Published in J. Electron. Mater. 26, 1342 (1997).
Nanometer-scale studies of nitride/arsenide heterostructures
produced by nitrogen plasma exposure of GaAs
R.S. Goldman R.M. Feenstra
Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
B. G. Briner
IBM Research Division, Yorktown Heights, New York 10598
M.L. O'Steen and R.J. Hauenstein
Department of Physics, Oklahoma State University,
We have investigated the nanometer-scale structure and electronic
properties of nitride/arsenide superlattices
produced by nitridation of a molecular beam epitaxially grown GaAs
surface. Using cross-sectional scanning tunneling microscopy and
spectroscopy, we find that the nitrided layers are not continuous
films, but consist of groups of atomic-scale defects and larger
clusters. We identify the defects and clusters as NAs$
and GaN with dilute As concentration, respectively.
Thus, the nitrided regions consist of alloys from both sides
of the miscibility gap predicted for
the GaAsN system. In addition, spectroscopy on the clusters reveals
an upward shift of the band edges and band gap narrowing, with
significant change in the conduction band structure. We estimate the
contribution of strain to
band gap narrowing in terms of an elasticity calculation
for a coherently strained spherical GaN cluster embedded in GaAs.
Click here for preprint of paper, in pdf format.