RUI: Fundamental Studies of a-Ge:H and a-SiGe:H Deposition by Reactive Magnetron Sputtering

技术说明：本项目旨在更好地了解与光伏应用相关的直流反应磁控溅射材料沉积氢化非晶锗（a-Ge:H）和氢化非晶硅锗（a-SiGe:H）。该方法的重点是在生长过程中进入表面的能量和动量通量在决定膜性质中的作用，以及氢在膜中的结合机制的阐明。利用不平衡磁控管和外加磁场系统地改变等离子体密度；将使用射频偏压来控制离子能量。等离子体特性将用等离子体探针测定。溅射原子输运的蒙特卡罗模拟将用于确定高能中性轰击的能量、通量和角分布，并通过沉积剖面的实验研究加以验证。氢的结合动力学将通过质谱和发射光谱进行研究。这些数据将通过光学传输和反射光谱、红外吸收光谱、卢瑟福后向散射、弹性后坐力探测、光和暗电导率以及亚间隙吸收光谱测定，与所得薄膜的成分、结构、光学和电性能相关联。这些信息将为理解这些材料与氢化非晶硅相比性能较差的原因提供坚实的基础，并应导致这些技术重要材料的进一步优化。本研究可望对溅射沉积生长薄膜的基本认识作出重要贡献。本项目主要从事与电子、光子学相关的基础材料研究，有效地将科研与教育结合起来。这项研究将与四年制文理学院马卡莱斯特学院（Macalester College）的本科生研究助理合作进行。该项目将通过提供独特的研究机会，提供学年独立研究项目的选择，以及加强物理课程中与材料科学相关的课程，为学生提供有价值的研究训练。它还将成为本科院校材料研究的典范，以及文理学院物理系研究与教学结合的典范。

TECHNICAL EXPLANATION: This project aims for greater understanding of the deposition of hydrogenated amorphous germanium (a-Ge:H) and hydrogenated amorphous silicon-germanium (a-SiGe:H) by direct current reactive magnetron sputtering-materials with relevance to photovoltaic applications. The approach focuses on the role of energy and momentum flux into the surface during growth in determining film properties, and the elucidation of the mechanism of hydrogen incorporation in the film. The plasma density will be systematically varied using an unbalanced magnetron and an external magnetic field; a radio frequency bias will be used to control the ion energy. Plasma characteristics will be determined using plasma probes. Monte Carlo simulations of sputter atom transport will be utilized to determine the energy, flux, and angular distribution of energetic neutral bombardment, to be verified by experimental studies of deposition profiles. Hydrogen incorporation kinetics will be studied by mass spectrometry and optical emission spectroscopy. These data will be correlated with compositional, structural, optical, and electrical properties of the resulting films as determined by optical transmission and reflection spectroscopy, infrared absorption spectroscopy, Rutherford Back Scattering, Elastic Recoil Detection, photo and dark conductivity, and subgap absorption spectroscopy. This information will provide a sound basis for understanding the causes of the inferior properties of these materials compared to hydrogenated amorphous silicon, and should lead to further optimization of these technologically important materials. This study is expected to make an important contribution to basic understanding of thin film growth by sputter deposition.. NON-TECHNICAL EXPLANATIONThe project addresses fundamental materials research with strong technological relevance to electronics and photonics, and effectively integrates research and education. The research will be carried out in collaboration with undergraduate research assistants at Macalester College, a four-year liberal arts college. The project will provide valuable research training for students by providing unique research opportunities, by providing options for academic year independent research projects, and by enhancing courses related to materials science in the physics curriculum. It will also serve as a model for materials research at an undergraduate institution, and as a model for the integration of research and teaching in a liberal arts college physics department.