AVS 51st International Symposium
    Exhibitor Workshop Wednesday Sessions
       Session EW-WeL

Paper EW-WeL1
Quantitative and Chemical State Analysis of Cross-Sectional GaAs/AlAs Superlattice Using the Newly Developed Scanning Auger Nanoprobe

Wednesday, November 17, 2004, 12:00 pm, Room Exhibit Hall B

Session: Advances in SPM and Other Analytical Techniques
Presenter: M. Suzuki, ULVAC-PHI, Inc., Japan
Authors: M. Suzuki, ULVAC-PHI, Inc., Japan
N. Urushihara, ULVAC-PHI, Inc., Japan
N. Sanada, ULVAC-PHI, Inc., Japan
A. Yamamoto, ULVAC-PHI, Inc., Japan
H. Iwai, ULVAC-PHI, Inc., Japan
R. Oiwa, ULVAC-PHI, Inc., Japan
Y. Ohashi, ULVAC-PHI, Inc., Japan
Correspondent: Click to Email
Using Auger electron microscopy, so far, because of the electron beam diameter, thermal/mechanical drift and noise, it has been difficult to achieve a spatial resolution of less than 10 nm. The newly developed scanning Auger nanoprobe (PHI-700) consists of a cylindrical mirror analyzer with a coaxial Schottky field emission electron gun and an eight channel multi-channel detector. The instrument is housed in an acoustic isolation chamber in order to secure a vibration-free analysis environment. The secondary electron imaging and Auger signal imaging spatial resolutions are 6 nm and less than 7 nm, respectively, with an electron beam of 1 nA, 20 kV. We have examined Auger observations of cross-sectional surfaces of epitaxially grown GaAs/AlAs superlattice systems with this instrument. It was easy to obtain Auger elemental mapping showing the GaAs(10 nm)/AlAs(10 nm) structure. Generally speaking, Auger signal intensity is in proportion to the atomic density for the element of interest. Although the atomic densities of As atoms in GaAs and AlAs are almost the same, the As intensity from a GaAs layer is extremely different from that from an AlAs layer. Its intensity, defined as peak-to-peak strength in differential spectra, from GaAs layers is twice as strong as that from AlAs layers. It was also found that the Al peak shape gradually changes from the interface with GaAs layer to the center of AlAs layer, though the Ga peak shape does not change at the center of GaAs layer and at the interface. In the presentation, we will detailedly discuss the sensitivity factors in GaAs and AlAs layers and chemical state variation across the cross-sectional multilayer surface.