The influence of chemisorption on the defect equilibrium of metal oxide thin films
The influence of chemisorption on the defect equilibrium of metal oxide thin films
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DOI：
10.1063/1.362936
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发表时间：
1996-08-01
影响因子：
3.2
通讯作者：
Geistlinger, H
中科院分区：
文献类型：
--
作者：
Geistlinger, H
利用金属氧化物（MOs）本征点缺陷的精确电荷密度，将Volkenstein提出的化学吸附的现象学电子理论应用于整个xi区域(xi=D/L（D)， D为薄膜厚度，L(D)为德拜长度）的MO薄膜上的类受体和类给体化学吸附。基于肖特基缺陷模型、电子平衡的Volkenstein模型和完全平衡的综合模型，讨论了多晶ZnO薄膜平均电子浓度[n]（p(O2)，T）与e(-EA/kT)p(O2)（-m(T)）成比例的实验温度和氧分压依赖关系。事实证明，使用单晶质量作用常数的肖特基缺陷模型不会产生实验高温极限（T=1000 K: E(a)=1.6 eV, m=0.26）。这一极限是利用多晶薄膜中较高的氧空位平均浓度（由于晶界的存在）获得的。电子平衡和完全平衡的比较表明，在考虑的温度范围内，通过移动的带正电的氧空位筛选表面电荷具有约30%的表面电位的巨大降低作用。(C) 1996年美国物理研究所。
Using the exact charge density of intrinsic point defects of metal oxides (MOs), the phenomenological electron theory of chemisorption, developed by Volkenstein, is applied to acceptorlike and donorlike chemisorption on MO thin films for the whole xi region (where xi=D/L(D), D is the film thickness, and L(D) is Debye length). The experimental temperature and oxygen partial pressure dependence of the averaged electron concentration [n](p(O2),T) proportional to e(-EA/kT)p(O2)(-m(T)) for polycrystalline ZnO films are discussed on the bases of three different models: the Schottky-defect model, the Volkenstein model for electronic equilibrium, and the comprehensive model for complete equilibrium. It turns out that a Schottky-defect model that uses single-crystal-mass action constants will not yield the experimental high temperature limit (T=1000 K: E(A)=1.6 eV, m=0.26). This limit is obtained using a higher averaged concentration of oxygen vacancies for polycrystalline films (due to the presence of grain boundaries). The comparison between the electronic and complete equilibrium shows that the screening of the surface charge through mobile positively charged oxygen vacancies has a tremendous reducing effect of about 30% of the surface potential in the temperature range considered. (C) 1996 American Institute of Physics.