Abstract：
The properties of centimeter-sized thin-film compound semiconductors depend upon the morphology and chemical composition of the multiple submicrometer-thick elemental and alloy precursor layers from which they are synthesized. The challenge is to characterize the individual precursor layers over these length scales during a multistep synthesis without altering or contaminating them. Conventional electron and X-ray-based morphological and compositional techniques are invasive, require preparation, and are thus incompatible with in-line synthesis processes. In a proof-of-concept study, we applied confocal laser scanning microscopy (CLSM) as a noninvasive optical imaging technique, which measures three-dimensional surface profiles with nanoscale resolution, to this challenge. Using an array of microdots containing Cu(In,Ga)Se2 semiconductor layers for solar cells as an example, we performed CLSM correlative studies to quantify morphological and layer thickness changes during four stages of a thin-film compound synthesis. Using simple assumptions, we measured the micrometer-scale spatially resolved chemical composition of stacked precursor layers to predict the final material phases formed and predict relative device performance. The high spatial resolution, coupled with the ability to measure sizeable areas without influencing the synthesis at high speed, makes CLSM an excellent prospect for research and quality control tool for thin films.
摘要：
厘米大小的薄膜化合物半导体的性质取决于合成它们的多个亚微米厚的元素和合金前体层的形态和化学组成。挑战是在多步骤合成期间在这些长度尺度上表征各个前体层而不改变或污染它们。传统的基于电子和X射线的形态学和成分技术是侵入性的，需要准备,因此与在线合成工艺不相容。在概念验证研究中,我们应用共聚焦激光扫描显微镜（CLSM）作为一种非侵入性光学成像技术，以纳米级分辨率测量三维表面轮廓，这个挑战。使用含Cu的微点阵列(In，Ga)以太阳能电池用Se2半导体层为例,我们进行了CLSM相关研究，以量化薄膜化合物合成的四个阶段中的形态和层厚变化。使用简单的假设，我们测量了堆叠的前体层的微米尺度空间分辨化学组成，以预测形成的最终材料相并预测相关器件性能。高空间分辨率,加上能够测量相当大的面积而不影响高速合成的能力，使CLSM成为薄膜研究和质量控制工具的良好前景。
