Spectral and polarization based imaging in deep-ultraviolet excited photoelectron microscopy

Area of Science:

• Condensed Matter Physics
• Materials Science
• Surface Science

Background:

• Atomically thin molybdenum disulfide (MoS2) is a crucial material in advanced electronics and optoelectronics.
• Characterizing buried MoS2 layers with high resolution is challenging using conventional imaging techniques.
• Understanding the optical properties of layered materials is essential for device performance.

Purpose of the Study:

• To develop and demonstrate a nanoscale spectral imaging technique for buried atomically thin MoS2.
• To utilize photoelectron emission microscopy (PEEM) for probing optical properties below the diffraction limit.
• To correlate photoemission signals with the optical response of the material stack.

Main Methods:

• Employing photoelectron emission microscopy (PEEM) with deep-ultraviolet (DUV) light excitation.
• Monitoring wavelength and polarization dependence of the photoelectron signal from buried MoS2.
• Comparing experimental photoemission yield data with classical optical theory simulations.

Main Results:

• Achieved nanoscale spectral imaging of MoS2 sandwiched between Al2O3 and SiO2.
• Demonstrated that PEEM can achieve resolutions below the photon wavelength by sensing electron response.
• Observed spatial variations in spectral and polarization dependence, correlating with MoS2 grains and defects.

Conclusions:

• Photoemission yield is a direct probe of UV-light-material interactions in complex stacks.
• PEEM modalities enable mapping of optical property variations at unprecedented length scales.
• This technique offers a powerful new tool for characterizing buried nanostructured materials.