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TOF-SIMS studies of Molecular Thin Films and Oxides for Optoelectronic Applications

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Title: TOF-SIMS studies of Molecular Thin Films and Oxides for Optoelectronic Applications
Authors: Yang, Junwei
Item Type: Thesis or dissertation
Abstract: Dynamic secondary ion mass spectrometry (SIMS) is a mature surface analytical technique particularly in the semiconductor industry where it has been used for process development, process monitoring and troubleshooting. This technique now is capable of sub-nanometre depth resolution, parts per billion sensitivity and lateral resolution in the tens of nanometre range. In the past few years, the application of SIMS has been increasing its range into other branches of materials including ceramic and glasses, metals, polymers and biomaterials. Currently, the processing and the development of devices of organic semiconductors are becoming more mature, whilst the materials characterisation has not currently been adapted to characterise organic semiconductors. There are a range of interesting questions that are still staying open. For example there are efforts made trying to determine the composition in blends of organic films and the roughness of interfaces between the films using techniques such as transmission electron microscopy (TEM). The motivation of this research is to extend the strengths of SIMS to organic materials and in particular, concentrate on the application of SIMS to analyse soft organic phthalocyanine thin films as a function of depth. There are four main research questions in this study. Firstly, time of flight secondary ion mass spectrometry (TOF-SIMS) was used as a surface analytical tool to quantify the degree of blends between metal and metal-free phthalocyanine films. The samples analysed were 100%, 50%, 10%, 1%, 0.1% and 0% copper phthalocyanine (CuPc) to metal-free phthalocyanine (H2Pc). Secondly, A methodology was developed to distinguish between phthalocyanine molecules with very similar masses and structures, analysing composition in multilayer organic films and drawing 3D map of multilayer films. Lastly, TOF-SIMS was used as a quantification tool to detect the presence of metal oxide formed on the surface of the sample after UV treatment of metal phthalocyanine films. TOF-SIMS was also used as a surface analysis tool, to detect metal dopants within the substrate after the UV treatment of metal phthalocyanine films. This study showed that it is possible to quantify the compositions of blends between metal and metal-free phthalocyanine films. The SIMS parameters developed from this study can be used to analyse soft organic films such as phthalocyanine films. This could be a starting point to characterise complex phthalocyanine heterostructures. Due to the TOF-SIMS parameters used in this study which are not fully optimised for the detection of metal dopants within the substrate, the presence of zinc dopants after UV degradation is not conclusive from this study. However, this study showed, by using SIMS, that it is possible to create metal oxide using UV degradation of metal phthalocyanine films.
Issue Date: May-2012
Date Awarded: Jul-2012
URI: http://hdl.handle.net/10044/1/9859
DOI: https://doi.org/10.25560/9859
Supervisor: Heutz, Sandrine
McPhail, David
Ryan, Mary
Department: Materials
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Master of Philosophy (MPhil)
Appears in Collections:Materials PhD theses



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