The Thin Films Lab contains some of the latest scientific instruments, to which physics majors at other schools may not be exposed at the undergraduate level. Students who choose to do undergraduate research in the department's thin films lab will have the opportunity to work with an atomic force microscope (AFM), scanning tunneling microscope (STM), UV/VIS/NIR spectrophotometer, materials microscope, vacuum evaporation system, and an array of recently purchased electronic instrumentation. Students will have direct, hands-on experience with the type of equipment they will be working with once they graduate from VMI.
The ability to measure the topology (surface characteristics) of thin films is very important in understanding the fundamental nature of a particular material and how that material may play a role in the creation of certain thin film devices. Optical microscopy is one way of seeing details in the surface of materials. Other methods include scanning electron microscopy, atomic force microscopy, and scanning tunneling microscopy. Each method has its advantages and disadvantages, and not all methods are suitable in certain circumstances.
The department's thin films lab contains a Zeiss Axioskop 2 materials microscope. This microscope allows us to visually image films in brightfield, darkfield, and polarized light from 50x to 1000x. With the Total Interference Contrast attachment we are capable of measuring step heights with 20 nm precision.
The department's thin films lab contains an Atomic Force Microscope (AFM) capable of imaging the surface of materials from 80 (m to less than 1 (m with a resolution of less than 2 nanometers at the lower end. One nanometer (nm) is 10-9 meters. Atomic force microscopy can be used on all types of solid materials and produces a three-dimensional image of the surface. The AFM can operate in either contact or intermittent contact mode (including phase imaging) and can be expanded to include magnetic force microscopy.
The scanning tunneling microscope (STM) works by the principle of quantum tunneling and can image the surface of conductors or semiconductors.
The department's thin film lab has a Perkin-Elmer Lambda 900 UV/VIS/NIR spectrophotometer with a 150 mm integrating sphere, 6( incident specular reflectance attachment, and slide holder for transmission measurements. The instrument is capable of measuring transmitted and specular reflected light from 175 to 3300 nm.
To deposit thin films in a vacuum environment, the thin films lab has a Ladd 30000 vacuum evaporator. The system uses a diffusion pump with liquid nitrogen and can reach 10-7 Torr (1 Torr = 1 mmHg) inside a 12-inch diameter bell jar. Shielded electrodes allow us to deposit solid material either by tungsten boats or filaments.
To characterize the electrical properties of thin films, the lab is equipped with electronic equipment. These include such instruments as a source measure unit, picoammeter, digital multimeters, power supplies, digital phosphor oscilloscope, and RCL meter. These are new instruments from Keithly, Agilent, and Tektronix and are like the ones graduates will find throughout industry or in graduate school.
The lab is outfitted with other equipment typically found in a laboratory setting. A fume hood, nanopure water system, spin coater, computers, and data analysis and programming software are but some of the other equipment that students will find available while pursuing undergraduate research at VMI.
Cadet Researches Polarization Using Thin Films