# nextnano3 - Tutorial

## HEMT structure (High Electron Mobility Transistor)

Authors: Stefan Birner

```-> HEMT_1D_nn3.in / *_nnp.in - ```input file for the nextnano3 and nextnano++ software (1D simulation)``` -> HEMT_2D_nn3.in -> HEMT_3D_nn3.in```

## HEMT structure

• This input file simulates a HEMT structure:``` HEMT_1D_nn3.in```
• It consists of:

at    10 nm: Schottky barrier of 0.2 eV
10 - 20 nm: In0.532Ga0.468As
20 - 45 nm: Al0.477In0.523As
45 - 95 nm: In0.532Ga0.468As
95 - ... nm: Al0.477In0.523As
The structure is grown on InP. There is no strain as everything is lattice matched. (Nevertheless, we still calculate the strain.)

• Now we add at x = 35 nm a silicon delta doping of 4.5 * 1012 cm-2 which leads to band bending.
Instead of choosing a delta doping we specify a constant doping of 1.5 * 1020 cm-3 that extends over 0.3 nm.
(1.5 * 1020 cm-3 * 3 * 10-8 cm = 4.5 * 1012 cm-2)

```\$doping-function  ... \$end_doping-function \$impurity-parameters  ... \$end_impurity-parameters ```We obtain two eigenstates and their corresponding wave functions inside the HEMT channel which leads
to a two-dimensional electron gas (2DEG). The electron density is plotted in blue.

• In the file` densities/int_el_dens1D.dat `we can find the integrated density in each region cluster.
The total integrated density (from 10 nm to 100 nm) which can be measured experimentally is thus
2.19 * 1012 cm-2 in agreement with the experiment. Most of the density is located between 45 nm and 95 nm, namely 2.05 * 1012 cm-2.

### 2D/3D simulations

```-> HEMT_2D_nn3.in -> HEMT_3D_nn3.in```

Input files for the same HEMT structure as in 1D, but this time for a 2D and 3D simulation are also available.
==> 2D: rectangle of dimension 250 nm x 10 nm
==> 3D: cuboid     of dimension 250 nm x 10 nm x 10 nm

 If you need support, or input files that are not included in the installation folder, or if you have suggestions on how we can improve our website or tutorials, please submit a Support Ticket.