Hydrogen refinement during solid phase epitaxy of buried amorphous silicon layers

The effect of hydrogen on the kinetics of solid phase epitaxy (SPE) have been studied in buried amorphous Si layers. The crystallization rate of the front amorphous/crystalline (a/c) interface is monitored with time resolved reflectivity.Secondary ion mass spectrometry(SIMS) is used to examine H implanted profiles at selected stages of the anneals. The H retardation of the SPE rate is determined up to a H concentration of 2.3×10²⁰ cm¯³ where the SPE rate decreases by 80%. Numerical simulations are performed to model the H diffusion, the moving a/c interfaces and the refinement of the H profile at these interfaces. Despite the high H concentration involved, a simple Fickian diffusion model results in good agreement with the SIMS data. The segregation coefficient is estimated to be 0.07 at 575 °C. A significant fraction of the H escapes from the a-Si layer during SPE especially once the two a/c interfaces meet which is signified by the lack of H-related voids after a subsequent high temperature anneal.This research was supported by a grant from the Australian Research Council

Measuring the impact of inquiry mode above and beyond situational characteristics and experimenter contact in research relating to self-reported sexual attitudes and behaviors

Factors related to the research context such as inquiry mode, experimenter contact, and setting may affect participants’ comfort with and willingness to admit to engaging in sensitive sexual behaviors or to disclose certain sexual attitudes. Three-hundred-and-thirty-seven undergraduates (77% female, 41% non-White) completed a survey containing measures of sexual behavior, sexual attitudes, sexual victimization, and sexual perpetration history. The level of experimenter contact (high vs. low contact), setting of completion (in lab vs. out of lab), and inquiry mode (pencil-and-paper vs. computer) were manipulated, and participants were randomly assigned to one of eight conditions I hypothesized that low contact, out of lab, computer conditions would be associated with the highest rates of reported sexual behaviors (including higher frequencies, a wider variety of behaviors, and higher rates of reported victimization and perpetration). I also predicted that these same experimental conditions would be associated with more liberal attitudes towards sex and sexuality. Further, I hypothesized that these effects would be moderated by race, such that differences across conditions would be greater for non-White participants than for White participants because non-White participants might fear that reporting socially undesirable sexual behavior will fuel racial stereotypes. For female participants, a general pattern emerged across sexual behavior measures suggesting that mode interacts with race to impact responding: Non-White women tended to report more sexual behaviors on pencil-and-paper surveys than on computers. White women either demonstrated no mode-related differences or reported more sexual behaviors in computer conditions than in paper-and-pencil conditions. One exception was sexual victimization, with White women reporting more victimization on pencil-and-paper measures than on computer. For attitudinal measures, experimenter contact tended to be the most important experimental variable, though effects were again moderated by race. White women endorsed more liberal attitudes towards sex in high contact conditions, and non-White women endorsed more liberal attitudes in low contact conditions. Evaluation of differences for men was hampered by a small sample of male participants. Overall, these results suggest that methodological factors such as experimenter contact and mode have a significant impact on sexual self-report and the direction and magnitude of impact is often moderated by race

Development of the scientific requirements of an Environmental Management System (EMS) for the pearling (Pinctada maxima) industry

This project has been a successful collaboration between pearl farmers, academic scientists and museum taxonomists and has given the scientific community greater access to remote regions of Australia, facilitating the description of new species to science. It has highlighted the inherent variability and abundant biodiversity of shallow water benthic communities in northern Australia. The study employed an exhaustively designed sampling regime incorporating three spatial scales (10’s of metres, 1-5 km, >100’s km) and random sampling through time. A multi-control sampling strategy was undertaken to give an estimate of the natural variability of the region and to test for benthic impacts at three pearl farms that have been in use for up to 40 years. Multiple lines of evidence all conclude that the variability in benthic conditions at the farms is within the bounds of the natural variability at the reference locations. The main mechanisms that influence the impact of shellfish aquaculture are considered to be; the farming method, the density of the cultivated shellfish (or stocking rate), the water depth of the farm area and the hydrographical conditions in the area (Danovaro et al 2004). All these factors favor the northern Australian cultured pearl industry and would contribute to the lack of a benthic footprint documented by this study. The conclusion drawn from these studies is that current pearl oyster culture techniques in northern Australia have no detectable effect on the sediments of the lease sites. As ongoing or frequent benthic monitoring is logistically challenging and expensive in context of northern Australian pearl farms and cannot be expected to observe anything but natural variability it would not be a wise use of scarce industry funding to include benthic monitoring protocols in the standard EMS for this industry. If major changes to farming practice creates uncertainty in the future on this issue, or political climate requires revalidation of these findings, a further study such as this, conducted as corporate industry research, such as this project, could again test the issue

Deep level transient spectroscopy study for the development of ion-implanted silicon field-effect transistors for spin-dependent transport

A deep level transient spectroscopy (DLTS) study of defects created by low-fluence, low-energy ion implantation for development of ion-implanted silicon field-effect transistors for spin-dependent transport experiments is presented. Standard annealing strategies are considered to activate the implanted dopants and repair the implantation damage in test metal-oxide-semiconductor (MOS) capacitors. Fixed oxide charge, interface trapped charge and the role of minority carriers in DLTS are investigated. A furnace anneal at 950 $\rm ^{o}$C was found to activate the dopants but did not repair the implantation damage as efficiently as a 1000 $\rm ^{o}$C rapid thermal anneal. No evidence of bulk traps was observed after either of these anneals. The ion- implanted spin-dependent transport device is shown to have expected characteristics using the processing strategy determined in this study.Comment: 4 pages, 6 figure

A Robust Solution to the Super-Resolution Phase Problem in Scanning Transmission Electron Microscopy

From a set of images, each of poor resolution, recorded in a transmission microscope under many different incident angles of coherent illumination, it is possible to obtain wavelength-limited resolution even if there is a narrow aperture lying in the back-focal plane of the imaging lens. This is achieved by a deconvolution algorithm which retrieves the phase of the Fourier transform of the specimen. The method accounts for complex components in the transfer function of the lens, is not very sensitive to defocus and is remarkably resilient to noise. It may have important applications in overcoming the resolution limit in the scanning transmission electron microscope (STEM), where such data are readily available

Language and art activities at primary level: the EE dimension

The inter-relationship of language and art with environmental education (EE) within the Primary Education Upgrading Prograrnne (PEUP) in Bophuthatswana is described and discussed

Clay as Thermoluminescence Dosemeter in diagnostic Radiology applications

As part of efforts to isolate and utilize local and naturally occurring materials for development of thermoluminescece dosemeters and other technologies, an earlier report had shown that Nigerian clay showedprospects of utility as a thermoluminescence dosemeter (TLD). This paper reports the investigation of the basic thermoluminescence properties of clay at x-rays in the diagnostic radiology range, including dose monitoring in abdominal radiography. Clay sourced from Calabar, Nigeria, was tested for thermoluminescence response after irradiation at diagnostic radiology doses, including application in abdominal radiography dose monitoring in a clinical setting.Results show that thermoluminescence (TL) output in natural clay is very low, but demonstrates enhanced performance with the addition of common salt. Specific TL characteristics of good repeatability for individual and batched pellets (variability index of 3.08%) and a high degree of trap emptying were observed. It had a glow curve peak at 275 C; with traces of spurious thermoluminescence emission at the reader anneal temperature. There was evidence of good batch homogeneity (< 30%) and a similar pattern of dose absorption in abdominal radiography with commercialLithium Fluoride (LiF TLD-100). A high fading rate (over 30% in twelve hours) and low sensitivity (12 times less than LiF TLD-100) however, signal the unacceptability of clay as aTLD in diagnostic radiology in the forms studied. Clay demonstrates poor TL response at diagnostic radiology doses. However, it's water absorbing property offers a means of overcoming the hygroscopic nature of common salt. This could beexplored to improve the use of sodium chloride as a radiation detector.Keywords: Clay, Thermoluminescence, Dosemeter, Detector, Radiology, x-rays