In this article, we explore magnesium oxide (MgO) as electron-selective contact layer in silicon heterojunction solar cells. We report on the successful deposition of MgO layers by atomic layer deposition at low temperatures ≤200 °C using bis(ethylcyclopentadienyl)magnesium (Mg(CpEt)2) and H2O as precursors. Depositions were carried out on bare crystalline silicon (c-Si) wafers and c-Si wafers with an intrinsic amorphous hydrogenated silicon (i-aSi:H) passivation layer. The resulting interfacial properties, surface passivation quality, and contact resistivity were investigated. Upon initial deposition of MgO on an i-aSi:H/c-Si stack, the c-Si surface passivation degrades drastically. However, with an additional annealing step of 5 min at 200–250 °C, it is possible to reverse the degradation and even to achieve charge carrier lifetimes in excess of those achieved with an i-aSi:H alone. Furthermore, we show that MgO forms an ohmic contact with both MgO/i-aSi:H/c-Si and MgO/c-Si stacks, and we demonstrate solar cells using both types of stacks as electron contact layers.

中文翻译：

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低温原子层沉积氧化镁作为 c-Si 基太阳能电池的钝化电子触点

在本文中，我们探索氧化镁 (MgO) 作为硅异质结太阳能电池中的电子选择性接触层。我们报告了使用双（乙基环戊二烯基）镁（Mg（CpEt）2）和 H2O 作为前驱体，在≤200°C 的低温下通过原子层沉积成功沉积 MgO 层。在裸晶硅 (c-Si) 晶片和具有本征非晶氢化硅 (i-aSi:H) 钝化层的 c-Si 晶片上进行沉积。研究了所得的界面特性、表面钝化质量和接触电阻率。在 i-aSi:H/c-Si 叠层上初始沉积 MgO 后，c-Si 表面钝化急剧下降。然而，在 200–250 °C 下进行 5 分钟的额外退火步骤，有可能逆转退化，甚至实现超过单独使用 i-aSi:H 实现的电荷载流子寿命。此外，我们展示了 MgO 与 MgO/i-aSi:H/c-Si 和 MgO/c-Si 堆叠形成欧姆接触，并且我们展示了使用两种类型的堆叠作为电子接触层的太阳能电池。