Impurity vibration modes in II–VI and III–V mixed semiconductors

The analysis of vibration frequencies in dilute semiconducting alloys is addressed, as part of a more vast paradigm for the description of lattice dynamics in semiconductor alloys within the "1 bond ― 2 mode" concept. Specific cases considered are those of Be impurities in ZnSe (system with high elastic contrast; aspects of impurity clustering) and of (Ga,In)As alloys, exhibiting much smaller elastic contrast and almost vanishing value of the mode splitting parameter, Δ. First-principles calculations of frequencies are done by SIESTA method, using 64-atom supercells.