Learning to live with clover scorch

Recent research has increased our understanding of clover scorch disease in Western Australia. An economic control has yet to be developed but it appears that management can be adjusted to reduce damage to pastures and there is scope for using resistant species and less susceptible cultivars to escape the disease. A major research programme is in progress

Progress in clover scorch research

Considerable progress has been made with the clover scorch problem since the devastation of the 971 epidemic when intensive research began. Over 2000 varieties and crossbreds of subterranean clover from various collections have been screened for resistance resulting in the release of the first resistant clover, Esperance, this year. Benefits of fungicidal spraying have been demonstrated and low cost spraying programmes for grazed pastures, and seed and hay crops are under field investigation

Don't Mistake Business Plans for Planning (It May Be Dangerous to Your Financial Health)

Most academic research concerning business plans suggests that business plans  improve the performance of new firms, and virtually all textbooks related to small business advise ent repreneurs to prepare plans before sta rting a business. A survey of the chief executive officers (CEO) in the INC. 500 (America's 500 fastest growing, privatel y held  small  firms )  suggests  otherwise-fewer  than  twenty percent of the respondents indicated that  they had prepared complete business plans before start-up. Furthermore, firms which prepared business plans were less profitable when entering the rapid  growth phase  than those which did not. This article explores benefits and limitations of  business plan preparation

Pre-Export Planning and Start-up Export Performance for Small Electronics Manufacturers

An increasing number of small businesses are seeking customers in foreign countries. At this time, however, our knowledge of small business successful export practices is limited. To increase our export understanding, it has been suggested that research should examine in more depth the relationship between export planning and performance.   Based on a sample of eighteen small firms in the electronics industry, weak support was found for the hypothesis that the level of formal export planning is positively related to export performance. Areas for future research and limitations of the study are also discussed

Detection of low energy single ion impacts in micron scale transistors at room temperature

We report the detection of single ion impacts through monitoring of changes in the source-drain currents of field effect transistors (FET) at room temperature. Implant apertures are formed in the interlayer dielectrics and gate electrodes of planar, micro-scale FETs by electron beam assisted etching. FET currents increase due to the generation of positively charged defects in gate oxides when ions (121Sb12+, 14+, Xe6+; 50 to 70 keV) impinge into channel regions. Implant damage is repaired by rapid thermal annealing, enabling iterative cycles of device doping and electrical characterization for development of single atom devices and studies of dopant fluctuation effects

Processing Issues in Top-Down Approaches to Quantum Computer Development in Silicon

We describe critical processing issues in our development of single atom devices for solid-state quantum information processing. Integration of single 31P atoms with control gates and single electron transistor (SET) readout structures is addressed in a silicon-based approach. Results on electrical activation of low energy (15 keV) P implants in silicon show a strong dose effect on the electrical activation fractions. We identify dopant segregation to the SiO2/Si interface during rapid thermal annealing as a dopant loss channel and discuss measures of minimizing it. Silicon nanowire SET pairs with nanowire width of 10 to 20 nm are formed by electron beam lithography in SOI. We present first results from Coulomb blockade experiments and discuss issues of control gate integration for sub-40nm gate pitch levels

Stark shift and field ionization of arsenic donors in 28^{28}Si-SOI structures

We develop an efficient back gate for silicon-on-insulator (SOI) devices operating at cryogenic temperatures, and measure the quadratic hyperfine Stark shift parameter of arsenic donors in isotopically purified $^{28}$Si-SOI layers using such structures. The back gate is implemented using MeV ion implantation through the SOI layer forming a metallic electrode in the handle wafer, enabling large and uniform electric fields up to $\sim$ 2 V/$\mu$m to be applied across the SOI layer. Utilizing this structure we measure the Stark shift parameters of arsenic donors embedded in the $^{28}$Si SOI layer and find a contact hyperfine Stark parameter of $\eta_a=-1.9\pm0.2\times10^{-3} \mu$m$^2$/V$^2$. We also demonstrate electric-field driven dopant ionization in the SOI device layer, measured by electron spin resonance.Comment: 5 pages, 3 figure

Spin-dependent scattering in a silicon transistor

The scattering of conduction electrons off neutral donors depends sensitively on the relative orientation of their spin states. We present a theory of spin-dependent scattering in the two dimensional electron gas (2DEG) of field effect transistors. Our theory shows that the scattering mechanism is dominated by virtual transitions to negatively ionized donor levels. This effect translates into a source-drain current that always gets reduced when donor spins are at resonance with a strong microwave field. We propose a model for donor impurities interacting with conduction electrons in a silicon transistor, and compare our explicit numerical calculations to electrically detected magnetic resonance (EDMR) experiments. Remarkably, we show that EDMR is optimal for donors placed into a sweet spot located at a narrow depth window quite far from the 2DEG interface. This allows significant optimization of spin signal intensity for the minimal number of donors placed into the sweet spot, enabling the development of single spin readout devices. Our theory reveals an interesting dependence on conduction electron spin polarization p_c. As p_c increases upon spin injection, the EDMR amplitude first increases as p_{c}^{2}, and then saturates when a polarization threshold p_T is reached. These results show that it is possible to use EDMR as an in-situ probe of carrier spin polarization in silicon and other materials with weak spin-orbit coupling