Abstract We demonstrate type-II GaAsSb/GaAsN superlattices (SL) as a suitable structure to form the lattice-matched 1.0–1.15 eV subcell that would allow the implementation of the optimum monolithic multi-junction solar cell design. The separation of Sb and N atoms during growth leads to an improved composition homogeneity and a lower defect density than in the bulk GaAsSbN counterparts. The type-II band alignment SLs provide long radiative lifetimes that facilitate carrier collection as compared to equivalent type-I SLs. Moreover, the radiative lifetime can be controllably tuned through the period thickness, which is not possible in type-I SLs. A reduced period thickness results in enhanced absorption due to increased wavefunction overlap, as well as in a change in the transport regime from diffusive to quasiballistic, providing improved carrier extraction efficiency. As a result, the short period SL single-junction solar cells show an enhanced power conversion efficiency of 134% over the equivalent bulk devices.

中文翻译：

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稀释氮化物 II 型超晶格：克服太阳能电池中块状 GaAsSbN 的困难

摘要 我们展示了 II 型 GaAsSb/GaAsN 超晶格 (SL) 作为一种合适的结构来形成晶格匹配的 1.0-1.15 eV 子电池，这将允许实现最佳的单片多结太阳能电池设计。在生长过程中 Sb 和 N 原子的分离导致比块状 GaAsSbN 对应物的成分均匀性提高和缺陷密度降低。与等效的 I 型 SL 相比，II 型带对齐 SL 提供长的辐射寿命，有助于载流子收集。此外，辐射寿命可以通过周期厚度可控地调整，这在 I 型 SL 中是不可能的。由于波函数重叠增加，以及传输状态从扩散到准弹道的变化，减少的周期厚度导致吸收增强，提供改进的载流子提取效率。因此，短周期 SL 单结太阳能电池的功率转换效率比等效的块状器件高 134%。