Bandgap mapping for III-V quantum well by electron spectroscopy imaging

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Bandgap mapping is crucial for understanding semiconductor inhomogeneity.
• Previous methods lacked sufficient spatial resolution for nanoscale analysis.
• III-V semiconductors and quantum well structures present unique characterization challenges.

Purpose of the Study:

• To develop and demonstrate advanced electron spectroscopy imaging (ESI) techniques for bandgap mapping.
• To accurately determine the bandgap energy distribution in GaN/AlN quantum-well structures.
• To improve the spatial resolution and accuracy of bandgap energy measurements.

Main Methods:

• Utilized phase correlation for precise image registration in ESI series.
• Employed fast Fourier transform interpolation to enhance energy dispersion.
• Developed an iterative multivariable least square algorithm for fitting density of states.
• Applied threshold filtering to quantify bandgap energies in specific regions.

Main Results:

• Successfully mapped the bandgap energy distribution in GaN/AlN quantum wells.
• Achieved high spatial resolution for nanoscale inhomogeneity analysis.
• Determined average bandgap energies: AlN (5.62 ± 0.35 eV) and GaN (3.87 ± 0.36 eV).
• Demonstrated analysis accuracy comparable to half the ESI energy resolution.

Conclusions:

• The refined ESI techniques enable detailed bandgap mapping of quantum well structures.
• The developed methods provide accurate quantitative analysis of bandgap energy variations.
• This approach offers significant advancements in semiconductor characterization at the nanoscale.