1 research outputs found
Polar Second-Harmonic Imaging to Resolve Pure and Mixed Crystal Phases along GaAs Nanowires
In this work, we report an optical
method for characterizing crystal
phases along single-semiconductor IIIāV nanowires based on
the measurement of polarization-dependent second-harmonic generation.
This powerful imaging method is based on a per-pixel analysis of the
second-harmonic-generated signal on the incoming excitation polarization.
The dependence of the second-harmonic generation responses on the
nonlinear second-order susceptibility tensor allows the distinguishing
of areas of pure wurtzite, zinc blende, and mixed and rotational twins
crystal structures in individual nanowires. With a far-field nonlinear
optical microscope, we recorded the second-harmonic generation in
GaAs nanowires and precisely determined their various crystal structures
by analyzing the polar response for each pixel of the images. The
predicted crystal phases in GaAs nanowire are confirmed with scanning
transmission electron and high-resolution transmission electron measurements.
The developed method of analyzing the nonlinear polar response of
each pixel can be used for an investigation of nanowire crystal structure
that is quick, sensitive to structural transitions, nondestructive,
and on-the-spot. It can be applied for the crystal phase characterization
of nanowires built into optoelectronic devices in which electron microscopy
cannot be performed (for example, in lab-on-a-chip
devices). Moreover, this method is not limited to GaAs nanowires but can
be used for other nonlinear optical nanostructures