# nextnano.NEGF - Software for Quantum Transport

### nextnanomat

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### nextnano++

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### nextnano GmbH

negf:the_nextnano.negf_software

# The nextnano.NEGF software for Quantum Transport

This website describes the nextnano.NEGF software (previously called nextnano.QCL), a NEGF quantum transport code written by Thomas Grange. The nextnano.NEGF software has been developed to simulate electron dynamics in heterostructures like superlattices and quantum cascade lasers (QCLs). It can also be used to simulate absorption spectra in quantum wells (QWs) and transport in resonant tunneling diodes (RTDs).

The software calculates current-voltage characteristics and gain/absorption spectra.

This software is based on a quantum transport method that follows the nonequilibrium Green's function (NEGF) framework. The code can be executed using the nextnanomat software.

### Which scattering mechanisms are included?

• Longitudinal polar-optical phonon scattering (polar LO phonon scattering)
• Acoustic phonon scattering
• Charged impurity scattering
• Interface roughness scattering
• Alloy scattering
• Electron-electron scattering

### How do I obtain the nextnano.NEGF code?

Please download it from here. Additionally, it is strongly recommend to contact support@nextnano.com and inform us that you are interested in this tool. We can then assist you and provide new updates to you.

### How do I execute nextnano.NEGF?

Open the nextnanomat GUI, open a nextnano.NEGF input file and press the Run button.

nextnano.NEGF.exe <input file name> <output folder name> <material database name> <License file name>

Example:
nextnano.NEGF.exe "..\nextnano.NEGF sample files\MidIR_QCL_YuSlivkenRazeghi_SST2010.xml" "..\Output" "..\Material_Database.xml" "..\License_nnQCL.lic"

Optional: the argument “–threads 2” can be appended to the command line to limit the number of threads to e.g. 2.

### Are there any tutorial input files available?

• Tutorial - GaAs/AlGaAs THz QCL
Terahertz quantum cascade lasers operating up to ~ 200 K with optimized oscillator strength and improved injection tunneling
S. Fathololoumi, E. Dupont, C.W.I. Chan, Z.R. Wasilewski, S.R. Laframboise, D. Ban, A. Mátyás, C. Jirauschek, Q. Hu, H. C. Liu
Optics Express 20, 3866 (2012)
• Tutorial - InGaAs/InAlAs Mid-IR QCL
Injector doping level-dependent continous-wave operation of InP-based QCLs at λ = 7.3 µm above room temperature
J. S. Yu, S. Slivken, M. Razeghi
Semiconductor Science and Technology 25, 125015 (2010)

Further tutorials can be found here: Tutorials

### Where can I find some background on the implemented physics?

The NEGF method for QCLs is decribed in the following publications where the nextnano.NEGF code was used.

A good introduction is also the tutorial talk Modeling electron transport in quantum cascade lasers given by Thomas Grange at the International Quantum Cascade Laser School and Workshop (Cassis/France, 2018).

The nextnano.NEGF software has been developed by Thomas Grange. It is written in C#. For publications of Thomas Grange, see his profile on Google Scholar.

The nextnano.NEGF software is distributed by the nextnano GmbH.