InGaAs/AlInAs high-electron-mobility transistor

Last update: 2026-04-21

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Files for the tutorial located in nextnano++\examples

• HEMT_1D.nnp

• HEMT_2D.nnp

• HEMT_3D.nnp

Contents

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Introduction

This tutorial demonstrates how High Electron Mobility Transistors can be modelled with nextnano++.

HEMT structure

Input file: HEMT_1D.nnp

The structure consists of the following material layers:

	width [nm]	material
1		Schottky barrier 0.2 eV
2	10.0	\(In_{0.532}Ga_{0.468}As\)
3	25.0	\(Al_{0.477}In_{0.523}As\)
4	50.0	\(In_{0.532}Ga_{0.468}As\)
5	300.0	\(Al_{0.477}In_{0.523}As\)
6	300.0	InP

The conduction band edge profile without doping is plotted in Figure 350.

Figure 350 Calculated conduction band edge profile.

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

We obtain two eigenstates and their corresponding wave functions inside the HEMT channel which leads to a two-dimensional electron gas (2DEG), see Figure 351. The electron density is plotted in blue.

Figure 351 Calculated conduction band edge profile and probability densities.

In the file bias_00000/total_charges.txt we can find the integrated electron and hole densities. The total integrated density (from 10 nm to 100 nm) which can be measured experimentally is 1.87 \(\cdot\) 10¹² cm^-2 in agreement with the experiment. Most of the density is located between 45 nm and 95 nm.

2D/ 3D simulations

Input files: HEMT_2D.nnp, HEMT_3D.nnp

Input files for the same HEMT structure as in 1D, this time for a 2D and 3D simulations, are also available.

• 2D: rectangle of dimension 250 nm x 10 nm

• 3D: cuboid of dimension 250 nm x 10 nm x 10 nm