13 research outputs found
Charged exciton kinetics in monolayer MoSe near ferroelectric domain walls in periodically poled LiNbO
Monolayers of semiconducting transition metal dichalcogenides are a strongly
emergent platform for exploring quantum phenomena in condensed matter, building
novel opto-electronic devices with enhanced functionalities. Due to their
atomic thickness, their excitonic optical response is highly sensitive to their
dielectric environment. In this work, we explore the optical properties of
monolayer thick MoSe straddling domain wall boundaries in periodically
poled LiNbO. Spatially-resolved photoluminescence experiments reveal
spatial sorting of charge and photo-generated neutral and charged excitons
across the boundary. Our results reveal evidence for extremely large in-plane
electric fields of 3000\,kV/cm at the domain wall whose effect is manifested in
exciton dissociation and routing of free charges and trions toward oppositely
poled domains and a non-intuitive spatial intensity dependence. By modeling our
result using drift-diffusion and continuity equations, we obtain excellent
qualitative agreement with our observations and have explained the observed
spatial luminescence modulation using realistic material parameters.Comment: 29 pages, 6 figures, submetted materia
Electrical control of orbital and vibrational interlayer coupling in bi- and trilayer 2H-MoS
Manipulating electronic interlayer coupling in layered van der Waals (vdW)
materials is essential for designing opto-electronic devices. Here, we control
vibrational and electronic interlayer coupling in bi- and trilayer 2H-MoS
using large external electric fields in a micro-capacitor device. The electric
field lifts Raman selection rules and activates phonon modes in excellent
agreement with ab-initio calculations. Through polarization resolved
photoluminescence spectroscopy in the same device, we observe a strongly
tunable valley dichroism with maximum circular polarization degree of in bilayer and in trilayer MoS that are fully consistent
with a rate equation model which includes input from electronic band structure
calculations. We identify the highly delocalized electron wave function between
the layers close to the high symmetry points as the origin of the tunable
circular dichroism. Our results demonstrate the possibility of electric field
tunable interlayer coupling for controlling emergent spin-valley physics and
hybridization driven effects in vdW materials and their heterostructures.Comment: Main manuscript: 10 pages, 4 figures ; Supplemental material: 14
pages, 9 figure
GaN Nanowire Arrays for Efficient Optical Read-Out and Optoelectronic Control of NV Centers in Diamond
Solid-state
quantum emitters embedded in a semiconductor crystal
environment are potentially scalable platforms for quantum optical
networks operated at room temperature. Prominent representatives are
nitrogen-vacancy (NV) centers in diamond showing coherent entanglement
and interference with each other. However, these emitters suffer from
inefficient optical outcoupling from the diamond and from fluctuations
of their charge state. Here, we demonstrate the implementation of
regular n-type gallium nitride nanowire arrays on diamond as photonic
waveguides to tailor the emission direction of surface-near NV centers
and to electrically control their charge state in a p-i-n nanodiode.
We show that the electrical excitation of single NV centers in such
a diode can efficiently replace optical pumping. By the engineering
of the array parameters, we find an optical read-out efficiency enhanced
by a factor of 10 and predict a lateral NV–NV coupling 3 orders
of magnitude stronger through evanescently coupled nanowire antennas
compared to planar diamond not covered by nanowires, which opens up
new possibilities for large-scale on-chip quantum-computing applications