Abstract Conventional p–n junction solar cells exhibit good thermal stability but poor carrier selectivity. The main aim of this study was to achieve improved passivation along with carrier-selective contact for a solar cell having a tunnel oxide passivated contact (TOPCon) structure. To this end, we attempted to optimize the polysilicon (poly-Si) layer deposited on an ultrathin (~1.3 nm) SiO2 tunnel oxide layer to achieve high carrier lifetime and low recombination. We observed the passivation properties under varied thicknesses of the poly-Si layer and the phosphine (PH3) gas flow rate at three different annealing temperatures. Our experimental approach was able to achieve the best passivation properties by use of a moderately thin poly-Si layer. The poly-Si layer thickness was varied from 55 to 113 nm, and the PH3 flow rate was varied from 10 to 80 sccm at three different annealing temperatures in the range of 800–950 °C. The 113-nm-thick poly-Si layer was able to yield an implied open-circuit voltage (i-VOC) of 733 mV along with a very low recombination current density (J0) of 5.2 fA/cm2 at a PH3 flow rate of 40 sccm and post-deposition annealing temperature of 900 °C. A higher annealing temperature resulted in damage to the substrate, which in turn led to poor passivation; hence, optimization of this temperature was necessary. The passivation properties were further improved via the deposition of a thin (10-nm thick) Al2O3 layer on one side (i.e., front side) of the symmetric cell structure. This deposition caused a decrease in J0 to 2.5 fA/cm2 and an increase in i-VOC to 742 mV. These results are attributed to a decrease in the number of interfacial defects, promoted formation of a carrier collector layer, and good field-effect passivation. We performed a simulation study for the realization of a TOPCon solar cell and employed therein the experimentally determined parameters, which yielded highly promising cell results. Our proposed simple and cost-effective approach has high potential for future large-scale production of high-efficiency TOPCon solar cells.

中文翻译：

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使用薄 Al2O3 层的钝化性能分析和用于实现高效 TOPCon 电池的模拟

摘要 传统的 p-n 结太阳能电池表现出良好的热稳定性，但载流子选择性较差。本研究的主要目的是为具有隧道氧化物钝化接触 (TOPCon) 结构的太阳能电池实现改进的钝化和载流子选择性接触。为此，我们尝试优化沉积在超薄 (~1.3 nm) SiO2 隧道氧化物层上的多晶硅 (poly-Si) 层，以实现高载流子寿命和低复合。我们在三种不同的退火温度下观察了不同厚度的多晶硅层和磷化氢 (PH3) 气体流速下的钝化特性。我们的实验方法能够通过使用适度薄的多晶硅层实现最佳钝化性能。多晶硅层厚度从 55 到 113 nm 不等，PH3 流速在 800-950 °C 范围内的三种不同退火温度下从 10 到 80 sccm 不等。113 nm 厚的多晶硅层能够产生 733 mV 的隐含开路电压 (i-VOC) 以及在 PH3 流速为 5.2 fA/cm2 的非常低的复合电流密度 (J0) 40 sccm 和 900 °C 的沉积后退火温度。较高的退火温度导致基板损坏，进而导致钝化不良；因此，有必要优化该温度。通过在对称电池结构的一侧（即正面）沉积薄（10 纳米厚）的 Al2O3 层，钝化特性得到进一步改善。这种沉积导致 J0 降低至 2.5 fA/cm2，i-VOC 增加至 742 mV。这些结果归因于界面缺陷数量的减少、载流子集电极层的形成以及良好的场效应钝化。我们对 TOPCon 太阳能电池的实现进行了模拟研究，并在其中采用了实验确定的参数，这产生了非常有希望的电池结果。我们提出的简单且具有成本效益的方法对于未来大规模生产高效 TOPCon 太阳能电池具有很大的潜力。