Temperature Evolution of Phonon Properties in Few-Layer Black Phosphorus

We present the results of Raman measurements of few-layer black phosphorus in a temperature range between 4 and 400 K. The BP Raman mode positions, widths, and intensity ratios exhibit apparent nonlinear temperature dependences, which we attributed to the phenomenon of optical phonon decay into two or three acoustic phonons. These results pave the way for a deeper understanding of the phonon and thermal properties of black phosphorus.