Infrared Near-Field Spectroscopy of AlGaN/GaN Heterostructures for Probing Two-Dimensional Electron Gas.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Spectroscopy

Background:

• Two-dimensional electron gases (2DEGs) are critical for advanced electronic devices.
• AlGaN/GaN heterostructures host 2DEGs essential for high-power electronics and sensors.
• Characterizing 2DEGs at the nanoscale is challenging but vital.

Purpose of the Study:

• To employ infrared near-field spectroscopy (nano-FTIR) for noninvasive characterization of 2DEGs in AlGaN/GaN heterostructures.
• To demonstrate the capability of nano-FTIR to probe 2DEG properties with nanometric resolution.
• To validate the use of nano-FTIR for studying materials relevant to electronic devices.

Main Methods:

• Utilized infrared near-field spectroscopy (nano-FTIR) for nanoscale chemical and physical property probing.
• Applied analytical calculations based on the finite dipole model to interpret spectral data.
• Performed hyperspectral imaging on cross-sectional samples to visualize the 2DEG distribution.

Main Results:

• Nano-FTIR spectra, specifically higher harmonic amplitude and phase, showed sensitivity to 2DEG carrier concentration.
• Analytical models incorporating the 2DEG layer were essential for matching experimental spectral features.
• Hyperspectral imaging provided a visual map of the 2DEG within the heterostructure.

Conclusions:

• Nano-FTIR is a powerful tool for characterizing 2DEGs in AlGaN/GaN heterostructures with nanometric resolution.
• The technique operates effectively under ambient conditions, expanding its applicability.
• This method offers a noninvasive approach to studying critical components of electronic devices.