Stability of two dimensional (2D) structures based on GaAs

Limited Access
This item is unavailable until:
2017-09-03
Date
2015-08
Editor(s)
Advisor
Gülseren, Oğuz
Supervisor
Co-Advisor
Co-Supervisor
Instructor
Source Title
Print ISSN
Electronic ISSN
Publisher
Bilkent University
Volume
Issue
Pages
Language
English
Journal Title
Journal ISSN
Volume Title
Series
Abstract

Graphene is a two dimensional material isolated for the first time in 2004. After this, two dimensional materials has become an appealing research area for the scientists because of their exotic properties. In search for two dimensional materials, both experimental and theoretical investigations have been carried out. First-principles approaches have been used to predict silicene and germane theoretically. A technologically important semiconductor material is GaAs, however there is no report of two dimensional materials which is based on GaAs. We attempted to find a new stable 2D structure which is formed from either Ga and As atoms based on GaAs or its functionalized form with O atoms. In search for such a system, we performed density functional theory based calculations by using a plane-wave pseudopotential method. We used local density approximation for the exchange correlation potential. First, we performed geometrical optimization calculation in order to identify possible stable structures. We obtained electron band diagrams and phonon dispersion relations to check electronic properties and stability of these materials. We found three structures which are based on GaAs (100), (110) and (110) surfaces. We found that these two dimensional materials are geometrically stable but after performing phonon calculations we observe that there are some negative energy modes. In addition we identified one system which is based on Ga, As, and O atoms. Even though this structure is stable after geometry optimization, it has negative phonon modes in its phonon band diagrams.

Course
Other identifiers
Book Title
Citation
Published Version (Please cite this version)