Abstract Highly doped GeSn material is interesting for both electronic and optical applications. GeSn:B is a candidate for source-drain material in future Ge pMOS device because Sn adds compressive strain with respect to pure Ge, and therefore can boost the Ge channel performances. A high B concentration is required to obtain low contact resistivity between the source-drain material and the metal contact. To achieve high performance, it is therefore highly desirable to maximize both the Sn content and the B concentration. However, it has been shown than CVD-grown GeSn:B shows a trade-off between the Sn incorporation and the B concentration (increasing B doping reduces Sn incorporation). Furthermore, the highest B concentration of CVD-grown GeSn:B process reported in the literature has been limited to below 1 × 10 20 cm −3 . Here, we demonstrate a CVD process where B δ-doping layers are inserted in the GeSn layer. We studied the influence of the thickness between each δ-doping layers and the δ-doping layers process conditions on the crystalline quality and the doping density of the GeSn:B layers. For the same Sn content, the δ-doping process results in a 4-times higher B doping than the co-flow process. In addition, a B doping concentration of 2 × 10 21 cm −3 with an active concentration of 5 × 10 20 cm −3 is achieved.

中文翻译：

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使用 B δ 掺杂层在 CVD 生长的 GeSn:B 中增强 B 掺杂

摘要 高掺杂 GeSn 材料对电子和光学应用都很有吸引力。GeSn:B 是未来 Ge pMOS 器件中源漏材料的候选材料，因为 Sn 相对于纯 Ge 增加了压缩应变，因此可以提高 Ge 沟道性能。需要高 B 浓度才能在源漏材料和金属触点之间获得低接触电阻。因此，为了实现高性能，非常需要最大限度地提高 Sn 含量和 B 浓度。然而，已经表明 CVD 生长的 GeSn:B 显示了 Sn 掺入和 B 浓度之间的权衡（增加 B 掺杂会减少 Sn 掺入）。此外，文献中报道的 CVD 生长的 GeSn:B 工艺的最高 B 浓度被限制在低于 1 × 10 20 cm -3 。这里，我们展示了一种 CVD 工艺，其中 B δ 掺杂层插入 GeSn 层中。我们研究了每个 δ 掺杂层之间的厚度和 δ 掺杂层工艺条件对 GeSn:B 层的晶体质量和掺杂密度的影响。对于相同的 Sn 含量，δ 掺杂工艺导致 B 掺杂比同流工艺高 4 倍。此外，实现了2×10 21 cm -3 的B掺杂浓度和5×10 20 cm -3 的活性浓度。