Abstract The gallium gradient of the CIGS film plays a key role for device performance of solar cells. However, a three-stage co-evaporation deposition process at low substrate temperature often produces a pronounced steeper gallium (Ga) gradient, which is detrimental to the transport of carriers and leads to lower conversion efficiency. In this work, we propose a modified low-temperature deposition process by introducing an overlapping process between the 1st stage and the 2nd stage. This modified low-temperature process mitigates the diffusion of In and Ga and facilitates the formation of ideal back gradient. Meanwhile, we have demonstrated the phase transition process of the back gradient during the overlapping process by characterization techniques. With the design of new reaction models during the overlapping process, growth mechanisms of the CIGS film in the modified low-temperature process could be visually displayed. This modified low-temperature process has improved the device efficiency of CIGS solar cells from 14.1% to 16.7%.

中文翻译：

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通过改进的恒定低温沉积工艺实现 Cu(In,Ga)Se2 薄膜的优化镓梯度

摘要 CIGS薄膜的镓梯度对太阳能电池的器件性能起着关键作用。然而，在低衬底温度下的三阶段共蒸发沉积工艺通常会产生明显更陡的镓 (Ga) 梯度，这不利于载流子的传输并导致较低的转换效率。在这项工作中，我们通过在第一阶段和第二阶段之间引入重叠过程，提出了一种改进的低温沉积工艺。这种改进的低温工艺减轻了 In 和 Ga 的扩散，并有助于形成理想的反向梯度。同时，我们通过表征技术证明了重叠过程中反向梯度的相变过程。随着重叠过程中新反应模型的设计，可以直观地显示CIGS薄膜在改性低温工艺中的生长机制。这种改进的低温工艺将 CIGS 太阳能电池的器件效率从 14.1% 提高到 16.7%。