells, Electric Currents in Layered Shells, Electrical Circuit, Electrostatics, and Magnetic Fields. In addition to supporting full-wave cavity mode analysis in the Magnetic Fields interface, it is possible to run eigenfrequency analyses with models involving electrical circuits. The eigenfrequency support is primarily developed for the AC/DC Module, but other modules that provide one of the affected physics interfaces will benefit from it too.

The COMSOL Multiphysics version 5.6 UI showing the Model Builder, Global Evaluation settings with the Data and Expressions sections expanded, and a probe plot for the eigenfrequency analysis of an RLC circuit. Eigenfrequency analysis example The resonance peak of a simple RLC circuit. The eigenfrequency and Q-factor are analyzed and compared to analytically determined values.

New and Enhanced Functionality for the Electrical Circuit Interface

For Time Dependent studies, the Electrical Circuit interface has been equipped with an "event-based" Switch feature. This allows you to model the "instantaneous" on-off switching of certain connections in the circuit. The switch can be current controlled, voltage controlled, or controlled by user-defined Boolean expressions.

Furthermore, Parameterized Subcircuit Definitions are added. Together with the Subcircuit Instance, these allow you to create your own building blocks containing smaller circuits, and use multiple parameterized variants of those in your larger circuit. Finally, the state, event, and solver machinery has been improved, especially the transient modeling of nonlinear (semiconductor) devices, which has become more robust.

The circuit improvements are primarily developed for the AC/DC Module, but other modules that provide access to the Electrical Circuit interface will benefit too. You can view the new functionality in these updated models:

Drift-Diffusion Formulation

The drift-diffusion formulation has been expanded for graded materials to include the effect of continuously varying effective density of states. (The quasi-Fermi level formulation already included this.)

New Tutorial Models

COMSOL Multiphysics® version 5.6 brings three new tutorial models to the Semiconductor Module.

k • p Method for Strained Wurtzite GaN Band Structure

Model of a strained wurtzite crystal with three layers for the valence bands with computed values shown in a rainbow color table and analytic solution in a gray wireframe. Strained wurtzite GaN crystal Band structure of a strained wurtzite GaN crystal.

Application Library Title:
k_dot_p_method_strained_wurtzite_gan_band_structure
Download from the Application Gallery

A Silicon Quantum Dot in a Uniform Magnetic Field

A model of a silicon quantum dot shown in red, orange, green, and blue, and a magnetic field shown as magenta arrows. Silicon quantum dot The 8th excited state of a silicon quantum dot in a magnetic field.

Application Library Title:
si_quantum_dot_in_uniform_magnetic_field
Download from the Application Gallery

Vortex Lattice Formation in a Rotating Bose-Einstein Condensate

A grayscale model of the probability density versus time of a rotating Bose-Einstein condensate revealing a vortex lattice from 20 ms to 600 ms. Vortex lattice model time evolution Time evolution of the probability density of a rotating Bose–Einstein condensate showing the formation of a vortex lattice.

Application Library Title:
vortex_lattice_formation_in_a_rotating_bose_einstein_condensate
Download from the Application Gallery