AVS 46th International Symposium
    Nanometer-scale Science and Technology Division Tuesday Sessions
       Session NS-TuA

Paper NS-TuA3
Interpreting Atomic-Scale Structure in Cross-Sectional STM Images of III-V Superlattices

Tuesday, October 26, 1999, 2:40 pm, Room 612

Session: Innovative Nanoscale Measurements
Presenter: B.Z. Nosho, Naval Research Laboratory
Authors: W. Barvosa-Carter, Naval Research Laboratory
B.Z. Nosho, Naval Research Laboratory
M.J. Yang, Naval Research Laboratory
L.J. Whitman, Naval Research Laboratory
Correspondent: Click to Email
Cross-sectional scanning tunneling microscopy (XSTM) is a powerful method for quantifying the structural and interfacial quality of III-V semiconductor superlattice structures. Although a variety of III-V systems have been studied with XSTM, there are a number of aspects related to image interpretation, particularly on the atomic-scale, that are still a matter of discussion. One rarely discussed issue is that on the (110) cleavage face only every other III-V growth layer within the superlattice can be directly observed by XSTM. This fact can have important consequences when investigating properties of the superlattice such as the roughness between heteroepitaxial layers, interfacial defects, or variations in chemical bonding at the interface. The impact is especially significant when these effects occur predominantly within a volume only two to three monolayers (ML) wide. We are systematically investigating the appearance of III-As and III-Sb bonds at arsenide-antimonide interfaces as a function of cleavage direction and even-versus-odd layers in specially prepared MBE-grown superlattices. We find it is possible to differentiate between the two bond types, but their appearance depends on cleavage-face and layer order. In addition, a model of the measurement of interfacial roughness reveals errors in the measured power spectrum as the actual interface roughness decreases below 2 ML. A simple method for reconstructing the actual power spectrum from the STM data will be described. Funded by the Office of Naval Research and the Air Force Research Laboratory. Present address for W. Barvosa-Carter is HRL Laboratories, Malibu, CA.