Vincent Odhiambo Oketch

Doctor of Philosophy in Physics

1. Dr. George S Manyali
2. Prof. Thomas W Sakwa
3. Dr. Jared O. Odhiambo

ABSTRACT

Semiconductors have drawn massive attention due to their extraordinary properties and their applications in electronic and optoelectronic devices. Beryllium chalcogenides which are semiconductors are technologically significant because they can be used in the manufacture of among others, light-emitting devices that are employed in optical dispensation, detection systems for environmental pollution and color-displaying modules. There has also been an increasing interest in the study of these materials under high-pressure conditions, driven by the need of synthesizing new solids with targeted physical properties. An ab initio study will be undertaken to determine the structural, electronic, optical and elastic properties of beryllium chalcogenides. All calculations will be done based on Density Functional Theory (DFT) framework and a plane wave basis set as implemented in the QUANTUM ESPRESSO computer code. A comparison with previous work on DFT and experimental work will also be done. The projector Augmented Wave pseudopotential will be used to describe core valence electron interactions within the GGA (PBE, PBEsol, PW91,revPBE WC) and LDA chosen as the exchange correlations. This work will focus on these properties at ambient pressure to an elevated value in order to investigate the variations of these physical properties with respect to applied pressure. The study seek to bridge the gap between computational and the experimental results which still show a discrepancy in their findings.