Multilayer thin films play an important role in our technology today. They can be found in many devices such as magnetic hard disks, microelectronic circuits, and x-ray optical elements. In many of these metal-metal and metal-metalloid multilayers, amorphous layers have been discovered using various techniques such as extended x-ray absorption fine structure (EXAFS) and high resolution transmission electron microscopy (HTEM). These amorphous layers enhance the magnetic and electrical properties of the alloy. They also affect the mechanical and structural properties of the system.
The solid state amorphous reactions (SSAR) occur whether the layers are formed by epitaxy or by sputtering. The amorphous phase occurs if there is a large negative heat of mixing between the initial components.1 This indicates that it requires less energy for the amorphous phase to form than for the crystalline phases to form. The reaction is also limited by diffusion rates. In order for the amorphous phase to form, one of the components must have a much larger diffusion rate in the intermixed layer between the components.
Although SSAR is a very active research subject, no studies have explored the possibility that the formation of amorphous layers might be promoted by adding a third element to the layers. To be effective, the third element should lower the free energy of the system and promote faster diffusion of the mobile component in the system. Research is currently being done on this idea. In this paper, the first stages of this research will be discussed. The research is being conducted on the Co-Si system. The Co-Si system is similar to the Ni-Si system but while the Ni-Si system forms amorphous layers the Co-Si system does not. Ti and Rh are to be used as the third elements in the system. The samples are made by two different sputtering techniques. This will show the effect of the quality of vacuum on the amorphous reaction.
Brandt, Denise, "Stimulation of Amorphous Layers in the Co-Si System by Third Element Additions" (1991). Opportunities for Undergraduate Research Experience Program (OURE). 128.