At right, a researcher is inserting a sample into a the researcher to look at the interface and surface simul- BEEM (Ballistic Electron Emission Microscopy) taneously to study the operation and performance of a system, described as a system that allows scien- structure. tists to peer into the electronic structures of semiconduc- Among BEEM advantages cited by JPL are the option i tor devices. below are the components of the BEEM to inject either electrons or holes to nondestructively I I system, which was developed at Jet Propulsion image barrier heights and characterize devices electroni- Laboratory (JPL), engineered by Atomis, Inc., Berkeley, cally; the ability to image interface and surface using an California and introduced to the commercial marketplace instrument that operates in air, liquid or in a vacuum; and r; by SurfaceAnterface Inc., Mountain View, California. the potential to observe processes such as molecular BEEM is a research instrument invented by a beam epitaxy (crystal growth) in situ. trio of scientists at JPL's Center for Microelectronics Technoloa-v": Dou-g las Bell, Michael H. Hecht and William J. Kaiser. The invention won for the trio an R&D 100 Award in 1990 because of the significance of the technol- ogy to microelectronic research. Analytical instruments that produce images of surface structures are in wide use, but BEEM goes a step further with the ability to . image underlying layers or interfaces. BEEM was conceived as a tool for advanced research on semiconductor devices. Co-inventor Michael Hecht says that "almost everything of interest in semicon- ductor devices happens at interfaces, not on surfaces." BEEM injects a tiny current into a metal layer and the electrons travel ballistically through the metal: this allows