III–V semiconductors, such as InAs, with an ultrathin high-κ oxide layer have attracted a lot of interests in recent years as potential next-generation metal–oxide–semiconductor field-effect transistors, with increased speed and reduced power consumption. The deposition of the high-κ oxides is nowadays based on atomic layer deposition (ALD), which guarantees atomic precision and control over the dimensions. However, the chemistry and the reaction mechanism involved are still partially unknown. This study reports a detailed time-resolved analysis of the ALD of high-κ hafnium oxide (HfO_x) on InAs(100). We use ambient pressure X-ray photoemission spectroscopy and monitor the surface chemistry during the first ALD half-cycle, i.e., during the deposition of the metalorganic precursor. The removal of In and As native oxides, the adsorption of the Hf-containing precursor molecule, and the formation of HfO_x are investigated simultaneously and quantitatively. In particular, we find that the generally used ligand exchange model has to be extended to a two-step model to properly describe the first half-cycle in ALD, which is crucial for the whole process. The observed reactions lead to a complete removal of the native oxide and the formation of a full monolayer of HfO_x already during the first ALD half-cycle, with an interface consisting of In–O bonds. We demonstrate that a sufficiently long duration of the first half-cycle is essential for obtaining a high-quality InAs/HfO₂ interface.

中文翻译：

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氧化In在InAs上的原子层沉积：时间分辨原位研究的真知灼见

近年来，具有潜在的下一代金属氧化物半导体场效应晶体管，速度更快，功耗更低的III-V半导体（例如InAs）具有超薄的高k氧化物层，引起了人们的广泛兴趣。如今，高κ氧化物的沉积是基于原子层沉积（ALD），它可以保证原子精度并控制尺寸。然而，所涉及的化学和反应机理仍是部分未知的。这项研究报告了高κ氧化oxide（HfO _x）在InAs（100）上。我们使用环境压力X射线光发射光谱法，并在第一个ALD半周期内（即在金属有机前体的沉积过程中）监测表面化学。同时和定量研究了In和As天然氧化物的去除，含Hf的前体分子的吸附以及HfO _x的形成。特别是，我们发现通常使用的配体交换模型必须扩展为两步模型，以正确描述ALD的前半周期，这对于整个过程至关重要。观察到的反应导致天然氧化物的完全去除并形成完整的HfO _x单层已经在第一个ALD半周期内，其界面由In-O键组成。我们证明了足够长的前半个周期的持续时间对于获得高质量的InAs / HfO ₂界面至关重要。