Numerical Analysis on Phonon Localization of Vacancy Type Disordered Graphene

作者：Islam Md Sherajul; Rahaman Md Tawabur; Bhuiyan Ashraful Ghani; Hashimoto Akihiro^*

来源：Journal of Circuits, Systems, and Computers, 2015, 24(2): 1540002.

DOI：10.1142/S0218126615400022

• Vibrational properties
• graphene
• vacancy defects
• phonon density of states
• hydrogen passivation

The phonon properties of hydrogen passivated graphene with vacancy defects are studied using the forced vibrational method. The phonon density of states (PDOSs), typical mode patterns and localization length are calculated over a broad range of vacancies. We find that phonon properties of graphene strongly depend on the system size. We observe a broadening and softening of the PDOS peaks with the increase of vacancy concentrations. We find an increasing C-H stretching mode with the increase of defect density. Our numerical experiments reveal that the typical mode pattern for the K point in-plane TO (iTO) modes phonon show the spatial localized vibrations persuaded by vacancies, which are in conceptually good agreement with the large D band peak of the Raman spectra comes from the imperfections of crystal. For the K point iTO mode phonons, a typical localization length is on the order approximate to 5 nm for vacancy-type defects at high concentrations of 30% is observed. The localization effects manifest themselves in the projected temperature behavior of the constant-volume specific heat capacity of pristine and disordered graphene samples.

• 出版日期2015-2