We investigate the silicon surface passivation property of Plasma Atomic Layer Deposited (PALD) hafnium oxide thin films and study its dependence on silicon (Si) doping type, film thickness, and post-deposition annealing conditions. Our results demonstrate that as-deposited HfO_x films exhibit poor passivation quality that can be improved by performing post-deposition annealing at 450 °C in hydrogen ambient. We demonstrate that the films can effectively passivate p-Si surfaces as compared to n-Si, where the surface passivation quality of the films improves with increasing film thickness for both silicon doping types. The best performance with a minority carrier lifetime of 1.7 ms, corresponding surface recombination velocity (SRV) ∼10 cm s⁻¹, is achieved for HfO_x films thickness ∼23 nm deposited on the p-Si substrate. The Capacitance-Voltage (C–V) measurements give an insight into the passivation mechanism of the studied films. Field effect passivation is found to be an important passivation mechanism in PALD-deposited HfO_x films, as revealed by C–V measurements. The films are also characterized using Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS), which reveals the chemical passivation provided by hydrogen ambient annealing. Overall, the impact of hafnium oxide film thickness and hydrogen ambient annealing conditions on silicon surface passivation is investigated. Our findings will help in utilizing plasma ALD process based HfO_x films for silicon solar cell device application.

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薄膜厚度和氢气退火对等离子ALD基氧化铪薄膜钝化性能的影响

我们研究了等离子体原子层沉积 (PALD) 氧化铪薄膜的硅表面钝化特性，并研究了其对硅 (Si) 掺杂类型、薄膜厚度和沉积后退火条件的依赖性。我们的结果表明，沉积态 HfO _x薄膜的钝化质量较差，但可以通过在氢气环境中 450 °C 下进行沉积后退火来改善钝化质量。我们证明，与 n-Si 相比，这些薄膜可以有效地钝化 p-Si 表面，其中两种硅掺杂类型的薄膜的表面钝化质量随着薄膜厚度的增加而提高。沉积在 p-Si 衬底上的HfO _x薄膜厚度约为 23 nm ，获得了最佳性能，少数载流子寿命为 1.7 ms，相应的表面复合速度 (SRV) ∼10 cm s ^-1 。电容-电压 (C–V) 测量可让您深入了解所研究薄膜的钝化机制。C-V 测量表明，场效应钝化是 PALD 沉积 HfO _x薄膜的重要钝化机制。还使用傅里叶变换红外光谱 (FTIR) 和 X 射线光电子能谱 (XPS) 对薄膜进行了表征，揭示了氢气环境退火提供的化学钝化。总体而言，研究了氧化铪膜厚度和氢气氛退火条件对硅表面钝化的影响。我们的研究结果将有助于利用基于等离子 ALD 工艺的 HfO _x薄膜用于硅太阳能电池器件应用。