Search

We present a novel method for fabrication of contacts to nanosize particles. The method is based on conventional optical lithography of GaAs/AlGaAs molecular beam epitaxy grown structures. Taking advantage of the difference in etch rate between GaAs and AlGaAs a narrow gap is formed between metal contacts deposited on the side of a mesa structure. We demonstrate electrostatic trapping of charged metal clusters into these structures using alternating electric fields. [Copyright &y& Elsevier]

We have investigated arrays of quantum dots with elliptical confinement potential on modulation-doped GaAs heterostructures. A laterally structured gate electrode allowed us to tune the system from small isolated dots to large overlapping dots. In far-infrared transmission experiments, we find that the frequency gap between the two resonances with orthogonal linear polarization, which exist in elliptical dots, first decreases and then, very surprisingly, increases again. [Copyright &y& Elsevier]

PbS nanocrystals are an important narrow-gap material for solar cells and photodetectors. Nevertheless, their application may be limited because device performance can be affected by atmospheric conditions. Indeed, the presence of oxygen and/or water can degrade the active layers, possibly leading to device failure. Strategies to address this issue are therefore actively explored. Here we report a solution-processed PbS quantum dot solar cell, consisting of a PbS-silane functionalized reduced graphene oxide (PbS-rGO) layer on top of the PbS absorber film, which enhances device stability, especially when the solar cells are exposed to moisture. Power conversion efficiency (PCE) measurements demonstrate a slower degradation under continuous illumination for solar cells with PbS-rGO. When storing the samples under saturated water vapor, differences are even more remarkable: with PbS-rGO the solar cells essentially maintain their initial PCE, while the PCE of the PbS reference devices is reduced by 50% after 5 days. Scanning electron microscopy, energy dispersive X-ray and X-ray photoelectron spectroscopy reveal the damage to the PbS films and the formation of PbSO x crystals in the PbS reference devices. Such crystals are not observed in the PbS-rGO devices, further supporting the importance of the PbS-rGO barrier layer. [ABSTRACT FROM AUTHOR]