Stabilization of a Ga-adlayer structure with the zincblende stacking sequence in the GaN(0 0 0 -1) surface at the nanoscale.
Profile imaging by in situ high-resolution transmission electron microscopy is used to elucidate reconstructions of the GaN(0 0 0 -1) surface during annealing in the TEM. We have successfully captured a detailed process of a change from the stacking sequence of the wurtzite to that of the zincblende structure in the topmost three Ga layers for the surface with nanoscale hill-and-valley structures. For ab initio calculations of the change in the sequence, a model structure is approximated by the addition of a 1 × 1 Ga layer on the GaN(0 0 0 -1) surface (i.e., 1 × 1 Ga-adlayer structure). The ab initio calculations predict that, as the surface size decreases, the 1 × 1 Ga-adlayer structure with the wurtzite stacking sequence in the topmost three Ga layers becomes destabilized against the adlayer with the zincblende stacking sequence in the surface layers, which well elucidates the experimental observation.
Department of Materials Science and Engineering and Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul 08826, Republic of Korea. bolee@snu.ac.kr.
Sung Bo
http://orcid.org/0000-0002-3482-8610
SB
Lee
Nano-Bio Electron Microscopy Research Group, Korea Basic Science Institute, Daejeon 34133, Republic of Korea.
Seung Jo
SJ
Yoo
Department of Materials Science and Engineering and Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul 08826, Republic of Korea. bolee@snu.ac.kr.
Kunsu
K
Kim
Korea Research Institute of Standards and Science and Department of Nano Science, University of Science and Technology, Daejeon 34113, Republic of Korea. kimyongsung@gmail.com.
Yong-Sung
YS
Kim
Center for Intergreated Nanostructure Physics, Institute for Basic Science (IBS), Suwon 16419, Republic of Korea and Department of Energy Science, Sunkyunkwan University (SKKU), Suwon 16419, Republic of Korea. youngmk@skku.edu.
Young-Min
YM
Kim
Nano-Bio Electron Microscopy Research Group, Korea Basic Science Institute, Daejeon 34133, Republic of Korea.
Jin-Gyu
JG
Kim
Department of Materials Science and Engineering and Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul 08826, Republic of Korea. bolee@snu.ac.kr.
Heung Nam
HN
Han