Sub-micron, Metal Gate, High-к Dielectric, Implant-free, Enhancement-mode III-V MOSFETs

The performance of 300nm, 500nm and 1μm metal gate, implant free, enhancement mode III-V MOSFETs are reported. Devices are realised using a 10nm MBE grown Ga2O3/(GaxGd1-x)2O3 high-κ (κ=20) dielectric stack grown upon a δ-doped AlGaAs/InGaAs/AlGaAs/GaAs heterostructure. Enhancement mode operation is maintained across the three reported gate lengths with a reduction in threshold voltage from 0.26 V to 0.08 V as the gate dimension is reduced from 1 μm to 300 nm. An increase in transconductance is also observed with reduced gate dimension. Maximum drain current of 420 μA/μm and extrinsic transconductance of 400 µS/µm are obtained from these devices. Gate leakage current of less than 100pA and subthreshold slope of 90 mV/decade were obtained for all gate lengths. These are believed to be the highest performance submicron enhancement mode III-V MOSFETs reported to date

Enhancement Mode n-MOSFET with High-κ Dielectric on GaAs Substrate

In this paper, we report MOS heterostructures grown by molecular beam epitaxy on III-V substrates, employing a high-κ dielectric stack comprised of gallium oxide and gadolinium gallium oxide. Mobilities exceeding 12,000 and 6,000 cm2/Vs, for sheet carrier concentration ns of about 2.5x1012 cm-2 were measured on MOSFET structures on InP and GaAs substrates, respectively. These structures were designed for enhancement mode operation and include a 10 nm thick strained InGa1-xAs channel layer with In mole fraction x of 0.3 and 0.75 on GaAs and InP substrates, respectively

High Mobility III-V MOSFETs For RF and Digital Applications

Developments over the last 15 years in the areas of materials and devices have finally delivered competitive III-V MOSFETs with high mobility channels. This paper briefly reviews the above developments, discusses properties of the GdGaO/Ga2O3 MOS systems, presents GaAs MOSFET DC and RF data, and concludes with an outlook for high indium content channel MOSFETs. GaAs based MOSFETs are potentially suitable for RF power amplification, switching, and front-end integration in mobile and wireless applications while MOSFETs with high indium content channels are of interest for future CMOS applications

KEYWORDS Pod integrity Sterilization Cocoa beans Ochratoxin A Contamination

ABSTRACT To investigate the effects of pod integrity, pod surface contamination and effective bean drying on the level of Ochratoxin A contamination in dried cocoa beans from Ghana, ripe cocoa pods were harvested at Akim Tafo (Eastern Region) and sorted into four groups: healthy pods, diseased pods, diseased and damaged pods and damaged/broken pods. Each group was subjected to three main recommended fermentation systems, i.e. traditional heap, tray and box. Some of the treatments were replicated in two other ecological zones in Ghana where cocoa is produced viz Assin-Worakese (Central Region) and Wantram (Western Region). Fermented beans were dried in the open sun for a minimum period of nine days during which samples were taken for quantitative analysis of the level of Ochratoxin A using commercially available kit from Helica Biosystem Inc. Ochratoxin A contamination appear to be associated with the integrity (intactness) of the pods from which they were obtained, duration and conditions of drying, farm to farm practices and season of primary processing. Beans obtained from diseased pods and damage/broken pods gave the highest Ochratoxin A levels. None of the levels detected was however in the range considered by the European Union as inimical to human health. Ghana Cocoa Board recommendation to farmers is that damaged and diseased pods should not be fermented with wholesome pods, and that beans should be dried to completion in maximum of seven days. The study shows that if these conditions are adhered to, contamination of Ghana's Cocoa beans by Ochratoxin A can be entirely prevented

Next generation sequencing elucidates cacao badnavirus diversity and reveals the existence of more than ten viral species

Cacao swollen shoot virus is a member of the family Caulimoviridae, genus Badnavirus and is naturally transmitted to Theobroma cacao (L.) by several mealybug species. CSSV populations in West African countries are highly variable and genetically structured into several different groups based on the diversity in the first part of ORF3 which encodes the movement protein. To unravel the extent of isolate diversity and address the problems of low titer and mixed viral sequences in samples, we used Illumina MiSeq and HiSeq technology. We were able to reconstruct de novo 20 new complete genomes from cacao samples collected in the Cocoa Research Institute of Ghana (CRIG) Museum and from the field samples collected in Côte d'Ivoire or Ghana. Based on the 20% threshold of nucleotide divergence in the reverse transcriptase/ribonuclease H (RT/RNase H) region which denotes species demarcation, we conclude to the existence of seven new species associated with the cacao swollen shoot disease. These new species along with the three already described leads to ten, the total number of the complex of viral species associated with the disease. A sample from Sri Lanka exhibiting similar leaf symptomology to West African CSSD-affected plants was also included in the study and the corresponding sequence represents the genome of a new virus named cacao bacilliform SriLanka virus (CBSLV). [Abstract copyright: Copyright © 2017. Published by Elsevier B.V.

Knowledge Transfer Practices: A Means of Sustainable Career Development Among Non-Academic Senior Members in Ghana

The goal of this article is to look into how knowledge transfer practices might help non-academic senior members in Ghana maintain their career progress. The research was founded on interpretive philosophical assumptions, and a multiple case study design was employed to gain a comprehensive understanding of knowledge transfer methods among non-academic senior members of Ghanaian universities. Non-academic senior members of the Kwame Nkrumah University of Science and Technology (KNUST) and University of Cape Coast (UCC) and University of Ghana (UG) make up the study's population. The non-academic senior members of the study were chosen from fifteen (15) colleges within the institutions, and data was acquired through semi-structured interviews. The data was analyzed using thematic analysis. The results show that face-to-face interaction, after-action reviews, discussion forums, documentation, workshops, brainstorming and seminars were the most common methods for knowledge transfer. Non-academic senior members benefit from this type of information transfer in their career paths and development. Institutions should build up a knowledge portal where personnel may readily access material from other units or sections within their context, according to the recommendations