Theoretical Study About STO Films’ Growth On Faulty Surfaces Of GaN(0001)

The Ga N material contains various surface defects:vacancy defects 、line defects and steps defects. These defects induce the growth of Ferroelectric thin films which grow on it. Ti O2 molecule, Sr O molecule and Ba O molecule are constructed on these defects. Using the first principles calculation software – MS software design and optimize each model.The total energy, density of states, electron density and adsorption energy are also gained.Firstly, the most easily formation of point defects is VGa defect. We placed Ti O2 molecule, Sr O molecule and Ba O molecule on VGa defect surface in different positions.The result shows: the adsorption of Ti O2 molecule on VGa point defect surface is weaker than it is on a clean surface. In the same condition, we calculate the adsorption of Sr O molecule and Ba O molecule on VGa defect. Result shows that, the adsorption of Sr O molecular or Ba O molecule are easily adsorbed on VGa defect surface than Ti O2 molecule. While clean surface adsorption of Ti O2 molecule is easier than the adsorption of the rest two kinds of molecules. Point defect VGa adsorption of Sr O molecule or Ba O molecule result shows that Sr-O key and Ba-O key after adsorption are all along the direction of [11-20] direction. These are in good agreement with experimental data.Secondly, the Ga-terminated Ga N(0001) surfaces contains different line defects.We constructed typical line defects: [11-20] line and [10-10] line. The result shows that the [11-20] line absorption of Ti O2 molecule is weaker than that adsorption on[10-10] line defect.Finally, we bulid different step defects on the Ga-terminated Ga N(0001) surfaces.The result shows that the [11-20] step defects absorption of Ti O2 molecule is stronger than the adsorption on [10-10] step defect. The optimal adsorption style of Ti O2 molecule shows that O-O key after adsorption are along the direction of [11-20]direction. These are in good agreement with experiments.