Theo Muller

Thermally Induced Nano-Structural and Optical Changes of nc-Si:H Deposited by Hot-Wire CVD

We report on the thermally induced changes of the nano-structural and optical properties of hydrogenated nanocrystalline silicon in the temperature range 200–700 °C. The as-deposited sample has a high crystalline volume fraction of 53% with an average crystallite size of ~3.9 nm, where 66% of the total hydrogen is bonded as ≡Si–H monohydrides on the nano-crystallite surface. A growth in the native crystallite size and crystalline volume fraction occurs at annealing temperatures ≥400 °C, where hydrogen is initially removed from the crystallite grain boundaries followed by its removal from the amorphous network. The nucleation of smaller nano-crystallites at higher temperatures accounts for the enhanced porous structure and the increase in the optical band gap and average gap.

Effect of additional electron acceptor in hybrid P3HT:PCBM:ZnO spin-coated films for photovoltaic application: Effect of additional electron acceptor in hybrid P3HT:PCBM:ZnO spin-coated films

Copyright: 2016 Wiley. Due to copyright restrictions, the attached PDF file only contains the abstract of the full text item. For access to the full text item, kindly consult the publishers website.

Shock fracture replicas for thin film microstructure investigation in a transmission electron microscope

Abstract Pt-C surface replicas were examined by transmission electron microscopy to study the structural details of the surfaces and fracture cross-sections of single films and multilayer thin film coatings. Manual fracturing caused artifacts in the surface and fracture face of multilayer systems. Single films are less sensitive to deformation by external mechanical forces in this fracturing process. Heat shock fracturing applied to multilayer systems and single films resulted in relatively smooth and reproducible cross-sectional areas. Most fracturing methods will reveal the characteristic film microstructures, but more or less artifactive fracture structures are always superimposed on them. The goal of this investigation was to demonstrate that the new heat shock fracturing method minimizes these disturbing artifacts and allows, in a unique way, the correlation of optical and mechanical film properties to the microstructure of the films.

Amorphous and nc-Si:H Intrinsic Thin Films for Solar Cells Applications

This contribution discusses the deposition process and properties of intrinsic silicon thin films processed by the hot wire chemical vapour deposition technique. We review some fundamental characterization techniques that are used to probe into the quality of the material and thus decide its susceptibility to be used as the intrinsic layer in solar cells industry. This paper covers the optical, structural and electrical properties of the material. Results from UV-visible and IR spectroscopy, XRD and Raman scattering, X-section TEM as well as dark and photo-currents are given. It is shown that the thermal activation energy is a good measure of the quality of the sample.

Thin Films in Electron Microscopy

Abstract Thin films play an important role in electron microscopy as they can be used to improve the contrast and stability of specimens, as well as to make specimens electrically conductive. In order to avoid overlapping of specimen and coating structures, it is necessary to understand how thin films are formed in the various coating technologies and how to create them reproducibly as part of the different preparation techniques for electron microscopy. In contrast, electron microscopy can be applied to learn more about the structural details of thin films used, for instance, in the optical coating industry. Heat shock fracturing and Pt-C surface replication of the cross sections resulted in reliable transmission electron micrographs (TEM) of the coating microstructure. These studies demonstrate that, under optimal conditions, it is possible to find a correlation between the measured optical properties and the microstructure of the coatings. TEM replica investigations reveal single events, so they can be...