Compensation of Acceptors in ZnO Nanocrystals by Adsorption of Formic Acid
Compensation of Acceptors in ZnO Nanocrystals by Adsorption of Formic Acid
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DOI：
10.1021/jp303835a
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发表时间：
2012-08
影响因子：
3.7
通讯作者：
S. T. Teklemichael;M. McCluskey
中科院分区：
文献类型：
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作者：
S. T. Teklemichael;M. McCluskey
氧化锌（ZnO）纳米晶体在光电器件中具有潜在的应用前景，并被广泛用作各种化学过程的催化剂。利用红外（IR）和光致发光（PL）光谱，我们提供了氧化锌纳米晶体含有氢受体的证据，并提出了一个能级方案来解释这一观察结果。在液氦温度下，与受体电子跃迁相对应的红外吸收峰在暴露于甲酸（HCOOH）蒸气后消失。这一观察结果与甲酸离子对受体的电补偿一致。甲酸离子的能级估计高于价带最大值约0.9 eV。室温红外测量表明，甲酸类物质吸附在ZnO纳米晶体表面。对于暴露于HCOOH的样品，以3.2 eV为中心的宽PL峰归因于与甲酸类结合的激子。
Zinc oxide (ZnO) nanocrystals have potential applications in optoelectronic devices and are widely used as catalysts for a variety of chemical processes. Using infrared (IR) and photoluminescence (PL) spectroscopies, we provide evidence that ZnO nanocrystals contain hydrogenic acceptors and propose an energy-level scheme to explain the observations. IR absorption peaks at liquid-helium temperatures, which correspond to electronic transitions of the acceptor, disappeared after exposure to formic acid (HCOOH) vapor. This observation is consistent with electrical compensation of the acceptor by the formate ion. The energy level of the formate ion is estimated to be ∼0.9 eV above the valence-band maximum. Room temperature IR measurements show that the formate species are adsorbed on the surface of ZnO nanocrystals. A broad PL peak centered at 3.2 eV, for samples exposed to HCOOH, is attributed to an exciton bound to a formate species.