Sapkota Dhurba R, Ramanujam Balaji, Pradhan Puja, Alaani Mohammed A Razooqi, Shan Ambalanath, Heben Michael J, Marsillac Sylvain, Podraza Nikolas J, Collins Robert W
Wright Center for Photovoltaics Innovation & Commercialization, Department of Physics & Astronomy, University of Toledo, Toledo, OH 43606, USA.
Virginia Institute of Photovoltaics, Old Dominion University, Norfolk, VA 23529, USA.
Materials (Basel). 2024 Aug 14;17(16):4048. doi: 10.3390/ma17164048.
Flux calibrations in multi-source thermal co-evaporation of thin films have been developed based on real-time spectroscopic ellipsometry (RTSE) measurements. This methodology has been applied to fabricate CuInSe (CIS) thin film photovoltaic (PV) absorbers, as an illustrative example, and their properties as functions of deposition rate have been studied. In this example, multiple Cu layers are deposited step-wise onto the same Si wafer substrate at different Cu evaporation source temperatures (). Multiple InSe layers are deposited similarly at different In source temperatures (). Using RTSE, the Cu and InSe deposition rates are determined as functions of and . These rates, denoted , are measured in terms of effective thickness which is the volume per planar substrate area and accounts for surface roughness variations with deposition time. By assuming that all incident metal atoms are incorporated into the films and that the atomic concentrations in the deposited material components are the same as in single crystals, initial estimates of the Cu and In atom fluxes can be made versus and . Applying these estimates to the co-evaporation of a set of CIS films from individual Cu, In, and Se sources, atomic concentration corrections can be assigned to the Cu and InSe calibration films. The corrections enable generation of a novel calibration diagram predicting the atomic ratio = [Cu]/[In] and rate within the - plane. Using this diagram, optimization of the CIS properties as a PV absorber can be achieved versus both and .
基于实时椭圆偏振光谱（RTSE）测量，已开发出多源热共蒸发薄膜中的通量校准方法。作为一个示例，该方法已应用于制备铜铟硒（CIS）薄膜光伏（PV）吸收层，并研究了其作为沉积速率函数的特性。在这个示例中，多个铜层在不同的铜蒸发源温度（）下逐步沉积到同一个硅片衬底上。多个铟硒层在不同的铟源温度（）下类似地沉积。使用RTSE，确定铜和铟硒的沉积速率作为 和 的函数。这些速率，表示为 ，是以有效厚度来测量的，有效厚度是每平面衬底面积的体积，并考虑了随沉积时间变化的表面粗糙度。通过假设所有入射的金属原子都并入薄膜中，并且沉积材料组分中的原子浓度与单晶中的相同，可以对铜和铟原子通量相对于 和 进行初步估计。将这些估计应用于从单个铜、铟和硒源共蒸发一组CIS薄膜时，可以为铜和铟硒校准薄膜分配原子浓度校正。这些校正能够生成一个新颖的校准图，预测原子比 = [铜]/[铟]以及 -平面内的速率 。使用这个图，可以相对于 和 实现CIS作为光伏吸收层的性能优化。
