Surface structure and diffusion of Si and C adatoms on bare SiC(0001) and SiC(0001) surfaces- density functional theory studies
|Jakub Sołtys 1, Stanisław Krukowski 1,2, Jacek Piechota 1, Jolanta Borysiuk 3|
1. University of Warsaw, Interdisciplinary Centre for Mathematical and Computational Modelling (ICM), Pawinskiego 5a, Warsaw 02-106, Poland
Silicon carbide structures have extremely attractive properties for many applications in electronics. Thus detailed understanding of various stage growth process of SiC structures is of great importance. Density functional theory based ab initio calculations were used to obtain silicon and carbon adatoms energy landscape on both principal polar surfaces of silicon carbide: SiC(0001) and SiC(0001). From these data the adsorption sites, the diffusion paths and energy barriers for the jumps between these minima were determined. The obtained data allowed to describe energy characteristics for the motion of silicon and carbon adatoms on both Si- and C-terminated sides. The energy characteristics include the desorption energy of the adatoms from both surfaces. These data allows to obtain the diffusion length of these species in function of the temperature. In addition the DFT results shows the barrierless conversion of the topmost layer of C-terminated SiC(000) surface to sp2-bonded configuration, that provides a nucleation center for creation of nanopipes, during growth of silicon carbide crystals by modified Lely method in carbon-rich environment. Thus molecular mechanism of nucleation of nanopipes is elucidated. The proposed mechanism also provides explanation of the early stages of growth of graphene layers on C-terminated surfaces of annealed SiC crystals. These hypothesis is supplemented by the transmission electron microscopy images of graphene layers on C-side SiC surfaces.
This work has been supported by Polish Ministry of Science and Higher Education within the SiCMAT Project financed under the European Founds for Regional Development (Contract No. UDAPOIG. 01.03.01-14-155/09).
Presentation: Oral at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, General Session 9, by Jakub Sołtys
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17
Submitted: 2013-04-23 22:01 Revised: 2013-08-01 05:10