3 research outputs found
Full-Color Single Nanowire Pixels for Projection Displays
Multicolor
single InGaN/GaN dot-in-nanowire light emitting diodes (LEDs) were
fabricated on the same substrate using selective area epitaxy. It
is observed that the structural and optical properties of InGaN/GaN
quantum dots depend critically on nanowire diameters. Photoluminescence
emission of single InGaN/GaN dot-in-nanowire structures exhibits a
consistent blueshift with increasing nanowire diameter. This is explained
by the significantly enhanced indium (In) incorporation for nanowires
with small diameters, due to the more dominant contribution for In
incorporation from the lateral diffusion of In adatoms. Single InGaN/GaN
nanowire LEDs with emission wavelengths across nearly the entire visible
spectral were demonstrated on a single chip by varying the nanowire
diameters. Such nanowire LEDs also exhibit superior electrical performance,
with a turn-on voltage ∼2 V and negligible leakage current
under reverse bias. The monolithic integration of full-color LEDs
on a single chip, coupled with the capacity to tune light emission
characteristics at the single nanowire level, provides an unprecedented
approach to realize ultrasmall and efficient projection display, smart
lighting, and on-chip spectrometer
Babinet-Inverted Optical Yagi–Uda Antenna for Unidirectional Radiation to Free Space
Nanophotonics
capable of directing radiation or enhancing quantum-emitter
transition rates rely on plasmonic nanoantennas. We present here a
novel Babinet-inverted magnetic-dipole-fed multislot optical Yagi–Uda
antenna that exhibits highly unidirectional radiation to free space,
achieved by engineering the relative phase of the interacting surface
plasmon polaritons between the slot elements. The unique features
of this nanoantenna can be harnessed for realizing energy transfer
from one waveguide to another by working as a future “optical
via”
Modulation of the Dirac Point Voltage of Graphene by Ion-Gel Dielectrics and Its Application to Soft Electronic Devices
We investigated systematic modulation of the Dirac point voltage of graphene transistors by changing the type of ionic liquid used as a main gate dielectric component. Ion gels were formed from ionic liquids and a non-triblock-copolymer-based binder involving UV irradiation. With a fixed cation (anion), the Dirac point voltage shifted to a higher voltage as the size of anion (cation) increased. Mechanisms for modulation of the Dirac point voltage of graphene transistors by designing ionic liquids were fully understood using molecular dynamics simulations, which excellently matched our experimental results. It was found that the ion sizes and molecular structures play an essential role in the modulation of the Dirac point voltage of the graphene. Through control of the position of their Dirac point voltages on the basis of our findings, complementary metal–oxide–semiconductor (CMOS)-like graphene-based inverters using two different ionic liquids worked perfectly even at a very low source voltage (<i>V</i><sub>DD</sub> = 1 mV), which was not possible for previous works. These results can be broadly applied in the development of low-power-consumption, flexible/stretchable, CMOS-like graphene-based electronic devices in the future