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利用第一性原理的方法研究了在ZnO非极性表面和极性表面的不同原子层中,分别用Li原子去替位Zn原予(记为Li_(zn))后的相对稳定性和热离化能.计算结果表明Li_(zn)处于ZnO表面区域时的稳定性优于在ZnO体中时的稳定性,并且Li_(zn)在表面区域的热离化能要比它在体结构中的热离化能大很多,于是,ZnO表面效应的存在会使Li掺杂的ZnO薄膜材料的p型导电能力大幅度降低.这个结果对低维ZnO体系p型掺杂有着重要的指导意义.我们进一步发现,在不同的ZnO表面区域里Li_(zn)的热离化能会表现出很大的差异是源于不同的表面具有不同的静电势分布.
The first-principle method was used to study the relative stability and heat loss of Li atoms in the different atomic layers on the nonpolar ZnO surface and the polar surface, respectively. The results show that the stability of Li_ (zn) in the ZnO surface area is better than that in the ZnO substrate, and the thermal ionization energy of Li_ (zn) in the surface area is better than that in the bulk structure Of the thermal ionization energy is much larger, so the presence of ZnO surface effect will make the p-type conductivity of Li-doped ZnO thin film material greatly reduced the ability of this result for low-dimensional ZnO p-type doping system has an important guiding significance. We further find that the thermal ionization of Li_ (zn) in different ZnO surface regions shows a large difference due to the different electrostatic potential distributions on different surfaces.