Transition metal oxides are pivotal in enhancing surface passivation and facilitating charge transfer (CT) in silicon based photonic devices, improving their efficacy and affordability through interfacial engineering. This study investigates TiO₂/Si heterojunctions prepared by atomic layer deposition (ALD) with different pre-ALD chemical and post-ALD thermal treatments, exploring their influence on the surface passivation and the correlation with the CT at the TiO₂–Si interface. Surface passivation quality is evaluated by the photoconductance decay method to study the effective carrier lifetime, while CT from Si to TiO₂ is examined by transient reflectance spectroscopy. Surprisingly, the as-deposited TiO₂ on HF-treated n-Si (without interfacial SiO_x) demonstrates superior surface passivation with an effective lifetime of 1.23 ms, twice that of TiO₂/SiO_x/n-Si, and a short characteristic CT time of 200 ps, tenfold faster than that of TiO₂/SiO_x/n-Si. Post-ALD annealing at temperatures approaching the TiO₂ crystallization onset re-introduces the SiO_x layers in HF-treated samples and induces chemical and structural changes in all the samples which decrease passivation and prolong the CT time and are hence detrimental to the photonic device performance.

中文翻译：

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TiO2-Si 界面表面钝化和电荷转移的非接触式分析


过渡金属氧化物对于增强表面钝化和促进硅基光子器件中的电荷转移（CT）至关重要，通过界面工程提高其功效和可承受性。本研究研究了通过原子层沉积（ALD）通过不同的 ALD 前化学处理和 ALD 后热处理制备的 TiO ₂ /Si 异质结，探讨它们对表面钝化的影响以及与 CT 的相关性。 TiO ₂ –Si 界面。通过光电导衰减方法评估表面钝化质量以研究有效载流子寿命，同时通过瞬态反射光谱检查从Si到TiO ₂ 的CT。令人惊讶的是，在 HF 处理的 n-Si（无界面 SiO _x ）上沉积的 TiO ₂ 表现出优异的表面钝化性能，有效寿命为 1.23 ms，是 TiO 的两倍< b5> /SiO _x /n-Si，特征 CT 时间短，为 200 ps，比 TiO ₂ /SiO _x 结晶起始温度的 ALD 后退火会在 HF 处理的样品中重新引入 SiO _x 层，并在所有样品中引起化学和结构变化，从而减少钝化和延长 CT 时间，因此不利于光子器件的性能。