Seminarium "Modeling of Complex Systems"

Two-dimensional (2D) materials offer novel physics and potential use in multiple applications. However, many of the layered materials are very sensitive to the local environment and ambient conditions. Black phosphorus (BP) represents an extreme example of sensitivity to moisture and oxygen, which can lead to catastrophic degradation on a time scale of only minutes. Recent studies have shown that encapsulation with hexagonal boron nitride (hBN) protects BP from structural and chemical degradation, while improving its electrical properties making hBN the most commonly used material for encapsulation. In this talk I will examine the influence of hBN encapsulation on the structural and vibrational properties of BP using density functional theory (DFT). I will show that encapsulation strains the BP layer, which has significant impact on the vibrational properties. Both non-encapsulated and encapsulated BP layers, exhibit anomalous evolution of phonon frequencies, which show a redshift with increasing number of layers. The presented theoretical predictions are in good agreement with the results of Raman spectroscopy performed on h-BN encapsulated BP layers.