Exciton-phonon coupling channels in a ‘strain-free’ GaAs droplet epitaxy single quantum dot

We examine the temperature-dependent excitonic transition energy shift of strain-free GaAs droplet epitaxy (DE) quantum dots (QDs). Interestingly the statistical investigation of QD optical properties enables us to observe three distinct temperature dispersions for four series of DE QDs. We present comparative analyses of the exciton-phonon coupling mechanisms employing various empirical to multi-oscillator models associated with each QD-specific phonon dispersion spectrum. The systematic investigation of such QD exciton-phonon coupling is crucial for fine control of local defects in engineered quantum dot single-photon sources.     

Morphology of Liquid Drops and thin Films on a Solid Surface with Sinusoidal Microstructures

Surface microstructures of solid materials play a significant role in various wetting and dewetting phenomena. In the present paper, the effect of micro- and nano-structures of a substrate surface on the morphology and evolution of liquid droplets and thin films is examined. The governing equations satisfied by droplets and films on a sinusoidal surface are derived by considering van der Waals force, surface tension, gravity and hydrostatic pressure. The morphologies of both liquid droplets and thin films are numerically simulated under various characteristic sizes of roughness. It is found that the droplet shapes show a significant dependence upon the characteristic sizes of substrate microstructures. A thin liquid film on a hydrophilic substrate may have a horizontal surface or replicate the substrate morphology, depending on the wavelength of roughness.The project supported by the National Natural Science Foundation of China (10525210, 10121202) and the Ministry of Education of China.The English text was polished by Keren Wang.     

Transpiration-inspired Capillary for Synchronous Synthesis and Patterning of Silver Nanoparticles

Traditional synthesis strategy of nanomaterials with complicated process and high cost limits their applications. Here, we propose a facile process for the synchronous synthesis and patterning of silver nanoparticles(Ag NPs) through the self-driven microchannel reactor with the capillary effect inspired by transpiration. The evaporation contributes to capillary and accumulation effects in the microchannels. The silver reactant-containing droplets can be spontaneously divided and distributed in multiple microchannels during the whole fabrication process by the capillary effect. The newly formed Ag NPs at the gas-liquid interface can be assembled on both sides of the microchannels by the accumulation effect. The capillary effect decreases the disturbances, which ensures the uniformity of the patterning. By the combination of microchannels with different widths, various Ag NPs-assembled patterns with stable electrical properties are achieved. This efficient strategy with a simple fabrication procedure is towards the technological engineering of nanoscale architected materials.