Adoption of artificial intelligence based technologies in sub-saharan african agriculture

Dissertation presented as the partial requirement for obtaining a Master's degree in Information Management, specialization in Knowledge Management and Business IntelligenceSub-Saharan Africa (SSA) is currently facing numerous agriculture related challenges such as climate change, lacking infrastructure, and limited institutional as well as economic support. However, current research does not provide holistic solutions to this problem. This study aims to shed light on this topic through the development of a model that can be used to assess the solution potential as well as high-level implementation requirements of selected artificial intelligence (AI) based agriculture technologies in the context of SSA. To thoroughly develop the above-mentioned model a design science approach was followed. First an in depth (systematic) literature review was conducted where the agriculture related challenges in SSA and state-of-the-art AI-based agriculture technologies are detailed. This step was followed by the creation of a model that aims to find a nexus between the researched challenges and available technologies as potential solutions. Furthermore, the framework outlines context specific technology adoption requirements. Lastly, expert interviews were conducted to validate and revise the proposed model. The final framework clearly highlights the positive impact AI based technologies can have in SSA’s agriculture and the basic conditions that need to be met to successfully implement them

Position controlled self-catalyzed growth of GaAs nanowires by molecular beam epitaxy

GaAs nanowires are grown by molecular beam epitaxy using a self-catalyzed, Ga-assisted growth technique. Position control is achieved by nano-patterning a SiO2 layer with arrays of holes with a hole diameter of 85 nm and a hole pitch varying between 200 nm and 2 \mum. Gallium droplets form preferentially at the etched holes acting as catalyst for the nanowire growth. The nanowires have hexagonal cross-sections with {110} side facets and crystallize predominantly in zincblende. The interdistance dependence of the nanowire growth rate indicates a change of the III/V ratio towards As-rich conditions for large hole distances inhibiting NW growth.Comment: 9 pages, 4 figure

Direct detection of spontaneous polarization in Wurtzite GaAs nanowires

We demonstrate the direct detection of spontaneous polarization in the wurtzite crystal phase of gallium-arsenide (GaAs) nanowires. Using differential phase contrast microscopy (DPC) in a scanning transmission electron microscope, we map the differences in charge distribution between the zinc-blende and wurtzite crystal phases and use twin defects in the zinc-blende phase to quantify the polarization strength. The value of 2.7 × 10−3 C/m2 found for the polarization strength matches well with theoretical predictions

Long exciton in stacking-fault-free wurtztite GaAs nanowires

We present a combined photoluminescence and transmission electron microscopy study of single GaAs nanowires. Each wire was characterized both in microscopy and spectroscopy, allowing a direct correlation of the optical and the structural properties. By tuning the growth parameters, the nanowire crystal structure is optimized from a highly mixed zincblende–wurtzite structure to pure wurtzite. We find the latter one to be stacking-fault-free over nanowire lengths up to 4.1 μm. We observe the emission of purely wurtzite nanowires to occur only with polarization directions perpendicular to the wurtzite cˆ -axis, as expected from the hexagonal unit cell symmetry. The free exciton recombination energy in the wurtzite structure is 1.518 eV at 5 K with a narrow linewidth of 4 meV. Most notably, these pure wurtzite nanowires display long carrier recombination lifetimes of up to 11.2 ns, exceeding reported lifetimes in bulk GaAs and state-of-the-art 2D GaAs/AlGaAs heterostructures

Epitaxial Growth of Room-Temperature Ferromagnetic MnAs Segments on GaAs Nanowires via Sequential Crystallization

We investigate the incorporation of manganese into self-catalyzed GaAs nanowires grown in molecular beam epitaxy. Our study reveals that Mn accumulates in the liquid Ga droplet and that no significant incorporation into the nanowire is observed. Using a sequential crystallization of the droplet, we then demonstrate a deterministic and epitaxial growth of MnAs segments at the nanowire tip. This technique may allow the seamless integration of multiple room temperature ferromagnetic segments into GaAs nanowires with high-crystalline quality