Overcoming diffusion-related limitations in semiconductor defect imaging with phonon-plasmon-coupled mode Raman...

Area of Science:

• Materials Science
• Semiconductor Physics
• Optoelectronics

Background:

• Carrier diffusion is critical for semiconductor device performance (solar cells, photodetectors).
• Structural defects limit device potential, and large carrier diffusion lengths can obscure defect details.
• Photoluminescence (PL) imaging resolution is limited by carrier diffusion length, not optical limits.

Purpose of the Study:

• To demonstrate Raman imaging of LO phonon-plasmon-coupled modes for enhanced spatial resolution in defect analysis.
• To overcome the resolution limitations imposed by carrier diffusion in optical imaging techniques.
• To enable simultaneous and independent determination of carrier properties near defects.

Main Methods:

• Utilized Raman imaging targeting the LO phonon-plasmon-coupled mode.
• Employed diffraction-limited optics for high-resolution imaging of defects in Gallium Arsenide (GaAs).
• Combined Raman imaging with Photoluminescence (PL) imaging.

Main Results:

• Achieved a 10-fold improvement in spatial resolution for defect imaging compared to conventional methods.
• Recovered the intrinsic spatial resolution of the optical system, independent of carrier diffusion length.
• Successfully mapped the spatial dependence of electron density, hole density, radiative, and non-radiative recombination rates near a dislocation-like defect.

Conclusions:

• Raman imaging of LO phonon-plasmon-coupled modes offers superior spatial resolution for semiconductor defect analysis.
• This technique overcomes the fundamental resolution limits imposed by carrier diffusion in PL imaging.
• The combined Raman and PL approach provides unprecedented simultaneous characterization of defect-related carrier dynamics.