SiC-like phase and room-temperature photoluminescence of low-k SiOCH films

Carbon-doped hydrogenated silicon oxide (SiOCH) low-k films have been prepared using 13.56 MHz discharge in trimethylsilane (3MS) - oxygen gas mixtures at 3, 4, and 5 Torr sustained with RF power densities 1.3 - 2.6 W/cm2. The atomic structure of the SiOCH films appears to be a mixture the amorphous SiO2-like and the partially polycrystalline SiC-like phases. Results of the infra-red spectroscopy reflect the increment in the volume fraction of the SiC-like phase from 0.22 - 0.28 to 0.36 - 0.39 as the RF power increment. Steady-state near-UV laser-excited (364 nm wavelength, 40±2 mW) photoluminescence (PL) has been studied at room temperatures in the visible (1.8 eV - 3.1 eV) subrange of photon spectrum. Two main bands of the PL signal (at the photon energies of 2.5 - 2.6 eV and 2.8 - 2.9 eV) are observed. Intensities of the both bands are changed monotonically with RF power, whereas the bandwidth of ∼0.1 eV remains almost invariable. It is likely that the above lines are dumped by the non-radiative recombination involving E1-like centres in the amorphous-nanocrystalline SiC-like phases. Such explanation of the PL intensity dependences on the RF power density is supported by results of experimental studies of defect states spectrum in bandgap of the SiOCH films.

Nano-scale morphology and electron spectrum of defect states in low-k SiOCH films

Results of experimental investigations on the relationship between nanoscale morphology of carbon doped hydrogenated silicon-oxide (SiOCH) low-k films and their electron spectrum of defect states are presented. The SiOCH films have been deposited using trimethylsilane (3MS) - oxygen mixture in a 13.56 MHz plasma enhanced chemical vapor deposition (PECVD) system at variable RF power densities (from 1.3 to 2.6 W/cm2) and gas pressures of 3, 4, and 5 Torr. The atomic structure of the SiOCH films is a mixture of amorphous-nanocrystalline SiO2-like and SiC-like phases. Results of the FTIR spectroscopy and atomic force microscopy suggest that the volume fraction of the SiC-like phase increases from ∼0.2 to 0.4 with RF power. The average size of the nanoscale surface morphology elements of the SiO2-like matrix can be controlled by the RF power density and source gas flow rates. Electron density of the defect states N(E) of the SiOCH films has been investigated with the DLTS technique in the energy range up to 0.6 eV from the bottom of the conduction band. Distinct N(E) peaks at 0.25 - 0.35 eV and 0.42 - 0.52 eV below the conduction band bottom have been observed. The first N(E) peak is identified as originated from E1-like centers in the SiC-like phase. The volume density of the defects can vary from 1011 - 1017 cm-3 depending on specific conditions of the PECVD process.

Charge transport and density of trap states in balanced high mobility ambipolar organic thin-film transistors

We report on charge transport and density of trap states (trap DOS) in ambipolar diketopyrrolopyrrole-benzothiadiazole copolymer thin-film transistors. This semiconductor possesses high electron and hole field-effect mobilities of up to 0.6 cm 2/V-s. Temperature and gate-bias dependent field-effect mobility measurements are employed to extract the activation energies and trap DOS to understand its unique high mobility balanced ambipolar charge transport properties. The symmetry between the electron and hole transport characteristics, parameters and activation energies is remarkable. We believe that our work is the first charge transport study of an ambipolar organic/polymer based field-effect transistor with room temperature mobility higher than 0.1 cm 2/V-s in both electrons and holes.

Excited-state dynamics in diketopyrrolopyrrole-based copolymer for organic photovoltaics investigated by transient optical spectroscopy

We investigate the photoexcited state dynamics in a donor-acceptor copolymer, poly{3,6-dithiophene-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]- pyrrole-1,4-dione-alt-naphthalene} (pDPP-TNT), by picosecond fluorescence and femtosecond transient absorption spectroscopies. Timeresolved fluorescence lifetime measurements of pDPP-TNT thin films reveal that the lifetime of the singlet excited state is 185 ± 5 ps and that singlet-singlet annihilation occurs at excitation photon densities above 6 × 1017 photons/cm3. From the results of singlet-singlet annihilation analysis, we estimate that the single-singlet annihilation rate constant is (6.0 ± 0.2) × 109cm3 s-1 and the singlet diffusion length is -7 nm. From the comparison of femtosecond transient absorption measurements and picosecond fluorescence measurements, it is found that the time profile of the photobleaching signal in the charge-transfer (CT) absorption band coincides with that of the fluorescence intensity and there is no indication of long-lived species, which clearly suggests that charged species, such as polaron pairs and triplet excitons, are not effectively photogenerated in the neat pDPP-TNT polymer.

Scaling laws for localised states in a nonlocal amplitude equation

It is well known that, although a uniform magnetic field inhibits the onset of small amplitude thermal convection in a layer of fluid heated from below, isolated convection cells may persist if the fluid motion within them is sufficiently vigorous to expel magnetic flux. Such fully nonlinear(‘‘convecton’’) solutions for magnetoconvection have been investigated by several authors. Here we explore a model amplitude equation describing this separation of a fluid layer into a vigorously convecting part and a magnetically-dominated part at rest. Our analysis elucidates the origin of the scaling laws observed numerically to form the boundaries in parameter space of the region of existence of these localised states, and importantly, for the lowest thermal forcing required to sustain them.

Asset management policies and guidelines of different states in Australia : a comparative analysis

Purpose The purpose of this paper is to explore and compare the asset management policies and practices of six Australian states – New South Wales, Victoria, Queensland, South Australia, Western Australia and Tasmania – to improve understanding of the policy context to best shape policy focus and guidelines. Australian state-wide asset management policies and guidelines are an emergent policy domain, generating a substantial body of knowledge. However, these documents are spread across the layers of government and are therefore largely fragmented and lack coherency. Design/methodology/approach The comparative study is based on the thematic mapping technique using the Leximancer software. Findings Asset management policies and guidelines of New South Wales and Victoria have more interconnected themes as compared to other states in Australia. Moreover, based on the findings, New South Wales has covered most of the key concepts in relation to asset management; the remaining five states are yet to develop a comprehensive and integrated approach to asset management policies and guidelines. Research limitations/implications This review and its findings have provided a number of directions on which government policies can now be better constructed and assessed. In doing so, the paper contributes to a coherent way forward to satisfy national emergent and ongoing asset management challenges. This paper outlines a rigorous analytical methodology to inform specific policy changes. Originality/value This paper provides a basis for further research focused on analyzing the context and processes of asset management guidelines and policies.

Adaptive estimation of hidden semi-Markov chains with parameterised transition probabilities and exponential decaying states

This paper develops maximum likelihood (ML) estimation schemes for finite-state semi-Markov chains in white Gaussian noise. We assume that the semi-Markov chain is characterised by transition probabilities of known parametric from with unknown parameters. We reformulate this hidden semi-Markov model (HSM) problem in the scalar case as a two-vector homogeneous hidden Markov model (HMM) problem in which the state consist of the signal augmented by the time to last transition. With this reformulation we apply the expectation Maximumisation (EM ) algorithm to obtain ML estimates of the transition probabilities parameters, Markov state levels and noise variance. To demonstrate our proposed schemes, motivated by neuro-biological applications, we use a damped sinusoidal parameterised function for the transition probabilities.

Density of trap states in a polymer field-effect transistor

We report a more accurate method to determine the density of trap states in a polymer field-effect transistor. In the approach, we describe in this letter, we take into consideration the sub-threshold behavior in the calculation of the density of trap states. This is very important since the sub-threshold regime of operation extends to fairly large gate voltages in these disordered semiconductor based transistors. We employ the sub-threshold drift-limited mobility model (for sub-threshold response) and the conventional linear mobility model for above threshold response. The combined use of these two models allows us to extract the density of states from charge transport data much more accurately. We demonstrate our approach by analyzing data from diketopyrrolopyrrole based co-polymer transistors with high mobility. This approach will also work well for other disordered semiconductors in which sub-threshold conduction is important.

Reconsidering pro bono : a comparative analysis of protocols in Australia, the united states, the United Kingdom and Singapore

As of now, there is little evidence on the questions of whether pro bono services are effective, whether lawyer charity is a cheaper way to provide them (because it does cost money to do pro bono), or whether it would in fact be more efficient and effective if firms and attorneys stopped giving their time and instead donated money to the organizations already specializing in these clients and causes. Pro bono may or may not be an efficient way of doing socially important work; at this point, we simply do not know

Health states for schizophrenia and bipolar disorder within the Global Burden of Disease 2010 Study

A comprehensive revision of the Global Burden of Disease (GBD) study is expected to be completed in 2012. This study utilizes a broad range of improved methods for assessing burden, including closer attention to empirically derived estimates of disability. The aim of this paper is to describe how GBD health states were derived for schizophrenia and bipolar disorder. These will be used in deriving health state-specific disability estimates. A literature review was first conducted to settle on a parsimonious set of health states for schizophrenia and bipolar disorder. A second review was conducted to investigate the proportion of schizophrenia and bipolar disorder cases experiencing these health states. These were pooled using a quality-effects model to estimate the overall proportion of cases in each state. The two schizophrenia health states were acute (predominantly positive symptoms) and residual (predominantly negative symptoms). The three bipolar disorder health states were depressive, manic, and residual. Based on estimates from six studies, 63% (38%-82%) of schizophrenia cases were in an acute state and 37% (18%-62%) were in a residual state. Another six studies were identified from which 23% (10%-39%) of bipolar disorder cases were in a manic state, 27% (11%-47%) were in a depressive state, and 50% (30%-70%) were in a residual state. This literature review revealed salient gaps in the literature that need to be addressed in future research. The pooled estimates are indicative only and more data are required to generate more definitive estimates. That said, rather than deriving burden estimates that fail to capture the changes in disability within schizophrenia and bipolar disorder, the derived proportions and their wide uncertainty intervals will be used in deriving disability estimates.

Clinton, Bush, and Obama : changing policy and rhetoric in the United States Annual Trafficking in Persons Report

This chapter charts the political transitions in the anti-trafficking agenda and rhetoric of the U.S. Government across three Presidential administrations through a detailed examination of the annual Trafficking in Persons reports released by the Office to Monitor and Combat Trafficking in Persons between 2001 and 2012. We argue that the transitions in language and focus reflect key tensions that have dominated trafficking discourse throughout the Clinton, Bush and Obama Presidencies. These fissures include debate over law enforcement versus rights-based frameworks, competing approaches on victim protection and identification, and ongoing disputes about the relationship between prostitution and human trafficking.

Foreign-currency and monetary geopolitics of United States and its effects on the future of the international system

The US dollar is still considered as the main strategic deposit among the currencies of different countries of the world and the policies of the World Bank and the International Financial Organizations have been and will always be influenced by the US economy. Despite the economic crises and commercial balance deficits in the United States, dollar has maintained its high position in and its domination over foreign exchanges and foreign-currency deposits of the countries. The novelty of the present research relies on its consideration of the political properties of the governments and the geopolitical effects of these countries on the position of their monetary and foreign-currency policies and consequently, on the international financial organizations such as the International Monetary Fund and the World Bank, which can determine the future of international economy and the political relations among countries. Our research proves that the political development of the United States and its geopolitical situation have been of the effective factors on dollar growth; and unless the competitors acquire such a relative advantage, they will not be able to seriously challenge the currency of dollar and the monetary policies of the United States, at least in a short time

Protecting World Heritage sites from the adverse impacts of climate change : obligations for States Parties to the World Heritage Convention

Through its mandate to protect and preserve places of ‘outstanding universal value’, the World Heritage Convention provides an unlikely yet effective tool in global efforts to mitigate climate change. The practical efficacy of the Strategy to Assist States Parties to Implement Appropriate Management Responses (‘the Strategy’), which represents the World Heritage Committee’s primary response to the threats posed by climate change to World Heritage sites, is undermined by its weak stance on mitigation. This paper argues that the World Heritage Convention imposes stronger obligations on States Parties than those contained in the Strategy, including a duty on States Parties to commit to ‘deep cuts’ in greenhouse gas emissions. In order to ensure the continuing success of the World Heritage Convention States Parties must engage in extensive mitigation strategies without delay.

Creating meaning: the cancer survivorship experiences of young adults in Australia, England and the United States

This cross-cultural research examined the phenomenon of cancer survivorship through an analysis of the experiences of adolescents and young adults diagnosed with cancer in Australia, England and the United States of America. The research enhances understanding of how meaning and identity develop in relation to cancer interpretively and socioculturally, and the implications for quality of life in adulthood. In so doing, the study explored the existential challenges young people confront when negotiating illness, identity formation and meaning-making, amid the complex matrix of youth and life stage transitions, cultural norms and practices, and varied healthcare environments.