Novel physical phenomena can emerge in low-dimensional nanomaterials. Bulk MoS2, a prototypical metal dichalcogenide, is an indirect bandgap semiconductor with negligible photoluminescence. When the MoS2 crystal is thinned to monolayer, however, a strong photoluminescence emerges, indicating an indirect to direct bandgap transition in this d-electron system. This observation shows that quantum ...

A striking correlation between infrared photoinduced absorption spectra and the photoluminescence from silicon nanocrystals indicates that quantized electronic sublevels of the nanocrystals are resonantly coupled to surface vibrational modes via a polarization field produced by coherent longitudinal polar vibrations. Our experimental results and model support the assumption that the mechanism r...

The acid oxidation of carbon nanotube generally results in opening the close ends of the nanotube and to make surface modifications. Herewith, Multiwall carbon nanotubes (MWCNTs) were oxidized in acids at high temperature experimental conditions which led to the formation of graphene quantum dots (GQDs).   High resolution transmission electron microscope (HRTEM), energy dispersive X-ray spectro...

We discuss properties of cw and time-resolved photoluminescence (PL) as well as photoluminescence excitation (PLE) from co-doped ZnSe:Cl,N samples. These samples are characterized by the presence of the potential fluctuations due to charged donors and acceptors. We compare intensity dependent cw PL with the theory and find a good agreement. We also find that the material parameters obtained fro...

Realistic calculations of photoluminescence spectra for a 20 nm quantum well at a filling factor ν = 1/3 are presented. The new states formed from charged excitons (trions) by correlation with the surrounding electrons are identified. These “quasiexcitons” differ from usual excitons and trions by having fractionally charged constituents. Their binding energies and emission intensities depend on...

Articles you may be interested in RHEED transients during InAs quantum dot growth by MBE Low density of self-assembled InAs quantum dots grown by solid-source molecular beam epitaxy on InP(001) Enhanced photoluminescence of InAs self-assembled quantum dots grown by molecular-beam epitaxy using a " nucleation-augmented " method Appl. Area-controlled growth of InAs quantum dots and improvement of...

Direct measurements of the diffusion length of excitons in air-suspended single-walled carbon nanotubes are reported. Photoluminescence microscopy is used to identify individual nanotubes and to determine their lengths and chiral indices. Exciton diffusion length is obtained by comparing the dependence of photoluminescence intensity on the nanotube length to numerical solutions of diffusion equ...

We report studies of photoluminescence from polycrystalline ZnO films deposited on sapphire as a function of the in situ oxygen pressure during growth and ex situ annealing. The ultraviolet photoluminescence was observed to increase by more than two orders of magnitude as a result of the annealing treatment. Enhanced cathodoluminescence was observed from the same films. The role of oxygen defec...

We present a study of the hydrostatic-pressure dependence of the photoluminescence from In0.5Al0.5As/Al0.25Ga0.75As self-assembled quantum dots. Three distinct regions of quantum-dot peak-energy shift with pressure are observed and are attributed to energy level crossings and band mixing effects. In addition, a large reduction in photoluminescence linewidth with applied pressure is noted. © 199...