Abstract Among common methods to form polycrystalline silicon (poly-Si) films for passivating-contact solar cells, physical vapor deposition, in particular sputtering, is the safest one as it does not require any toxic gaseous precursors. One of the critical parameters to control the properties of sputtered silicon films is their deposition pressure. In this work, structural and optoelectronic characteristics of ex-situ boron-doped poly-Si/SiOx passivating contacts, formed from sputtered intrinsic amorphous silicon (a-Si) deposited at different pressures on top of SiOx/c-Si substrates and subjected to a high-temperature boron diffusion step, are investigated. The deposition rate and density of the as-deposited a-Si films increase with reducing pressure. Low-temperature photoluminescence spectra captured from the as-deposited samples at different pressures do not show typical emissions from hydrogenated a-Si. Meanwhile, their Fourier-transform infrared absorption spectra all show Si–H stretching modes, indicating that hydrogen had been initially incorporated into the chemical SiOx layers and eventually hydrogenated the a-Si/SiOx interfaces during the sputtering process. After the high-temperature boron-diffusion step, all hydrogen-related peaks disappear. Lower pressure films (1.5 and 2.5 mTorr) show more consistent improved performance after hydrogen treatments, compared to higher pressure films (4 and 5 mTorr). The resultant passivating contacts at 2.5 mTorr achieve a low single-side recombination current density Jo of ~9 fA/cm2, whereas their contact resistivity is still low at 15 mΩ cm2.

中文翻译：

---

基于溅射硅的异位掺硼多晶Si/SiOx钝化触点的沉积压力相关结构和光电特性

摘要 在形成用于钝化接触太阳能电池的多晶硅 (poly-Si) 薄膜的常用方法中，物理气相沉积，尤其是溅射，是最安全的方法，因为它不需要任何有毒的气态前体。控制溅射硅膜性能的关键参数之一是它们的沉积压力。在这项工作中，异位掺硼多晶硅/SiOx 钝化触点的结构和光电特性，由溅射的本征非晶硅 (a-Si) 在不同压力下沉积在 SiOx/c-Si 衬底顶部形成并经受研究了高温硼扩散步骤。沉积态 a-Si 薄膜的沉积速率和密度随着压力的降低而增加。在不同压力下从沉积样品中捕获的低温光致发光光谱没有显示氢化 a-Si 的典型发射。同时，他们的傅里叶变换红外吸收光谱都显示出 Si-H 伸缩模式，表明氢最初已被掺入化学 SiOx 层中，并最终在溅射过程中氢化了 a-Si/SiOx 界面。在高温硼扩散步骤之后，所有与氢相关的峰都消失了。与高压薄膜（4 和 5 毫托）相比，低压薄膜（1.5 和 2.5 毫托）在氢处理后表现出更一致的改进性能。由此产生的 2.5 mTorr 钝化接触实现了 ~9 fA/cm2 的低单侧复合电流密度 Jo，而它们的接触电阻率仍然很低，仅为 15 mΩ cm2。