ABSTRACT
X-ray techniques played a key role in the understanding of the
modifications of the structure of dilute nitrides induced at different
length scales by hydrogenation. X-ray diffraction provided the
scientific community with the first evidence that the modifications
of the electronic properties discussed in Chapter 2 go in parallel
with a remarkable variation of the alloy structure. Advanced
synchrotron radiation X-ray spectroscopy techniques coupled with
ab initio simulations based on density functional theory calculations
provided firm evidence that the effects of hydrogenation of dilute
nitrides are related to the formation of N-H complexes of C2v symmetry, in agreement with infrared (IR) absorption, and that
virtually any single N atom incorporated in the alloy is involved in
the formation of these complexes. X-ray spectroscopies constitute
an innovative approach in the analysis of the three-dimensional
structure of defects in semiconductors, unique in its capacity to
inherently probe and weight all the atomic geometries of the N
local environment and highly complementary to other structural
tools discussed elsewhere in this book. Finally, these techniques
provide a “local view” of themodifications of the electronic structure
consequent to hydrogenation, specific to the dilute species at
the origin of the effects, and complementary to the “average”
electronic properties addressed by the more standard probes used
in Chapter 2.
