SrO分子在GaN(0001)表面吸附的密度泛函理论研究

Theoretical research of SrO adsorption on GaN (0001) surface

建立了SrO/GaN（0001）2×2表面吸附模型,采用基于第一性原理的密度泛函理论平面波超软赝势方法对SrO分子的吸附生长进行了计算,详细研究了SrO分子在表面的吸附位置、吸附能及表面化学键特性。计算发现,SrO分子在GaN（0001）表面吸附不会发生分解,最稳定吸附位为Ga桥位,吸附能达到7.257～7.264 eV。通过电荷布居数和态密度分析,SrO分子吸附后O与表面的一个Ga原子形成的化学键表现出共价键特征,电子由SrO转移给表面部分Ga原子,GaN（0001）仍存在表面态。

The adsorption of SrO on GaN（0001） 2 × 2 surface was theoretically calculated employing the density functional theory within a plane-wave ultrasoft pseudopotential scheme.The adsorption orientation,the adsorption energy,and the bonding characteristics of SrO molecule were studied.The simulated results showed that SrO adsorbs on GaN（0001） surface mainly in the form of undissociated molecule and the most stable position of SrO on surface was at the bridge site of Ga,and the chemical bonding energy was achieved to be 7.257-7.264 eV.The charge population and PDOS reveal that the chemical bonding of Ga—O shows a covalent bonding property.After adsorption,electrons of SrO transfer to part Ga atoms of the GaN（0001） surface,and the surface exists still the surface state.