Electronic Band Structures and Native Point Defects of Ultrafine ZnO Nanocrystals.
Ultrafine ZnO nanocrystals with a thickness down to 0.25 nm are grown by a metalorganic chemical vapor deposition method. Electronic band structures and native point defects of ZnO nanocrystals are studied by a combination of scanning tunneling microscopy/spectroscopy and first-principles density functional theory calculations. Below a critical thickness of ∼1 nm ZnO adopts a graphitic-like structure and exhibits a wide band gap similar to its wurtzite counterpart. The hexagonal wurtzite structure, with a well-developed band gap evident from scanning tunneling spectroscopy, is established for a thickness starting from ∼1.4 nm. With further increase of the thickness to 2 nm, VO-VZn defect pairs are easily produced in ZnO nanocrystals due to the self-compensation effect in highly doped semiconductors.
†Shenzhen Key Laboratory of Laser Engineering, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, P. R. China.|‡Solid State Physics and Magnetism Section, KU Leuven, Celestijnenlaan 200 D, BE-3001 Leuven, Belgium.
Yu-Jia
YJ
Zeng
‡Solid State Physics and Magnetism Section, KU Leuven, Celestijnenlaan 200 D, BE-3001 Leuven, Belgium.
Koen
K
Schouteden
Mozhgan N
MN
Amini
†Shenzhen Key Laboratory of Laser Engineering, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, P. R. China.
Shuang-Chen
SC
Ruan
§State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China.
Yang-Fan
YF
Lu
§State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China.
Zhi-Zhen
ZZ
Ye
Bart
B
Partoens
Dirk
D
Lamoen
‡Solid State Physics and Magnetism Section, KU Leuven, Celestijnenlaan 200 D, BE-3001 Leuven, Belgium.
Chris
C
Van Haesendonck
DFT calculations; defects; nanocrystals; scanning tunneling spectroscopy; zinc oxide