Ndlovu, Gebhu Freedom, Hillie, K. T., Roos, W. D., Ndlovu, Gebhu Freedom, Hillie, K. T., and Roos, W. D.
English: The thesis deals with adsorption, self–assembly and surface reactions of Sb atoms on solid Cu(111) substrates. It is of genuine interest in materials science and technology to develop strategies and methods for reproducible growth of extended atomic and molecular assemblies with specific and desired chemical, physical and functional properties. When the mechanisms controlling the self-organized phenomena are fully disclosed, the self-organized growth processes can be steered to create a wide range of surface nanostructures from metallic, semiconducting and molecular materials. The experimental technique used to study ordered phases and phase transitions of Sb on Cu(111) substrates was the Scanning Tunneling Microscopy (STM) – an outstanding method to gain real space information of the atomic scale realm of adsorbates on crystalline surfaces. It is a general trend to conduct studies on well known structures before one begins working on complicated systems. Therefore, in this study, Si(111) Cu(111) and HOPG surfaces were studied in atomic detail to confirm the calibration and the resolution capabilities of the instrument. The acquired data were comparable to the reported theoretical and experimental data in literature. The investigated Cu(111) – Sb system is characterized by a complex interplay between adsorbate interactions and adsorbate substrate interactions which in this study manifests through self–assembly processes. Both low energy electron diffraction (LEED) and Auger electron spectroscopy (AES) were utilized to determine the substrate cleanliness prior to the growth of a submonolayer Sb coverage (0.43 ± 0.02 ML Sb as calculated from the acquired STM data). The freely diffusing Sb adatoms on the copper surface were thermally excited from a random distribution of Sb atoms after growth to a finally rearrangement to more energetically stable configuration. The experimental results illustrated the presence of a surface alloy after annealing at ~360°C. The, Afrikaans: Die proefskrif handel oor die adsorpsie, selfrangskikking en oppervlakreaksie van Sb atome op ‘n soliede Cu(111) substraat. In die materiaalwetenskap en tegnologie is dit belangrik om strategieë en metodes te ontwikkel wat die reproduserende groei van ingewikkelde atomiese en molekulêre strukture, met spesifieke voorafbeplande chemiese, fisiese en funksionele eienskappe, vestig. Indien die meganismes, verantwoordelik vir die verskynsel van selfrangskikking, verstaan word, kan hierdie groeiprosesse gemanipuleer word om ‘n wye reeks nanostrukture op die oppervlak van metale, halfgeleiers en molekulêre materiale te bewerkstellig. In hierdie ondersoek oor geordende fases en fase oorgange van Sb op ‘n Cu(111) substraat, is die Skandeertonnelmikroskoop (STM) as eksperimentele tegniek gebruik. Dit is ‘n besonderse metode om inligting, op die atomiese vlak en in werklike ruimte, van ‘n geadsorbeerde stof op kristallyne oppervlakke te verkry. Dit is algemeen dat ondersoeke van hierdie aard eers op welbekende strukture gedoen word, voordat met meer komplekse studies begin word. In hierdie ondersoek is die Si(111), Cu(111) en HOPG oppervlakke op ‘n atomiese vlak ondersoek om die herhaalbaarheid, kalibrasie en oplosvermoë van die instrument te bevestig. Die gemete data was dan ook vergelykbaar met die gerapporteerde, teoretiese en eksperimentele, data in die literatuur. Die Cu(111) – Sb sisteem wat ondersoek is, is gekenmerk deur ‘n komplekse wisselwerking van reaksies tussen die adsorbate en ook tussen die geadsorbeerde stof en die substraat, wat manifesteer in selfrangskikkings prosesse. Beide lae-energieelektrondiffraksie (LEED) en Augerelektronspektroskopie (AES) is gebruik om die suiwerheid van die substraat te bepaal alvorens ‘n sub-monolaag Sb bedekking (0.43 ± 0.02 ML Sb soos bereken vanaf die STM data) gedeponeer is. Die geadsorbeerde Sb atome het willekeurige posisies op die oppervlak ingeneem, waarna dit termies gestimuleer is om na energeties meer stabiel, Council for Scientific and Industrial Research (CSIR), Department of Science and Technology (DST), National Research Foundation (NRF)