Atomic scale chemical and structural characterization of internal interfaces with atom probe tomography

Abstract

Many nanoscale material systems require both structural and compositional characterization in order to be able to fully predict their electrical, magnetic, or optoelectronic behaviors. Traditional characterization techniques such as (S)TEM, SIMS, and XPS currently lack either spatial or chemical resolution needed for characterization of nanoscale devices. 3-dimensional atom probe has recently been utilized to determine the chemical and structural abruptness in a variety of materials with sub-nm spatial resolution and ~10ppm chemical resolution. In this talk, recent work utilizing a laser pulsed local electrode atom probe (LEAP) for the characterization of Photovoltaic devices will be illustrated. Specifically, dopant and H depth profiling in <10nm thick a-Si layers has been illustrated with ~1018/ cm3 chemical resolution. Additionally, interfacial abruptness in III¿V PV devices with a quantum well active region is illustrated with <1nm spatial resolution. Grain boundary analysis in metallic and semiconducting materials is also illustrated following site-specific FIB specimen preparation. Finally, transparent conducting oxide top contact layers have been analyzed for phase separation and following direct-write Maskless Mesoscale Materials Deposition (M3D) processing from polymeric precursors. Utilizing the laser pulsed LEAP for the analysis of TCOs also has illustrated the possibilities for analyzing lower conductivity, transparent materials such as dielectrics. The limitations and possible future applications to dielectric and ferroelectric applications will be discussed.