Search

The present work comprises a practical tutorial on the topic of correlative microscopy and its application to optoelectronic semiconductor materials and devices. For the assessment of microscopic structure–property relationships, correlative electron microscopy, combined also with scanning-probe and light microscopy, exhibits a collection of indispensable tools to analyze various material and device properties. This Tutorial describes not only the various microscopy methods but also the specimen preparation in detail. Moreover, it is shown that electron microscopy can serve to monitor phase segregation processes on various length scales in semiconductor nanoparticles and thin films. Algorithms used to extract phase information from high-resolution transmission electron micrographs are explained. [ABSTRACT FROM AUTHOR]

In this study, a promising alternative method for addressing grain boundary issues in hematite (α-Fe2O3)-based photoanodes is presented. The porous α-Fe2O3 films are prepared by dip coating a polymerizable precursor onto fluorine-doped tin oxide (FTO) substrates. The photoelectrochemical (PEC) performance of α-Fe2O3 photoanodes is characterized and optimized through controlling the annealing temperature and the number of deposition cycles. Samples of improved crystallinity consisting of a layer of hematite particles of 50 nm in diameter exhibit highest photoresponses of 1.04 mA cm−2 at 1.23 V versus a reversible hydrogen electrode (RHE), and 2.0 mA cm−2 before the dark current onset at 1.7 VRHE. This study indicates that the PEC performance of hematite can be enhanced greatly by an improved crystallinity, particle texture, and a better control of grain boundary effects. [ABSTRACT FROM AUTHOR]

PbSe nanocrystals have been synthesized by conventional hot injection process and also using microwave technique. For PbSe nanocrystals obtained viahot injection process at 160 °C, the quality of the interface between the isolated and purified nanocrystals, after removal of capping ligands, strongly depends on the structure and stoichiometry of the surface. High resolution transmission electron microscopy has been used to investigate the interface between size selected PbSe nanocrystals. Oriented attachment of nanocrystals is achieved by protonation of oleate capping ligands using wet methanol and subsequent solvent evaporation. The removal of oleate from the surface is monitored using infrared spectroscopy. The attachment between preformed PbSe NCs has taken place exclusively through the {100} facets of the rock-salt lattice. In contrast to other related observations, it is found that nanocrystals can also attach through adjacent {100} facets. We have also studied the shape evolution of cubic PbSe NCs during microwave synthesis using transmission electron microscopy. The formation of PbSe nanocubes is attributed to the higher growth rate in the {111} direction compared to that in the {100} direction. [ABSTRACT FROM AUTHOR]