Local strain and tunneling current modulated excitonic luminescence in MoS2 monolayers

The excitonic luminescence of monolayer molybdenum disulfide (MoS2) on a gold substrate is studied by scanning tunneling microscopy (STM). STM-induced light emission (STM-LE) from MoS2 is assigned to the radiative decay of A and B excitons. The intensity ratio of A and B exciton emission can be modulated by the tunneling current, since the A exciton emission intensity saturates at high tunneling currents. Moreover, the corrugated gold substrate introduces local strain to the monolayer MoS2, resulting in significant changes of electronic bandgap and valence band splitting. The modulation rates of strain on A and B exciton energies are estimated as -72 meV/% and -57 meV/%, respectively. STM-LE provides a direct link between exciton energy and local strain in monolayer MoS2 with a spatial resolution <10 nm.

Рентгенолюминесценция нитевидных микроструктур ZnO

The morphology, optical and luminescent properties of an ensemble of ZnO whisker microcrystals on sapphire substrate obtained by gas transport synthesis from zinc and oxygen vapors by the vapor – liquid – crystal mechanism are studied. The ensemble is formed by uniaxial ZnO microcrystallites of two morphologies: a combination of a hexagonal prism and single crystal microrods. The absorption edge of the ensemble of whisker microstructures is located in the 385-395 nm region. The total transmittance of the sample in the visible and near-infrared regions is around 10–20% with a layer thickness around 15–18 μm. The X-ray luminescence spectrum is represented by two bands: narrow peak of excitonic emission with a maximum at 388.3 nm and wide peak of defect-related luminescence in the region of 430–600 nm. The decay time constant for excitonic luminescence is around 1.1 ns (not accounted for the width of the excitation pulse), which was obtained for the first time in undoped ZnO microstructures.

Tunneling-current-induced local excitonic luminescence in p-doped WSe2 monolayers

Probing and controlling excitonic species in a 2D-semiconductor on a metallic support using tunneling electrons as a nanoscale excitation source.

Photoactivation of CdSe Quantum Nanoplatelet Luminescence-=SUP=-*-=/SUP=-

The impact of irradiation with higher and lower quantum energy than that corresponding to the fundamental absorption band of CdSe nanoplatelets has been studied. We show that the irradiation wavelength and oxygen strongly influence the photoluminescence of nanoplatelets. We demonstrate also that irradiation of CdSe nanoplatelets dry layers leads to a reversible change in their photoluminescence quantum yield. Keywords: semiconductor nanoplatelet, excitonic luminescence, trap states, intermittent irradiation.

Люминесцентные и фотоэлектрические свойства гибридных структур на основе многослойного графена и 0D и 2D полупроводниковых квантовых нанокристаллов

Establishing the laws of the mechanisms underlying the interaction of nanostructured materials is one of the most important tasks on the way to creating a new generation of efficient photovoltaic devices. In this paper, we study the luminescent and photoelectric properties of hybrid structures formed on the basis of multilayer graphene nanobelts and semiconductor quantum nanocrystals: 0D-: core-shell CdSe / ZnS quantum dots, and 2D-: CdSe nanoplatelets. It was shown that the multiexponential decay of the excitonic luminescence of CdSe nanoplates at room temperature originates from the delayed luminescence due to the presence of trap states on the surface of the nanoplates. It has been established that in the dry layers of nanoplatelets on a dielectric substrate and in the composition of hybrid structures with graphene nanoribbons, the efficiency of delayed excitonic luminescence of nanoplates increases. It has been demonstrated that the rate of increase in photoconductivity in hybrid structures based on CdSe nanoplatelets is an order of magnitude higher than the rate of this process in similar structures based on CdSe / ZnS quantum dots, which indicates the formation of an effective energy / charge transfer channel from nanoplatelets to graphene nanoribbons.