Breathing Mode's Temperature Coefficient Estimation and Interlayer Phonon Scattering Model of Few-Layer Phosphorene

Area of Science:

• Condensed matter physics
• Materials science
• Nanotechnology

Background:

• Raman spectroscopy is crucial for characterizing multilayer phosphorene, estimating layer numbers, and understanding interlayer thermal coupling.
• The temperature coefficient of phosphorene's breathing modes (Raman characteristic) remains uninvestigated due to material instability and challenges in capturing weak Raman signals.
• Existing research primarily focuses on intralayer Raman modes, overlooking the temperature sensitivity of interlayer breathing modes.

Purpose of the Study:

• To experimentally determine the first-order temperature coefficient of the breathing modes in multilayer phosphorene.
• To investigate the temperature-dependent phonon scattering mechanisms (three-phonon and four-phonon processes) influencing these breathing modes.
• To explore the anomalous blue shift behavior of phonon modes within a specific temperature range (100-150 K).

Main Methods:

• Capturing Raman scattering spectra of breathing modes in multiple phosphorene flakes across various temperatures.
• Analyzing the spectral shifts to calculate the first-order temperature coefficient.
• Correlating observed phonon scattering phenomena with temperature variations.

Main Results:

• The breathing modes exhibit a negative temperature coefficient of approximately -0.0025 cm^-1/K.
• Three-phonon scattering dominates below ~100 K, transitioning to dominant four-phonon scattering above ~150 K.
• An anomalous blue shift in phonon modes was observed between 100 K and 150 K, attributed to a scattering process transition.

Conclusions:

• Phosphorene's breathing modes are significantly temperature-dependent, impacting interlayer thermal and mechanical properties.
• The identified three- and four-phonon scattering mechanisms highlight phosphorene's substantial interlayer heat transport capability.
• This study provides critical data for modeling phosphorene's thermal behavior and understanding its potential in thermal management applications.