AVS 58th Annual International Symposium and Exhibition
    Applied Surface Science Division Wednesday Sessions
       Session AS-WeA

Paper AS-WeA7
Multi-technique Characterization for Interfacial Analysis, Depth Profile and Chemical Imaging

Wednesday, November 2, 2011, 4:00 pm, Room 102

Session: Correlative Analysis - A Multi-technique Approach for Identification and Structure-Property Relationships
Presenter: Satyanarayana Kuchibhatla, Pacific Northwest National Laboratory
Authors: S.V.N.T. Kuchibhatla, Pacific Northwest National Laboratory
V. Shutthanandan, Pacific Northwest National Laboratory
B.W. Arey, Pacific Northwest National Laboratory
C.M. Wang, Pacific Northwest National Laboratory
M.I. Nandasiri, Pacific Northwest National Laboratory
N. Ponnusamy, Pacific Northwest National Laboratory
T. Varga, Pacific Northwest National Laboratory
S. Thevuthasan, Pacific Northwest National Laboratory
F. Liu, Carnegie Mellon University
L. Huang, Carnegie Mellon University
L. Porter, Carnegie Mellon University
R.F. Davis, Carnegie Mellon University
T. Prosa, Cameca Instruments Inc.
Correspondent: Click to Email
Nanoscale interfaces are finding use in a multitude of applications including fuel cells, LEDs etc. In addition, our group at EMSL, Pacific Northwest National Laboratory is interested in understanding the influence of interfaces on energy and environmental applications, in particular, radiation tolerance, and oxygen ion conduction. While a number of techniques are available to synthesize interfaces, their analysis is often challenging. Hence, the fundamental understanding required to develop next generation devices with controlled interfaces is not widely available in the literature. In this context, it is imperative to intelligently combine more than one analytical technique and as appropriate use new techniques with improved spatial and chemical resolutions (better chemical sensitivity and improved mass resolution) to achieve such a goal. Atom Probe Tomography (APT), a relatively new technique that compliments various surface and interfacial analysis tools, is capable of providing 3D-chemical images of various materials including multi-layer thin films with sub-nanometer spatial and a ppm level chemical resolution. This talk will focus on combining the information obtained from high-resolution scanning transmission electron microscopy, high-resolution Rutherford backscattering spectrometry, x-ray photoelectron spectroscopy, atom probe tomography, x-ray reflectivity and diffraction analysis of two sets of multi-layer thin films. The first set of multi-layer thin films is synthesized using oxygen plasma-assisted molecular beam epitaxy consisting of samaria doped cerium oxide and scandia stabilized zirconium oxide. These films are expected to provide significantly enhanced oxygen-ion conduction relative to the films that are made of either of the materials. The second set of films, consisting of GaN, InGaN multi-quantum well structures, is prepared using metal-organic chemical vapor deposition. These structures as green LED active regions were shown to have significant improvements in internal quantum efficiency when employing an InGaN buffer layer to modulate MQW interface roughness. The information such as layer thickness, elemental composition of the layers and interfacial roughness/mixing would be compared from various techniques mentioned earlier. Dopant distribution and any possible intermixing of the layers will be of major interest in the case of ceria-zirconia system. The interfacial roughness and any preferential segregation or clustering of In along with 2D/3D uniformity of the layers will be of most interest in the GaN-InGaN system.