Scanning Probe Microscopy of Nano-Electronic Structures

Michigan State University, East Lansing MI

Investigators

Abstract

TECHNICAL ABSTRACT This project applies cryogenic scanning probe methods to resolve the quantum structure of nanoelectronic systems in semiconductors and metals. With regard to the semiconductor work, this project will apply subsurface charge accumulation, a specialized technique capable of resolving individual electrons in subsurface systems. The technique will be applied to probe the electron addition spectra of nanofabricated pairs of donor atoms in silicon. These objects can be considered as donor molecules, analogous to hydrogenic molecules in free space. The goal is to perform fundamental tests of the quantum mechanics of these minuscule semiconductor systems. With regard to metallic systems, this project will apply scanning tunneling microscopy to measure the local density of state of cerium-telluride, a layered crystal that contains cerium atoms that exhibit Kondo behavior. Hence this study will directly probe a Kondo lattice system. Scanning probe microscopy research has proven to be an outstanding training ground for young physicists. Moreover, an educational Nanoscience show will be performed and iteratively improved, in conjunction with the Michigan State University Science Theatre. NON-TECHNICAL ABSTRACT As integrated circuits continue to rapidly scale down in size, understanding the nature of electrons in semiconductors and metals trapped by and interacting with individual impurity atoms has become increasingly essential. Advanced microscopic techniques have played and will likely continue to play a key role in developing nanoelectronic devices. This research applies two such techniques: Subsurface Charge Accumulation imaging, and low-temperature Scanning Tunneling Microscopy. Two projects will be conducted. One project will probe and test a true atomic-scale device, composed of only two impurity atoms carefully positioned in silicon. The second project will resolve the properties of conducting electrons in cerium-telluride. In this metal the presence of the magnetic cerium atoms is expected to give surprising properties to the conducting charge. This research will provide a challenging training ground for graduate and undergraduate students, as they master advanced microscopy and sample fabrication techniques. Moreover, an educational Nanoscience show will be performed in conjunction with the Michigan State University Science Theatre. This show will literally bring a hands-on introduction to nanotechnology for students in grades 4-12.