Analysis of organic multilayered samples for optoelectronic devices by (low-energy) dynamic SIMS

The increasing sophistication of optoelectronic devices requires molecular-level dimensional control in the fabrication of multilayered structures with specifically engineered interfaces. However, the effectiveness of growth and doping strategies devised to achieve the desired device structures often remains unverified due to the lack of adequate characterization techniques. This is particularly true for devices based on conjugated organic compounds, which find increasing use in energy applications (e.g. organic light emitting diodes and organic photovoltaic cells, etc.). The buried interfaces are simply inaccessible or suffer damage when using conventional characterization techniques. In a current project, we address this challenge by advancing the development of low-energy (LE) SIMS for the analysis of organic-based optoelectronic materials systems. In the present study, multilayered organic thin films have been analyzed, varying experimental conditions such as the impact energies for Cs + bombardment in the MCs x + and M − mode on a Cameca Sc-Ultra instrument to investigate the ionization mechanisms as well as the atomic mixing at the interfaces between layers, and the degradation of the organic information. Low-energy dynamic SIMS proved to be a reliable tool for the characterization of organic multilayered optoelectronic devices: MCs x + secondary ions provide information about the distribution of elements within the samples, while negative fragments that are characteristic for the different molecules give information about the structure. Copyright © 2010 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79419/1/3451_ftp.pd

Very low effective Schottky barrier height for erbium disilicide contacts on n-Si through arsenic segregation

The segregation of As+ ions implanted into thin Er films deposited on n-Si substrates is studied after ErSi2-x formation. The same lowering of the effective Schottky barrier height (SBH) below 0.12 eV is obtained at moderate annealing temperatures, regardless of the redistribution of As dopants at the ErSi2-x/Si interface. On the other hand, if the implanted dose is slightly enhanced, the annealing temperature required to reach sub-0.12-eV effective SBH can be further reduced. This process enables the formation of very low effective SBH ErSi2-x/n-Si contacts with a low thermal budget

A benzoxazine/substituted borazine composite coating: A new resin for improving the corrosion resistance of the pristine benzoxazine coating applied on aluminum

In this paper, laboratory synthesized Phenol-paraPhenyleneDiAmine (P-pPDA) benzoxazine containing different amounts of B-trimesityl-N-triphenylborazine was applied by spin coating on aluminum and thermally cured. The addition of the borazine derivative (borazine 1) does not appear to modify the curing characteristics of the P-pPDA matrix itself as shown by FTIR, DSC and DEA analyses; however, some interactions - chemical and/or physical (co-crystallization) – between P-pPDA and borazine 1 cannot be excluded. The microstructure of the composites is characterized by a two phase system consisting of a dispersion of nanosized (10–20 nm) clusters for the lowest borazine 1 concentration (0.5 wt%), evolving towards bigger (100–200 nm), agglomerated clusters for higher borazine 1 concentrations (3 wt%) and finally, continuous, dendritic structures within the P-pPDA matrix for the highest borazine 1 concentration (10 wt%). The benzoxazine composite coating containing 0.5 wt% trimesitylborazine derivative showed a largely increased and durable ability to protect the aluminum substrate. It is shown that a highly capacitive behavior and durable barrier properties can be obtained for P-pPDA coatings containing such a low amount of borazine derivative homogeneously dispersed in the benzoxazine matrix. For concentrations of 3 wt%, as agglomeration took place and dendrites appeared for the highest concentration of borazine derivative (10 wt%), the corrosion resistance decreased with time

Vps34 PI 3-kinase controls thyroid hormone production by regulating thyroglobulin iodination, lysosomal proteolysis and tissue homeostasis

BACKGROUND: The production of thyroid hormones (T3, T4) depends on the organization of the thyroid in follicles, which are lined by a monolayer of thyrocytes with strict apico-basal polarity. This polarization supports vectorial transport of thyroglobulin for storage into, and recapture from, the colloid. It also allows selective addressing of channels, transporters, ion pumps and enzymes to their appropriate basolateral (NIS, SLC26A7 and Na+/K+-ATPase) or apical membrane domain (Anoctamin, SLC26A4, DUOX2, DUOXA2 and TPO). How these actors of T3/T4 synthesis reach their final destination remains poorly understood. The PI 3-kinase (PI3K) isoform Vps34/PIK3C3 is now recognized as a main component in the general control of vesicular trafficking and of cell homeostasis via the regulation of endosomal trafficking and autophagy. We recently reported that conditional Vps34 inactivation in proximal tubular cells in the kidney prevents normal addressing of apical membrane proteins and causes abortive macroautophagy. // METHODS: Vps34 was inactivated using a Pax8-driven Cre recombinase system. The impact of Vps34 inactivation in thyrocytes was analyzed by histological, immunolocalization and mRNA expression profiling. Thyroid hormone synthesis was assayed by 125I injection and serum plasma analysis. // RESULTS: Vps34cKO mice were born at the expected Mendelian ratio and showed normal growth until postnatal day 14, then stopped growing and died at around 1 month of age. We therefore analyzed thyroid Vps34cKO at postnatal day 14. We found that loss of Vps34 in thyrocytes causes: (i) disorganization of thyroid parenchyma, with abnormal thyrocyte and follicular shape and reduced PAS+ colloidal spaces; (ii) severe non-compensated hypothyroidism with extremely low T4 levels (0.75 ± 0.62 g/dL) and huge TSH plasma levels (19,300 ± 10,500 mU/L); (iii) impaired 125I organification at comparable uptake and frequent occurrence of follicles with luminal thyroglobulin but non-detectable T4-bearing thyroglobulin; (iv) intense signal in thyrocytes for the lysosomal membrane marker, LAMP-1, as well as thyroglobulin and the autophagy marker, p62, indicating defective lysosomal proteolysis, and (v) presence of macrophages in the colloidal space. // CONCLUSIONS: We conclude that Vps34 is crucial for thyroid hormonogenesis, at least by controlling epithelial organization, Tg iodination as well as proteolytic T3/T4 excision in lysosomes