Browsing by Author "Mnguni, Mmangaliso Mpilonde"

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    Isothermal and non-isothermal comparative study of zn-sn system using real-time rbs
    (University of the Western Cape, 2021) Mnguni, Mmangaliso Mpilonde; Kotsedi, Lebogang
    Insight into the effects of isothermal and non-isothermal annealing on bi-metallic thin film is important for material synthesis and application in everyday use. The effects of isothermal annealing on bi-metallic thin films has long been studied using various heating methods from a resistively heated filaments, by transferring heat via conduction, convection and irradiation. The effect of each method have been widely reported in literature. The diffusion coefficient and activation energies of the constituent atoms can calculated for each annealing method. On the other hand, the effects of non-isothermal annealing on bi-metallic thin films has not been comprehensively studied, and there are areas of this annealing regime that need further investigation. In this study a femtosecond laser with a 1064 nm central wavelength was used to anneal bi-metallic thin films of Zinc-Tin (Zn-Sn) on a substrate.
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    Isothermal and non-isothermal comparative study of Zn-sn system using real-time RBS
    (2021) Mnguni, Mmangaliso Mpilonde; Kotsedi, Lebogang
    Solid-state reactions of bi-metallic systems can be driven or activated by various external stimuli like pressure, energetic photons, energetic charged particles or heat. For an example, high pressure torsion can be applied to aluminium-copper (Al-Cu) to drive solid-state reaction [1.1]. Oh-ishi et al. [1.1] applied a pressure of 6 GPa to Al and Cu half discs. Following this, x-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM) were used to confirm the formation of different intermetallic phases such as Al2Cu and Al4Cu9. One of the first reported case where photons were used to drive solid phase diffusion was reported in 1998 by Ditchfield et al. [1.2]. The study was carried out to study the non-thermal effects of photons illumination on surface diffusion, an important process in microelectronics fabrication. Surface diffusion governs several important steps in microelectronics fabrication including the formation of hemispherical grained silicon used in memory devices [1.2], filling of channels with metals for devices interconnection purposes among others [1.2]. In this study, germanium-indium (Ge-In) on silicon was used because the thermal diffusion of this system was well understood [1.3]. Surface diffusion was measured in ultrahigh vacuum via second harmonic microscopy when the sample was illuminated with pulsed Nd: YAG laser at a wavelength of 1064 nm [1.3]. This study showed conclusively that photons could be used to drive solid-state reactions.