7 research outputs found
High-resolution X-ray diffraction analysis of strain distribution in GaN nanowires on Si(111) substrate
Electron Accumulation Tuning by Surface-to-Volume Scaling of Nanostructured InN Grown on GaN(001) for Narrow-Bandgap Optoelectronics
The existence of an uncontrolled electron accumulation
layer near
the surface of InN thin films is an obstacle for the development of
reliable InN-based devices for use in narrow-bandgap optoelectronics.
In this article, we show that this can be regulated by modulating
the surface of the InN grown on GaN(001). By increasing the surface-to-volume
ratio, we can demonstrate a reduction in the surface carrier concentration
from ∼1018 to ∼1017 cm–3. These controlled changes are despite the idea that donor-type surface
states, which contribute to conduction band electrons are reported
to be the main origin of the surface charge density. Additionally,
by evaluating the surface carrier concentration through modeling of
photoluminescence (PL) spectroscopy, we have found a failure of the
Burstein–Moss theory. Conversely, modeling of the longitudinal
optical phonon–plasmon coupled modes measured using Raman spectroscopy,
simulations of InN structures using the k·p method, and Hall effect measurements, where possible,
showed an excellent correlation of the surface electron concentrations.
The large inhomogeneous broadening in the PL, which overwhelms any
broadening due to the Burstein–Moss effect, is understood to
be the result of varying Stark shifts due to varying strain throughout
high surface-to-volume nanostructures, which dramatically affects
the spatially indirect nature of the electron–hole recombination.
Finally, our findings demonstrate how the electron population of 2D
and 3D InN nanostructures can be tuned by structural features, such
as porosity and/or the surface-to-volume ratio
Electron Accumulation Tuning by Surface-to-Volume Scaling of Nanostructured InN Grown on GaN(001) for Narrow-Bandgap Optoelectronics
The existence of an uncontrolled electron accumulation
layer near
the surface of InN thin films is an obstacle for the development of
reliable InN-based devices for use in narrow-bandgap optoelectronics.
In this article, we show that this can be regulated by modulating
the surface of the InN grown on GaN(001). By increasing the surface-to-volume
ratio, we can demonstrate a reduction in the surface carrier concentration
from ∼1018 to ∼1017 cm–3. These controlled changes are despite the idea that donor-type surface
states, which contribute to conduction band electrons are reported
to be the main origin of the surface charge density. Additionally,
by evaluating the surface carrier concentration through modeling of
photoluminescence (PL) spectroscopy, we have found a failure of the
Burstein–Moss theory. Conversely, modeling of the longitudinal
optical phonon–plasmon coupled modes measured using Raman spectroscopy,
simulations of InN structures using the k·p method, and Hall effect measurements, where possible,
showed an excellent correlation of the surface electron concentrations.
The large inhomogeneous broadening in the PL, which overwhelms any
broadening due to the Burstein–Moss effect, is understood to
be the result of varying Stark shifts due to varying strain throughout
high surface-to-volume nanostructures, which dramatically affects
the spatially indirect nature of the electron–hole recombination.
Finally, our findings demonstrate how the electron population of 2D
and 3D InN nanostructures can be tuned by structural features, such
as porosity and/or the surface-to-volume ratio