AVS 45th International Symposium
    Nanometer-scale Science and Technology Division Monday Sessions
       Session NS+EM+SS-MoA

Paper NS+EM+SS-MoA4
Microstructure of Mixed-Anion Interfaces Examined with XSTM@footnote 1@

Monday, November 2, 1998, 3:00 pm, Room 321/322/323

Session: Cross-sectional Scanning Tunneling Microscopy of Semiconductors
Presenter: J. Harper, Texas A&M University
Authors: J. Harper, Texas A&M University
M. Weimer, Texas A&M University
D. Zhang, University of Houston
C.H. Lin, University of Houston
S.S. Pei, University of Houston
Correspondent: Click to Email
The quality of the interfaces between the nearly-lattice-matched 6.1 Å materials (InAs, GaSb, and AlSb) is important for a number of applications, including the development of mid-IR lasers, long-wavelength photodetectors, and resonant-tunneling devices. Cross-sectional scanning tunneling microscopy (XSTM) is a powerful tool for characterizing the heterojunctions in these structures, which pose special challenges for molecular beam epitaxy (MBE) because of the mixed-anion nature of this material system. We have observed a white-noise component in the roughness spectrum of the GaSb-on-InAs interface with XSTM that is associated with the presence of interface point defects; these defects most likely arise from thermodynamically favored anion exchange reactions that occur during the crossover from arsenide to antimonide growth. Abruptness of the InAs-on-GaSb interface, on the other hand, is limited by antimony segregation that causes compositional grading within the arsenic layers. We have quantitatively characterized the Sb fraction as a function of distance from the arsenide-on-antimonide heterojunction, and find this compositional grading is well described by an exponential profile. @FootnoteText@ @footnote 1@ Work supported by the National Science Foundation (DMR-9633011).