Experiment of the Month
Our Dr. Gilani has been studying the properties of sculptured thin films for several years and has supervised four student research projects on their electrical properties. Our source of these films has been the Engineering Science and Mechanics department at Pennsylvania State University, where Dr. Gilani worked as a researcher before taking his teaching position at Millersville. The department at Penn State has helped Dr. Gilani to establish his own preparation facility at Millersville.
Senior Drew Pulsifer has designed and constructed a vacuum evaporation deposition chamber to make Dr. Gilani's films. He took an old (circa 1972) refurbished vacuum system and added to it the stainless steel chamber and top mount shown in the figure. (Mr. Pulsifer plans to go to the Engineering Science and Mechanics graduate program at Penn State under our 4/2 cooperative engineering program.)
The port at the lower left of the chamber allows the operator to look inside at the hot filament surrounding the sample to be evaporated. The filament is heated until the sample is vaporized. Some of the vapor deposits on tilted microscope slides that are mounted on the top plate. Those deposits form the sculptured thin films for Dr. Gilani's research.
The unique feature of these films is their columnar structure: Instead of a uniform film covering the slide, the first atoms to land collect together in small islands. Subsequent atoms land on these islands because their greater height shadows the bare slide surface.
The columns can be grown so that they are tilted relative to the slide surface, and can even be created with a helical growth pattern by rotating the slide about a vertical axis. Drew is currently working on the stepper motor drive for the rotation mechanism.
The most unusual visual feature of the chamber is its large height. To grow the films properly, the atoms should all follow parallel paths as they arrive. The hot filament radiates atoms in all directions. By moving the slide far away, Drew insures that the angle between paths to different parts of the slide are nearly parallel.
We anticipate many years of discovery using the films created by this system.