2 research outputs found
Sustained Robust Exciton Emission in Suspended Monolayer WSe_2 within the Low Carrier Density Regime for Quantum Emitter Applications
The development of semiconductor optoelectronic devices is moving toward low power consumption and miniaturization, especially for high-efficiency quantum emitters. However, most of these quantum sources work at low carrier density region, where the Shockley-Read-Hall recombination may dominant and seriously reduce the emission efficiency. In order to diminish the affection of carrier trapping and sustain a strong photoluminescence emission under low power pumping condition, we investigated on the influence of Suspending to monolayered tungsten diselenide, novel two-dimensional quantum material. Not only the PL intensity, but also the fundamental photoluminescence quantum yield has exhibited a huge, order-scale enhancement through suspending, even surprisingly, we found the PLQY improvement revealed far significantly under small pumping power and came out an exponential increase tendency toward even lower carrier density region. With its strong excitonic effect, suspended WSe_2 offers a solution to reduce carrier trapping and participate in non-radiative processes. Moreover, in the low-power range where SRH recombination dominates, suspended WSe_2 exhibited remarkably higher percentage of excitonic radiation compared to contacted WSe_2. Herein, we quantitatively demonstrate the significance of suspended WSe_2 monolayer at low carrier density region, highlighting its potential for developing compact, low-power quantum emitters in the future
Single-Crystal Antimonene Films Prepared by Molecular Beam Epitaxy: Selective Growth and Contact Resistance Reduction of the 2D Material Heterostructure
Single-crystal
antimonene flakes are observed on sapphire substrates
after the postgrowth annealing procedure of amorphous antimony (Sb)
droplets prepared by using molecular beam epitaxy at room temperature.
The large wetting angles of the antimonene flakes to the sapphire
substrate suggest that an alternate substrate should be adopted to
obtain a continuous antimonene film. By using a bilayer MoS<sub>2</sub>/sapphire sample as the new substrate, a continuous and single-crystal
antimonene film is obtained at a low growth temperature of 200 °C.
The results are consistent with the theoretical prediction of the
lower interface energy between antimonene and MoS<sub>2</sub>. The
different interface energies of antimonene between sapphire and MoS<sub>2</sub> surfaces lead to the selective growth of antimonene only
atop MoS<sub>2</sub> surfaces on a prepatterned MoS<sub>2</sub>/sapphire
substrate. With similar sheet resistance to graphene, it is possible
to use antimonene as the contact metal of 2D material devices. Compared
with Au/Ti electrodes, a specific contact resistance reduction up
to 3 orders of magnitude is observed by using the multilayer antimonene
as the contact metal to MoS<sub>2</sub>. The lower contact resistance,
the lower growth temperature, and the preferential growth to other
2D materials have made antimonene a promising candidate as the contact
metal for 2D material devices