Phonon modes in InAs quantum dots - art. no. 195315

Phonon modes in spherical InAs quantum dots (QDs) with up to 11 855 atoms ( about 8.5 nm in diameter) are calculated by using a valence force field mod el, and all the vibration frequencies and vibration amplitudes of the QDs a re calculated directly from the lattice-dynamic matrix. The projection oper ators of the irreducible representations of the group theory are employed t o reduce the computational intensity, which further allows us to investigat e the quantum confinement effect of phonon modes with different symmetries. It is found that the size effects of phonon modes depend on the symmetry o f the modes. For zinc-blende structure, the modes with A(1) symmetry has th e strongest quantum confinement effect and the T-1 mode the weakest. There could be a crossover of symmetries of the highest frequencies from A(1) to T-2 as the size of the QDs decreases. The behavior of vibration amplitudes and vibration energies of phonon modes in different symmetries are also inv estigated in detail. These results provide microscopic details of the phono n properties of QDs that are important to the fundamental understanding and potential applications of semiconductor QDs.