摘要:
目前,虽然In和2N共掺对ZnO最小光学带隙和吸收光谱影响的实验研究均有报道,但是, In和2N共掺在ZnO中均是随机掺杂,没有考虑利用ZnO的单极性结构进行择优取向共掺,第一性原理的出现能够解决该问题.本文采用密度泛函理论框架下的第一性原理平面波超软赝势(GGA+U )方法,计算了纯的ZnO单胞、择优位向高共掺In—2N原子的Zn1?xInxO1?yNy(x=0.0625—0.03125, y =0.0625—0.125)八种超胞模型的态密度分布和吸收光谱分布.计算结果表明,在相同掺杂方式、不同浓度共掺In-2N的条件下,掺杂量越增加,掺杂体系体积越增加、能量越增加,稳定性越下降、形成能越增加、掺杂越难、掺杂体系最小光学带隙越变窄、吸收光谱红移越显著.计算结果与实验结果相一致.在不同掺杂方式、相同浓度共掺In—2N的条件下, In—N沿c轴取向成键共掺与垂直于c轴取向成键共掺体系相比较,沿c轴取向成键共掺体系最小光学带隙越变窄、吸收光谱红移越显著.这对设计和制备新型光催化剂功能材料有一定的理论指导作用.
Abstract:
Nowadays although the In—N co-doping effects on the optical band gap and absorption spectrum of ZnO are studied extensively, all of the In—N co-doped ZnO materials are of random doping, and the preferred orientation doping using the unpolarized structure of ZnO has not been considered so far. Therefore, in this paper, based on the density functional theory using first principles plane-wave ultrasoft pseudopotential (GGA+U ) method, the densities of states and absorption spectra of un-doped and the In—N heavily co-doped Zn1?xInxO1?yNy (x = 0.0625–0.03125, y=0.0625–0.125) in different orientations are calculated. The results show that in the same doping mode, the larger the volume of doping system, the higher the total energy and the formation energy are and the narrower the optical band gap is;the red shifting of absorption spectrum becomes more significant with the increase of In—2N co-doping amount. Those are in good agreement with the experimental results. Under the condition of different doping manners and the same In—2N co-doped concentration, the co-coped In—N atoms along the c-axis orientation, have the narrower optical band gap and more significant red shifting of absorption spectrum than the In—N atoms with the orientation perpendicular to the c-axis. We believe that these results may be helpful for designing and preparing the new photocatalyst materials of In—N heavily co-doped ZnO.
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