# Workshop¶

A few nextnano workshops were held in the past using the material presented below. The following tutorials are suited to learn more about the nextnano software.

## pn junction¶

recommended

https://www.nextnano.com/nextnano3/tutorial/1Dtutorial_pn_junction.htm

pn_junction_GaAs_1D*.in (nextnano++ & nextnano³)
pn_junction_GaAs_2D*.in (nextnano++ & nextnano³)
Summary

This example is rather simple.

Model used

1D; Poisson equation

Try to reproduce the results in the figures. Run and plot the 2D files.

Challenge

To plot two different graphs, i.e. data files, simultaneously. Export the graph containing two different graphs to gnuplot. Export a 2D file to gnuplot.

Duration

10 minutes

## Double Quantum Well¶

recommended

https://www.nextnano.com/nextnano3/tutorial/1Dtutorial_DoubleQW.htm

DoubleQuantumWell_*.in (nextnano++ & nextnano³)
Summary

This example teaches quantum physics: bonding and anti-bonding wavefunctions.

Model used

1D; Schrödinger equation

Try to reproduce the results in the figures.

Challenge

Perform a parameter sweep using nextnanomat ’s Template feature and do a post-processing using nextnanomat to reproduce the figure Eigenvalues vs. barrier width. Export the graph to gnuplot.

Duration

20 minutes

## Schrödinger-Poisson - A comparison to the tutorial file of Greg Snider’s code¶

recommended

https://www.nextnano.com/nextnano3/tutorial/1Dtutorial_SchroedingerPoisson.htm

Greg_Snider_MANUAL_*.in (nextnano++ & nextnano³)
Summary

This example is relatively easy.

Model used

1D; self-consistent Schrödinger-Poisson

Try to reproduce the results in the figures.

Challenge

To plot two different graphs, i.e. data files, simultaneously. Understand where you find eigenvalues and wavefunctions. Export the graph containing two different graphs to gnuplot.

Duration

20 minutes

## InGaAs Multi-Quantum Well Laser diode¶

very important

https://www.nextnano.com/dokuwiki/doku.php?id=nnp:1d_ingaas_laser_diode

LaserDiode_InGaAs_1D_cl_nnp.in (nextnano++)
LaserDiode_InGaAs_1D_qm_nnp.in (nextnano++)
Summary

This example teaches how to apply a bias and solve the coupled system of Schrödinger, Poisson and Current equations.

Model used

1D; selfconsistent Schrödinger–Poisson–current

Try to reproduce some of the figures.

Challenge

To understand how a laser works. Plot the recombination rates and the classical emission spectrum. Do a parameter sweep, e.g. number of wells, doping, alloy content and see how the classical emission spectrum changes. Plot the wavefunctions. Compare the classical density vs. the quantum density for the same bias, e.g. for 1 V where the quantum wells contain a significant density. Plot the convergence log files on a logarithmic scale. Plot the current densities, IV curve, doping profile, …

Duration

40 minutes

## Optical interband transitions in a quantum well - Matrix elements and selection rules¶

optional

https://www.nextnano.com/nextnano3/tutorial/1Dtutorial_OpticalTransitions.htm

1DQW_interband_matrixelements_*.in (nextnano++ & nextnano³)
Summary

This example teaches how to calculate the spatial overlap of electron and hole wavefunctions and their transition energy.

Model used

1D; Schrödinger equation

Try to reproduce the results in the figures.

Challenge

Compare the infinite vs. finite quantum well to understand selection rules.

Duration

10 minutes

## Wurtzite¶

optional

https://www.nextnano.com/nextnano3/tutorial/1Dtutorial11.htm

wurtzite*.in (nextnano++ & nextnano³)
Summary

This example is relatively easy and discusses strain, piezo any pyroelectricity.

Model used

1D; strain and Poisson equation

Try to reproduce the results in the figures.

Challenge

To understand the peculiarities of wurtzite.

Duration

20 minutes

## Two-dimensional electron gas in an AlGaN/GaN field effect transistor¶

optional

https://www.nextnano.com/nextnano3/tutorial/1Dtutorial_AlGaN_GaN_FET.htm

Jogai_AlGaNGaN_FET_JAP2003*.in (nextnano++ & nextnano³)
Summary

This example is nice. Try to reproduce some of the figures.

Model used

1D; strain, selfconsistent Schrödinger–Poisson

Try to reproduce the results in the figures.

Challenge

Can you do a parameter sweep using nextnanomat ’s Template feature and plot the 2DEG density vs. $$\text{Al}_x\text{Ga}_{1-x}\text{N}$$ thickness?

Duration

20 minutes

## $$\mathbf{k} \cdot \mathbf{p}$$ dispersion in bulk GaAs (strained / unstrained)¶

https://www.nextnano.com/nextnano3/tutorial/1Dtutorial13.htm

bulk_kp_dispersion_GaAs*.in (nextnano++ & nextnano³)
Summary

This example teaches the $$\mathbf{k} \cdot \mathbf{p}$$ band structure.

Model used

bulk; strain, $$\mathbf{k} \cdot \mathbf{p}$$

Try to reproduce some of the figures: Plot the single-band, the 6-band dispersion and the 8-band $$E(k)$$ dispersion in the same plot. Do the same for the strained case to see how strain alters the band structure.

Challenge

To understand the $$\mathbf{k} \cdot \mathbf{p}$$ method.

Duration

15 minutes

## $$\mathbf{k} \cdot \mathbf{p}$$ dispersion in bulk unstrained ZnS, CdS, CdSe and ZnO (wurtzite)¶

https://www.nextnano.com/nextnano3/tutorial/1Dtutorial_bulk_6x6kp_dispersion_IIVI.htm

bulk_6x6kp_dispersion_ZnO*.in (nextnano++ & nextnano³)
Summary

This example teaches the $$\mathbf{k} \cdot \mathbf{p}$$ valence band structure for wurtzite materials.

Model used

bulk; strain, $$\mathbf{k} \cdot \mathbf{p}$$

Try to reproduce some of the figures.

Challenge

To understand the $$\mathbf{k} \cdot \mathbf{p}$$ method for wurtzite.

Duration

5 minutes

## $$\mathbf{k} \cdot \mathbf{p}$$ dispersion in bulk unstrained, compressively and tensilely strained GaN (wurtzite)¶

https://www.nextnano.com/nextnano3/tutorial/1Dtutorial_strained_GaN_dispersion.htm

bulk_kp_dispersion_GaN_unstrained*.in (nextnano³)
Summary

This example teaches the $$\mathbf{k} \cdot \mathbf{p}$$ valence band structure for wurtzite materials.

Model used

bulk; strain, $$\mathbf{k} \cdot \mathbf{p}$$

Try to reproduce some of the figures.

Challenge

To understand the $$\mathbf{k} \cdot \mathbf{p}$$ method for wurtzite.

Duration

10 minutes

## $$\mathbf{k} \cdot \mathbf{p}$$ energy dispersion of holes in a quantum well¶

https://www.nextnano.com/nextnano3/tutorial/1Dtutorial8.htm

1Dwell_GaAs_AlAs_*.in (nextnano++ & nextnano³)
Summary

This example teaches the $$\mathbf{k} \cdot \mathbf{p}$$ model: $$E\left(k_{\parallel}\right)$$ dispersion.

Model used

1D; $$\mathbf{k} \cdot \mathbf{p}$$ Schrödinger equation

Try to reproduce some of the figures.

Challenge

To understand the $$\mathbf{k} \cdot \mathbf{p}$$ features for heterostructures.

Duration

20 minutes

## $$\mathbf{k} \cdot \mathbf{p}$$ energy dispersion of an unstrained GaN QW embedded between strained AlGaN layers¶

https://www.nextnano.com/nextnano3/tutorial/1Dtutorial_GaN_AlGaN_QW_dispersion.htm

1DGaN_AlGaN_QW_k_zero_*.in (nextnano++ & nextnano³)
Summary

This example teaches the $$\mathbf{k} \cdot \mathbf{p}$$ model: $$E\left(k_{\parallel}\right)$$ dispersion.

Model used

1D; $$\mathbf{k} \cdot \mathbf{p}$$ Schrödinger equation

Try to reproduce some of the figures.

Challenge

To understand the $$\mathbf{k} \cdot \mathbf{p}$$ features for heterostructures.

Duration

20 minutes

## Capacitance-Voltage curve of a metal–insulator–semiconductor (MIS) structure¶

https://www.nextnano.com/nextnano3/tutorial/1Dtutorial_MIS_CV.htm

1DMIS_CV_Fermi_*.in (nextnano++ & nextnano³)
Summary

This example teaches how to apply a bias without solving the current equation.

Model used

1D; selfconsistent Schrödinger–Poisson

Try to reproduce some of the figures.

Challenge

To understand how to integrate charge carrier densities in specific regions.

Duration

20 minutes

## Core-shell nanowire¶

recommended

Schrödinger equation of a two-dimensional core-shell structure

Hexagonal 2DEG - Two-dimensional electron gas in a delta-doped hexagonal shaped GaAs/AlGaAs nanowire heterostructure

https://www.nextnano.com/nextnano3/tutorial/2Dtutorial_core_shell_circle_hexagon.htm

2DGaAs_AlGaAs_*.in (nextnano++ & nextnano³)
2D_Hexagonal_Nanowire_2DEG*.in (nextnano++ & nextnano³)
Summary

This example teaches how to perform a 2D simulation.

Model used

2D; Schrödinger equation, selfconsistent Schrödinger–Poisson

Try to reproduce some of the figures.

Challenge

To understand how to visualize 2D results and how to export them to gnuplot. Plot the geometry together with the electron density of the modulation doped core-shell nanowire in one graph.

Duration

15 minutes

## Quantum dot molecule¶

https://www.nextnano.com/nextnano3/tutorial/3Dtutorial_QD_molecule.htm

3DQD_molecule_cuboid_asymmetric_*.in (nextnano++ & nextnano³)
Summary

This example teaches how to apply an electric field in a 3D simulation.

Model used

3D; Schrödinger equation

Try to reproduce some of the figures.

Challenge

To understand how to visualize 3D results and how to export them to Paraview.

Duration

10 minutes

## Energy levels in a pyramidal shaped InAs/GaAs quantum dot including strain and piezoelectric fields¶

https://www.nextnano.com/nextnano3/tutorial/3Dtutorial_QD_pyramid.htm

3DInAsGaAsQDPyramid_PryorPRB1998_10nm_*.in (nextnano++ & nextnano³)
Summary

This example teaches how to calculate and plot strain, piezoelectric charge densities and wavefunctions in a 3D simulation.

Model used

3D; strain equation, Poisson equation, Schrödinger equation

Try to reproduce some of the figures.

Challenge

To understand how to visualize 3D results and how to export them to Paraview.

Duration

20 minutes

## Single-electron transistor - laterally defined quantum dot¶

https://www.nextnano.com/nextnano3/tutorial/3Dtutorial_SET_lateral_QD.htm

SET_Scholze_IEEE2000_*.in (nextnano++ & nextnano³)
Summary

This example teaches how a gate geometry depletes the 2DEG density locally.

Model used

1D, 3D; Poisson equation, Schrödinger equation, selfconsistent Schrödinger–Poisson

Try to reproduce some of the figures.

Challenge

To understand how to visualize 3D results and how to export them to Paraview.

Duration

15 minutes

Note

Search through

and simulate the topics that are of interest for you.

Important nextnanomat features that you should learn

• Tree View vs. List View

• Parameter sweeps using Template

• Parameter sweep post-processing using Template

• Postprocessing using nextnanopy

• Multi-Parameter sweeps using Template (beta)

• Batch list

• Exporting 2D slices of 3D data

• Exporting 1D slices of 2D/3D data

• Export to .vtr

• Exporting 3D data to Paraview

• Open files with notepad++, Origin, …

• Plotting several graphs (Overlay)

• Plotting several graphs in 2D/3D (Overlay)

• Zoom feature

• SOFT_KILL feature

• Display options

• Tools Options

• HTCondor Cloud Computing

• In principle you can run also you own software with nextnanomat. nextnanomat can run any executable either locally or on HTCondor.

• How to access online documentation and how it is structured.

• Which features are you missing?

If you have any comments or suggestions regarding this workshop material, please send your feedback to support [at] nextnano.com. We really appreciate your feedback on errors, broken links, typos, …