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This study is focused on the investigation of SnS thin film for transistor application. Electron trap which is associated with grain boundary effect affects the electrical conductivity of SnS semiconductor thin film thereby militating the attainment of the threshold voltage required for transistor operation. Grain size and grain boundary is a function of a semiconductor’s thickness. SnS semiconductor thin films of 0.20, 0.25, 0.30, 0.35, 0.40 μm were deposited using aerosol assisted chemical vapour deposition on glass substrates. Profilometry, Scanning electron microscope, Energy dispersive X-ray spectroscopy and hall measurement were used to characterise the composition, microstructure and electrical properties of the SnS thin film.  SnS thin films were found to consist of Sn and S elements whose composition varied with increase in thickness. The film conductivity was found to vary with grain size and grain boundary which is a function of the film thickness. The SnS film of 0.4 μm thickness shows optimal grain growth with a grain size of 130.31 nm signifying an optimum for the as deposited SnS films as the larger grains reduces the number of grain boundaries and charge trap density which allows charge carriers to move freely in the lattice thereby causing a reduction in resistivity and increase in conductivity of the films which is essential in obtaining the threshold voltage for a transistor semiconductor channel layer operation. The carrier concentration of due to low resistivity of 3.612 ×105 Ωcm of 0.4 μm SnS thin film thickness is optimum and favours the attainment of the threshold voltage for a field effect transistor operation hence the application of SnS thin film as a semiconductor channel layer in a field effect transistor.

High quality reduced graphene oxide (RGO) nanosheets were prepared from natural graphite using an improved modified Hummers method. The morphological, structural and electrochemical properties of the RGO were characterised by scanning electron microscope (SEM), Raman spectroscopy, X-ray diffraction (XRD) analysis, Cyclic Voltammetry (CV) analysis and Electrochemical Impedance Spectroscopy (EIS) analysis. The SEM image of the RGO showed that, there was a small increase in the number of grain boundaries, indicating a collapse of the surface coalescence of the graphene oxide. The XRD peak at 24.56˚ corresponds to the (002) diffraction plane with the interlayer spacing along the c-axis of 2.0989 Ǻ. The Raman shift for the reduced graphene oxide gives the ID/IG intensity ratio of 1.04. The RGO exhibited good electrochemical characteristics with energy density and power density of 19.2 Whkg -1 and 149.3 Wkg -1 respectively.

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The disordered electron-hole recombination in multi-quantum well was investigated using analytical method based on the rate equations. The results show extreme broad distribution of the recombination time which depends exponentially on the distances between the recombining excitons. The energies at each localised state shows an energy splitting between the electronic ground state and the first excited state of 0.0038eV.