1 research outputs found
Observation of Asymmetric Nanoscale Optical Cavity in GaAs Nanosheets
GaAs nanosheets with no twin defects,
stacking faults, or dislocations
are excellent candidates for optoelectrical applications. Their outstanding
optical behavior and twin free structure make them superior to traditionally
studied GaAs nanowires. While many research groups have reported optically
resonant cavities (i.e., Fabry–Perot) in 1D nanowires, here,
we report an optical cavity resonance in GaAs nanosheets consisting
of complex 2D asymmetric modes, which are fundamentally different
from one-dimensional cavities. These resonant modes are detected experimentally
using photoluminescence (PL) spectroscopy, which exhibits a series
of peaks or “fringes” superimposed on the bulk GaAs
photoluminescence spectrum. Finite-difference time-domain (FDTD) simulations
confirm these experimental findings and provide a detailed picture
of these complex resonant modes. Here, the complex modes of this cavity
are formed by the three nonparallel edges of the GaAs nanosheets.
Due to the asymmetrical nature of the nanosheets, the mode profiles
are largely unintuitive. We also find that by changing the substrate
from Si/SiO<sub>2</sub> to Au, we enhance the resonance fringes as
well as the overall optical emission by 5Ă— at room temperature.
Our FDTD simulation results confirm that this enhancement is caused
by the local field enhancement of the Au substrate and indicate that
the thickness of the nanosheets plays an important role in the formation
and enhancement of fringes