Synchrotron photoemission analysis of semiconductor/electrolyte interfaces by the frozen-electrolyte approach: interaction of HCl in 2-propanol with GaAs(100).
Synchrotron photoemission analysis of semiconductor/electrolyte interfaces by the frozen-electrolyte approach: interaction of HCl in 2-propanol with GaAs(100).
复制标题
通过冷冻电解质方法对半导体/电解质界面进行同步光发射分析：2-丙醇中的 HCl 与 GaAs(100) 的相互作用。
DOI：
10.1021/jp056375u
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
W. Jaegermann
中科院分区：
文献类型：
--
作者：
T. Mayer;M. Lebedev;R. Hunger;W. Jaegermann
探索了超高真空条件下固/液界面化学过程同步加速器光电发射光谱分析新方法的前景。在 N2 气氛下蚀刻掉自然氧化层后，将衬底冷却至液氮温度，将 HCl-2-丙醇溶液薄层冻结在半导体 GaAs(100) 晶片表面上。通过暴露于同步加速器辐射（SR）和逐步加热原位诱导的化学反应已被监测。蚀刻和冷冻后，表面立即被附着有 1、2、3 和 4 个 Cl 离子并与 As 原子晶格背键合的氯化镓以及元素砷 As0 和 2-丙醇覆盖。在低温下暴露于 SR 会产生表面 As 氯化物，但会损失 As0。 GaCl3 和 GaCl2 排放量减少，而 GaCl 排放量增加。另一方面，将样品加热到大约 130 K，刚好高于 H2O 解吸，会导致 AsCl3 与底物 GaAs 发生热力学预期反应，形成 Ga 氯化物物质和 AsO。将样品加热至室温，表面仅留下 As0，而对于镓来说，所有表面氯化物的含量均大幅降低。进一步加热至 400 K，元素砷开始解吸，氯化镓表面含量减少。使用不同的激发能量，对反应产物的深度组成进行了监测，表明在反应的每个阶段，向原始底物减少氯化数和增加Ga与As氯化物含量的趋势。
Perspectives of a new approach for the synchrotron photoemission spectroscopic analysis of chemical processes at solid/liquid interfaces under UHV conditions have been explored. A thin layer of HCl-2-propanol solution was frozen-in on the semiconductor GaAs(100) wafer surface by cooling the substrate to liquid nitrogen temperature after etching off the native oxide layer under N2 atmosphere. Chemical reactions induced in situ by exposure to synchrotron radiation (SR) and by stepwise heating have been monitored. Right after etching and freezing, the surface is covered by gallium chlorides with 1, 2, 3, and 4 Cl ions attached and lattice back-bonded to As atoms, as well as by elemental arsenic As0 and 2-propanol. Exposure to SR at low temperature produces surface As chlorides at the expense of As0. The GaCl3 and GaCl2 emissions diminish while GaCl is enhanced. On the other hand, heating the sample to approximately 130 K just above H2O desorption causes the thermodynamically expected reaction of AsCl3 with the substrate GaAs to form Ga chloride species and As0. Heating the sample to room temperature leaves only As0 on the surface and for gallium the content of all surface chlorides is drastically reduced. By further heating to 400 K elemental arsenic starts to desorb and the Ga chloride surface content is reduced. Using different excitation energies the depth composition of the reaction products has been monitored indicating a tendency of decreasing chlorination numbers and increasing Ga vs As chloride content toward the pristine substrate at each stage of the reaction.