Polycrystalline silicon on silicon oxide (poly-Si/SiOx) passivating contacts enable ultrahigh-efficiency interdigitated back contact silicon solar cells. To prevent shunt between n- and p-type-doped fingers, an insulating region is required between them. We evaluate the use of intrinsic poly-Si for this isolation region. Interdigitated fingers were formed by plasma deposition of doped hydrogenated amorphous silicon through mechanically aligned shadow masks on top of a full-area intrinsic hydrogenated amorphous silicon (a-Si:H) layer. High-temperature annealing then crystallized the a-Si:H to poly-Si and drove in the dopants. Two mechanisms were identified which cause contamination of the intrinsic poly-Si gap during processing. During deposition of doped fingers, we show using secondary ion mass spectrometry and conductivity measurements that the intrinsic gap becomes contaminated by doped a-Si:H tails several nanometers thick to concentrations of ~1020 cm-3. Another source of contamination occurs during high-temperature annealing, where dopants desorb from doped regions and readsorb onto intrinsic a-Si:H. Both pathways reduce the resistivity of the intrinsic gap from ~105 to ~10-1 Ω·cm. We show that plasma etching of the a-Si:H surface before crystallizing with a capping layer can eliminate the contamination of the intrinsic poly-Si, maintaining a resistivity of ~105 Ω·cm. This demonstrates masked plasma deposition as a dopant patterning method for Si solar cells.

中文翻译：

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在钝化叉指背接触硅太阳能电池中用本征多晶硅隔离 p 和 n 掺杂指状物


氧化硅上的多晶硅 (poly-Si/SiOx) 钝化触点可实现超高效率叉指背接触硅太阳能电池。为了防止 n 型和 p 型掺杂指之间的分流，它们之间需要一个绝缘区域。我们评估了本征多晶硅在该隔离区域的使用。通过在全面积本征氢化非晶硅 (a-Si:H) 层顶部机械对准的荫罩，通过掺杂氢化非晶硅的等离子体沉积形成叉指状指状物。然后进行高温退火，使 a-Si:H 结晶为多晶硅，并引入掺杂剂。确定了在加工过程中导致本征多晶硅间隙污染的两种机制。在掺杂指状物的沉积过程中，我们使用二次离子质谱和电导率测量表明，本征间隙被几纳米厚的掺杂 a-Si:H 尾部污染，浓度约为 1020 cm-3。另一个污染源发生在高温退火过程中，其中掺杂剂从掺杂区域解吸并重新吸附到本征 a-Si:H 上。两种途径都将固有间隙的电阻率从~105 Ω·cm 降低到~10-1 Ω·cm。我们表明，在用覆盖层结晶之前对 a-Si:H 表面进行等离子蚀刻可以消除本征多晶硅的污染，保持约 105 Ω·cm 的电阻率。这证明了掩模等离子体沉积作为硅太阳能电池的掺杂剂图案化方法。