Black silicon (b-Si) surfaces typically have a high density of extreme nanofeatures and a significantly large surface area. This makes high-quality surface passivation even more critical for devices such as solar cells with b-Si surfaces. It has been hypothesized that conformal dielectrics with a high fixed charge density ( ${{\boldsymbol{Q}}_{\boldsymbol{f}}}$ ) are preferred as the nanoscale features of b-Si result in a significant enhancement of field-effect passivation. This article uses 1-D, 2-D, and 3-D numerical simulations to study surface passivation of b-Si, where we particularly focus on the charge carrier control by | ${{\boldsymbol{Q}}_{\boldsymbol{f}}}$ | up to 1 × 10 ¹³ cm ⁻² under accumulation conditions. We will show that there is a significant space charge region compression in b-Si nanofeatures, which affects the charge carrier population control for moderate | ${{\boldsymbol{Q}}_{\boldsymbol{f}}}$ | up to ≈1 × 10 ¹² cm ⁻² . The average surface minority charge carrier density can be reduced by 70% in some cases, resulting in an equivalent reduction in area-normalized surface recombination losses if the effective surface recombination velocity ( ${{\boldsymbol{S}}_{{\rm{eff}}}}$ ) is limited by minority carriers. This provides a possible solution for the empirical ${{\boldsymbol{S}}_{{\rm{eff}}}} \propto 1/{\boldsymbol{Q}}_{\boldsymbol{f}}^4$ reported previously. We will also show that the situation is more complicated for surface passivation films where the ratio between the electron and hole capture cross section ( ${{\boldsymbol{\sigma }}_{\boldsymbol{n}}}$ / ${{\boldsymbol{\sigma }}_{\boldsymbol{p}}}$ ) is higher than 10 for p -type surfaces. For commonly used surface passivation films with a | ${{\boldsymbol{Q}}_{\boldsymbol{f}}}$ | larger than ≈1 × 10 ¹² cm ⁻² , there is little space charge compression for b-Si. Consequently, ${{\boldsymbol{S}}_{{\rm{eff}}}}$ simply scales with the surface area, i.e., there is no enhanced reduction of surface recombination by field-effect passivation on b-Si.

中文翻译：

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未扩散的黑硅表面的场效应钝化

黑硅 (b-Si) 表面通常具有高密度的极端纳米特征和非常大的表面积。这使得高质量的表面钝化对于具有 b-Si 表面的太阳能电池等设备变得更加重要。已经假设具有高固定电荷密度的共形电介质（ ${{\boldsymbol{Q}}_{\boldsymbol{f}}}$ ) 是首选，因为 b-Si 的纳米级特征导致场效应钝化的显着增强。本文使用 1-D、2-D 和 3-D 数值模拟来研究 b-Si 的表面钝化，其中我们特别关注电荷载流子控制 ${{\boldsymbol{Q}}_{\boldsymbol{f}}}$ | 在积累条件下可达 1 × 10 ¹³ cm ^-2。我们将证明 b-Si 纳米特征中存在显着的空间电荷区压缩，这会影响中等 | 的电荷载流子数量控制。 ${{\boldsymbol{Q}}_{\boldsymbol{f}}}$ | 高达≈1 × 10 ¹² cm ^-2 。在某些情况下，平均表面少数电荷载流子密度可以降低 70%，如果有效表面复合速度（ ${{\boldsymbol{S}}_{{\rm{eff}}}}$ ) 受少数载流子限制。这为经验主义提供了一种可能的解决方案${{\boldsymbol{S}}_{{\rm{eff}}}} \propto 1/{\boldsymbol{Q}}_{\boldsymbol{f}}^4$之前报道过。我们还将表明，表面钝化膜的情况更加复杂，其中电子和空穴捕获截面之间的比率（ ${{\boldsymbol{\sigma }}_{\boldsymbol{n}}}$ / ${{\boldsymbol{\sigma }}_{\boldsymbol{p}}}$ ) 高于 10 磷 型表面。对于常用的表面钝化膜，带有| ${{\boldsymbol{Q}}_{\boldsymbol{f}}}$ | 大于≈1 × 10 ¹² cm ^-2 ，b-Si 几乎没有空间电荷压缩。最后，${{\boldsymbol{S}}_{{\rm{eff}}}}$ 简单地与表面积成比例，即，b-Si 上的场效应钝化没有增强减少表面复合。