Spectropic determination of flatband potential and carrier density of ZnO nanowires with/without hydrogen plasma treatment
Spectropic determination of flatband potential and carrier density of ZnO nanowires with/without hydrogen plasma treatment
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有/没有氢等离子体处理的 ZnO 纳米线的平带电势和载流子密度的光谱测定
DOI：
10.1117/12.907500
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Jean-Jacques Delaunay
中科院分区：
文献类型：
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作者：
Miao Zhong;Jean-Jacques Delaunay
采用简单的化学气相沉积方法在蓝宝石衬底上制备了密集的垂直ZnO纳米线阵列。电化学阻抗谱研究了ZnO纳米线的电解液肖特基接触。所合成的ZnO纳米线具有n型半导体性质，在Ag/AgCl电极上的平带电位约为0 V（0.05 V）。0 V平带电位是ZnO/电解质界面肖特基接触引起的费米能级差和ZnO纳米线表面氧空位引起的表面吸附效应的平衡结果。氢等离子体处理进行钝化的ZnO纳米线中的氧空位。相同的ZnO纳米线阵列样品经氢等离子体处理后，其平带电位明显漂移至-0.6V左右。负的平带电位，表明在ZnO纳米线的表面的电子耗尽区，观察到由于n型ZnO纳米线和电解质之间的费米能级差，没有强烈的影响的氧空位相关的表面吸附效应。此外，在ZnO纳米线的载流子密度增加了近四个数量级后，氢等离子体处理。载流子密度的增加证实了现有的报道，氢原子占据间隙位置的ZnO纳米线，除了在氢等离子体处理后的氧空位。
A dense array of vertical ZnO nanowires on a-plane sapphire substrate was synthesized by a simple chemical vapor deposition method. The electrolyte-based Schottky contact of the ZnO nanowires was investigated by electrochemical impedance spectroscopy. An n-type semiconductor behavior and a flat-band potential of about 0 V (0.05 V) versus Ag/AgCl electrode were obtained for the synthesized ZnO nanowires. The ~ 0 V flat-band potential is suggested to be a balanced result of (1) the Femi-level difference induced by the Schottky contact at the ZnO/electrolyte interface and (2) the oxygen vacancy induced surface adsorption effect at the ZnO nanowire surface. Hydrogen plasma treatment was carried out to passivate the oxygen vacancies in the ZnO nanowires. An obvious shift of the flat-band potential to about - 0.6 V was obtained for the same ZnO nanowire array sample after the hydrogen plasma treatment. The negative flatband potential, indicating an electron depletion region at the surface of ZnO nanowires, is observed owing to the Fermilevel difference between the n-type ZnO nanowires and the electrolyte, without a strong influence of the oxygen vacancy-related surface adsorption effect. Moreover, the carrier density in the ZnO nanowires was increased by almost four orders of magnitude after the hydrogen plasma treatment. The increase in carrier density confirms existing reports of hydrogen atoms occupying interstitial sites in the ZnO nanowires in addition to the oxygen vacancies after the hydrogen plasma treatment.