Thursday, March 12, 2012
3:00pm (334 JFB)
Title: Atomic Scale Study of Dielectric Trap States Using Single Electron Tunneling Force Spectroscopy
The rapid advancement of technology has led to increasingly faster and smaller solid state devices. One reason for this rapid development is the dedicated effort to characterize the defects in the dielectric materials used in solid state electronics. However there are no techniques which allow for characterization of localized electron and hole trap states, in completely nonconducting films, with atomic scale spatial resolution. This talk will focus on the force detected tunneling techniques developed in the Williams lab over the last decade, with an emphasis on the recently developed single electron tunneling force spectroscopy (SETFS) technique. The density of localized trap states in SiO2, Si3N4 and HfO2 measured using SETFS will be compared to experimental results and theoretically predicted values found in the literature. The SETFS results from measurements made on each of these films is in good agreement with standard techniques. However, several states have been characterized that have only been theoretically predicted or are not identified in the literature. Finally, evidence of mobile charge in HfO2 will be presented and a possible mechanism proposed to explain the irreversible nature of the surface charging.