Microstructural and compositional characteristics of GaN films grown on a ZnO-buffered Si (111) wafer.
Polycrystalline GaN thin films have been deposited epitaxially on a ZnO-buffered (111)-oriented Si substrate by molecular beam epitaxy. The microstructural and compositional characteristics of the films were studied by analytical transmission electron microscopy (TEM). A SiO(2) amorphous layer about 3.5 nm in thickness between the Si/ZnO interface has been identified by means of spatially resolved electron energy loss spectroscopy. Cross-sectional and plan-view TEM investigations reveal (GaN/ZnO/SiO(2)/Si) layers exhibiting definite a crystallographic relationship: [111](Si)//[111](ZnO)//[0001](GaN) along the epitaxy direction. GaN films are polycrystalline with nanoscale grains ( approximately 100 nm in size) grown along [0001] direction with about 20 degrees between the (1l00) planes of adjacent grains. A three-dimensional growth mode for the buffer layer and the film is proposed to explain the formation of the as-grown polycrystalline GaN films and the functionality of the buffer layer.
Luo
X H
XH
Electron Microscopy Laboratory and State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China.
Wang
R M
RM
Zhang
X P
XP
Zhang
H Z
HZ
Yu
D P
DP
Luo
M C
MC