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Nanoelectronic Modeling Lecture 32: Strain Layer Design through Quantum Dot TCAD

By Gerhard Klimeck1, Muhammad Usman1

1. Electrical and Computer Engineering, Purdue University, West Lafayette, IN

Published on


This presentation demonstrates the utilization of NEMO3D to understand complex experimental data of embedded InAs quantum dots that are selectively overgrown with a strain reducing InGaAs layer. Different alloy concentrations of the strain layer tune the optical emission and absorption wavelength of the quantum dots. The role of the non-linear strain behavior ovserved in the experimental data is explored in NEMO3D. The simulation engine serves as a virtual microscope to understand the interplay of disorder, strain, and quantum dot shape.

Learning Objectives:

  1. Objective:
    1. Optical emission at 1.5μm without GaN
    2. Understand experimental data on QD spectra in selective overgrowth
  2. Approach:
    1. Model large structure
    2. 60nm x 60nm x 60nm
    3. 9 million atoms
    4. No changes to the published tight binding parameters
  3. Result:
    1. Match experiment remarkably well
      1. Strain
      2. change in quantum dot aspect ratio
    2. Quantitative model of complex system
    3. Studied sensitivity to experimental imperfections – small variations
    4. Effective mass theories provided the wrong guidance



Università di Pisa, Pisa, Italy

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