Post date: Feb 22, 2014 4:39:17 PM
III-V nanowires show great potential for applications ranging from field effect transistors to photo-detectors. One of the interesting things about these systems is that for very small nanowires, the wurtzite crystal phase is preferred over the zinc-blende phase found in bulk crystals. This change in crystal structure could have important implications in terms of band structure, dielectric constant, and phonon properties. However, since the wurtzite phase can not be grown in bulk, it has been difficult to predict the lattice dynamics in this phase. In our work recently published in Physical Review B (PRB, 89, 054302 (2014)), we provide the first ab-initio calculation for the phonon dispersion and Raman spectra for wurtzite InP. We show that including the 4d In electrons as valence electrons is crucial to predict the correct frequencies of the optical branches. We also find that the specific heat and group velocities of wurtzite and zincblende InP are very similar. This means that any difference in the thermal conductivities in these two polytypes should be due to differences in phonon-phonon scattering (a topic of future work!).
Also, congrats to Saikat for his first (of many) publication with the group!
Keywords: Lattice dynamics, Raman, Indium Phospide, Phonon Dispersion, Quantum Espresso