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

Invited Paper NS+EM+SS-MoA1
Scanning Tunneling Microscopy Studies of Atomic-Scale Structure In Semiconductor Heterostructures

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

Session: Cross-sectional Scanning Tunneling Microscopy of Semiconductors
Presenter: E.T. Yu, University of California, San Diego
Authors: E.T. Yu, University of California, San Diego
S.L. Zuo, University of California, San Diego
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Engineering of advanced heterostructure and nanoscale semiconductor devices requires a detailed understanding of the structure and properties of semiconductor materials and devices at the atomic to nanometer scale. Cross-sectional scanning tunneling microscopy provides unique and powerful capabilities for characterization of structural morphology and electronic properties in semiconductor epitaxial and device structures with spatial resolution at or near the atomic scale. In conjunction with results obtained using complementary characterization techniques, such studies can provide valuable insights into the relationships among epitaxial growth conditions, atomic-scale compositional structure, and various aspects of device behavior. We will discuss a number of recent applications of cross-sectional scanning tunneling microscopy to the characterization of III-V compound semiconductor heterostructures. Studies of InAsP/InP heterostructures, currently of interest for optoelectronic devices operating at 1.3-1.55 microns, have revealed that extensive nanoscale compositional clustering occurs, with As-rich and P-rich clusters bounded preferentially by {111} planes forming in the InAsP alloys. Related studies of InNAsP/InP heterostructures, in which low concentrations (~1-2%) of N are incorporated, have provided information about the influence of N on heterojunction band alignments. And STM images of InAsP/InAsSb superlattices of interest for midwavelength infrared emitters have revealed nanoscale compositional fluctuations in these materials consistent with previously reported observations by electron diffraction of partial ordering in InAsSb alloys.