表面悬挂键对GaAs纳米线掺杂的影响及其钝化

利用第一性原理计算方法研究了表面悬挂键对GaAs纳米线掺杂的影响及其钝化．计算结果显示，不论是闪锌矿结构还是纤锌矿结构，GaAs纳米线表面Ga原子上带正电荷的表面悬挂键都是一类稳定的缺陷，并且这种稳定性不会随着纳米线直径的变化而变化．这种表面悬挂键会形成载流子陷阱中心从而从p型掺杂的GaAs纳米线俘获空穴，使得纳米线的掺杂效率下降．和NH3相比，NO2 具有足够的电负性来俘获GaAs纳米线表面悬挂键上的未配对电子，从而有效地钝化GaAs纳米线的表面悬挂键，提高纳米线的p型掺杂效率，并且这种钝化特性不会随着纳米线直径的变化而改变．

Effect of Surface Dangling Bonds and Molecular Passivation on Doped GaAs Nanowires

We have investigated the effect of surface dangling bonds and molecular passivation on the doping of GaAs nanowires by first-principles calculations. Results show that the positively charged surface dangling bond on Ga atom is the most stable defect for both ultrathin and large size GaAs nanowires. It can form the trap centers of holes and then prefer to capture the holes from p-type doping. Thus it could obviously reduce the efficiency of the p-type doping. We also found that the NO2 molecule is electronegative enough to capture the unpaired electrons of surface dangling bonds, which is an ideal passivation material for the Zn-doped GaAs nanowires.