1.21. Interband tunneling current in a highly-doped nitride heterojunction

Author: Takuma Sato

Introduction

We compute interband tunneling current through a highly-doped heterojunction by nextnano++ simulation and Python postprocessing. We follow the methods in the following publication, using less approximations whereever possible:

Jean-Yves Duboz and Borge Vinter. Theoretical estimation of tunnel currents in hetero-junctions: The special case of nitride tunnel junctions

This tutorial uses the Python script in the nextnanopy repository

  • nextnanopy/templates/InterbandTunneling_Duboz2019_nnp.py

to automate the simulation of the nextnano++ input file (in the sample input file folder of nextnano installation)

  • InterbandTunneling_Duboz2019_nnp.in

and post-calculation of interband tunneling current.

For the details of the formulation and the algorithm in the Python script, see

  • nextnanopy/templates/InterbandTunneling_Duboz2019_formulation.pdf

Results

The structure is an AlGaN/GaN p-i-n junction with 2 nm GaN interlayer.

The energy overlap between the hole states and electron states increases as the bias, leading to larger tunnel current.

../../_images/bandedge_02.png
../../_images/bandedge_07.png

The Python script calculates dipole matrix elements from the simulation results:

../../_images/Dipole_matrix_element.png

from which we obtain the tunnel current as a function of bias:

../../_images/TunnelCurrent_vs_bias.png

Figure 1.21.1 Interband tunneling current in a nitride p-i-n junction. Following the paper, backward bias is taken to be positive in this plot.

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