Excited states and quantum confinement in room temperature few nanometre scale silicon single electron transistors.

Single nanometre scale quantum dots (QDs) have significant potential for many 'beyond CMOS' nanoelectronics and quantum computation applications. The fabrication and measurement of few nanometre silicon point-contact QD single-electron transistors are reported, which both operate at room temperature (RT) and are fabricated using standard processes. By combining thin silicon-on-insulator wafers, specific device geometry, and controlled oxidation, <10 nm nanoscale point-contact channels are defined. In this limit of the point-contact approach, ultra-small, few nanometre scale QDs are formed, enabling RT measurement of the full QD characteristics, including excited states to be made. A remarkably large QD electron addition energy ∼0.8 eV, and a quantum confinement energy ∼0.3 eV, are observed, implying a QD only ∼1.6 nm in size. In measurements of 19 RT devices, the extracted QD radius lies within a narrow band, from 0.8 to 2.35 nm, emphasising the single-nanometre scale of the QDs. These results demonstrate that with careful control, 'beyond CMOS' RT QD transistors can be produced using current 'conventional' semiconductor device fabrication techniques.

Evaluation of Kumaon hill goats for resistance to natural infection with gastrointestinal nematodes.

The present study deals with the investigation of different degrees of genetic resistance/resilience of Uttarakhand hill goats to natural infection with gastrointestinal nematodes in order to introduce into breeding schemes. Animals were naturally infected with Haemonchus contortus, Teladorsagia circumcincta, Oesophagostomum spp. and Trichostrongylus spp. Faecal egg counts (FEC) were carried out every month for a period of 1 year and blood samples were collected every third month for the determination of indicator traits such as FEC, packed cell volume (PCV) and haemoglobin (Hb). The mean egg per gram (EPG), PCV and Hb were 1,579.6 ± 346, 35.12 ± 1.1 and 8.7 ± 0.2, respectively. The goats were divided into three groups (<800, 801-2,000 and >2,000) based on EPG. The EPG showed a negative correlation with both Hb and PCV (P < 0.01). Therefore, it was concluded that the Hb and PCV value would decrease, if EPG increases.

Single-electron and quantum confinement limits in length-scaled silicon nanowires.

Quantum-effects will play an important role in both future CMOS and 'beyond CMOS' technologies. By comparing single-electron transistors formed in un-patterned, uniform-width silicon nanowire (SiNW) devices with core widths from ∼5-40 nm, and gated lengths of 1 µm and ∼50 nm, we show conditions under which these effects become significant. Coulomb blockade drain-source current-voltage characteristics, and single-electron current oscillations with gate voltage have been observed at room temperature. Detailed electrical characteristics have been measured from 8-300 K. We show that while shortening the nanowire gate length to 50 nm reduces the likelihood of quantum dots to only a few, it increases their influence on the electrical characteristics. This highlights explicitly both the significance of quantum effects for understanding the electrical performance of nominally 'classical' SiNW devices and also their potential for new quantum effect 'beyond CMOS' devices.