Environmentally friendly and earth abundant Cu2ZnSnS4 (CZTS) based thin films are potential absorbers for next generation photovoltaics. Their optical properties provide the option to be used as upper cells for Si based tandem solar cells, together with a similar structure to Si, triggering interest in investigation of CZTS/Si tandem cells. However, epitaxially growing CZTS on Si can be challenging. Here, we heteroepitaxially grow tetragonal Cu2ZnSnS4 (CZTS) thin films on single crystalline cubic Si (111) wafers with a 4° miscut by simple and low-cost radio frequency magnetron sputtering from a single target. The CZTS film displays a mirror-like surface with a surface roughness of 8.46 nm. The absorption coefficients of the epitaxial CZTS are over 104 cm−1 at 1.5 eV and 1.0 × 105 cm−1 at 2.1 eV. The bandgap is 1.45 eV, and the photoluminescence lifetime is 7.04 ns. Our results demonstrate the potential of the epitaxial CZTS films fabricated by sputtering on the Si substrate for application in CZTS/Si based tandem solar cells.Environmentally friendly and earth abundant Cu2ZnSnS4 (CZTS) based thin films are potential absorbers for next generation photovoltaics. Their optical properties provide the option to be used as upper cells for Si based tandem solar cells, together with a similar structure to Si, triggering interest in investigation of CZTS/Si tandem cells. However, epitaxially growing CZTS on Si can be challenging. Here, we heteroepitaxially grow tetragonal Cu2ZnSnS4 (CZTS) thin films on single crystalline cubic Si (111) wafers with a 4° miscut by simple and low-cost radio frequency magnetron sputtering from a single target. The CZTS film displays a mirror-like surface with a surface roughness of 8.46 nm. The absorption coefficients of the epitaxial CZTS are over 104 cm−1 at 1.5 eV and 1.0 × 105 cm−1 at 2.1 eV. The bandgap is 1.45 eV, and the photoluminescence lifetime is 7.04 ns. Our results demonstrate the potential of the epitaxial CZTS films fabricated by sputtering on the Si substrate for application in CZTS/Si base...

中文翻译：

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射频磁控溅射在Si上外延生长Cu2ZnSnS4薄膜

环保且富含地球资源的 Cu2ZnSnS4（CZTS）基薄膜是下一代光伏的潜在吸收剂。它们的光学特性为用作硅基串联太阳能电池的上部电池提供了选择，以及与硅相似的结构，引发了对 CZTS/Si 串联电池研究的兴趣。然而，在 Si 上外延生长 CZTS 可能具有挑战性。在这里，我们通过简单且低成本的射频磁控管溅射在单晶立方 Si (111) 晶片上异质外延生长四方 Cu2ZnSnS4 (CZTS) 薄膜，具有 4° 错切。CZTS 薄膜呈现出镜面般的表面，表面粗糙度为 8.46 nm。外延 CZTS 的吸收系数在 1.5 eV 时超过 104 cm-1，在 2.1 eV 时超过 1.0 × 105 cm-1。带隙为 1.45 eV，并且光致发光寿命为7.04 ns。我们的结果证明了通过在 Si 衬底上溅射制备的外延 CZTS 薄膜在 CZTS/Si 基串联太阳能电池中的应用潜力。环境友好且地球含量丰富的 Cu2ZnSnS4（CZTS）基薄膜是下一代光伏的潜在吸收剂。它们的光学特性为用作硅基串联太阳能电池的上部电池提供了选择，以及与硅相似的结构，引发了对 CZTS/Si 串联电池研究的兴趣。然而，在 Si 上外延生长 CZTS 可能具有挑战性。在这里，我们通过简单且低成本的射频磁控管溅射从单个靶材以 4° 错切在单晶立方 Si (111) 晶片上异质外延生长四方 Cu2ZnSnS4 (CZTS) 薄膜。CZTS 薄膜呈现出镜面般的表面，表面粗糙度为 8.46 nm。外延 CZTS 的吸收系数在 1.5 eV 时超过 104 cm-1，在 2.1 eV 时超过 1.0 × 105 cm-1。带隙为 1.45 eV，光致发光寿命为 7.04 ns。我们的结果证明了通过在 Si 衬底上溅射制备的外延 CZTS 薄膜在 CZTS/Si 基片中的应用潜力。