Poisson takes a stack of semiconductor layers — each with its material, thickness and doping — and a surface boundary condition, and computes the equilibrium band diagram: the electrostatic potential, energy bands and carrier densities through the structure.
It solves Poisson’s equation at a single Fermi level. Two add-ons extend it: a Schrödinger solver that finds the quantised states in a region, and a capacitance–voltage sweep. Structures are saved as project files and read back for editing.
Scope. This is a zero-current, steady-state model. It gives you the electrostatics — where the bands sit and how the carriers distribute — but it does not simulate current flow or transport. Forward-biased, conducting junctions are outside what it can represent.
01Getting started
- What Poisson Does — and Doesn’t — the single-Fermi-level, zero-current model, and where its limits fall.
- The Main Window — a tour of the layer table, the control panel and the menus.
02Building a device
- The Layer Table — add, insert and remove layers; what each column means.
- Composition and Doping Gradients — grade alloy fraction or doping across a single layer.
- The Substrate Row — set a semi-infinite rear reference reservoir.
- The Materials Database — edit the materials file, add your own material, reveal and reset it.
03Boundary conditions and carriers
- Surface Boundary Conditions — schottky, ohmic, pinned, surface charge and contact bias, and what to enter.
- Contacts Under Bias — how a biased contact sets the carrier populations, and which structures fall out of scope.
- Carrier Calculations — default, no holes, no electrons and freeze minority.
- Temperature and Ionisation — set the temperature and choose full or partial dopant ionisation.
04Running the solve
- Mesh Spacing — trade accuracy against speed with the grid spacing.
- Running a Simulation — start a solve and read whether it converged.
05Reading results
- The Results Window — bands, carrier densities and sheet charges.
- The Plot Window — toggle lines, switch density to log or linear, open several plots.
- Sheet Resistance and Transport — the per-layer transport summary.
- Capacitance-Voltage — enable a C–V sweep and read the curve.
- Quantised States — find bound states in a region with the Schrödinger solver.
- Copying, Saving and Exporting — get results and the layer structure out of the tool.
06Reference
- Tips and Pitfalls — common surprises and how to read them.
- Worked Examples — walk through the bundled example structures.
- File Formats and Reference — project files, the materials file, menus and shortcuts.
Software Utilities 