Abstract

Few-layer black phosphorus (FLBP) is characterised by a tuneable bandgap, high carrier mobility and anisotropic optical properties. It therefore has the potential to find applications in electronics and photonics. FLBP oxidizes upon exposure to air, limiting its utility in devices and components. To address this issue, the thesis introduces methods and tools developed for studying FLBP's optical parameters, with a particular emphasis on its potential for sensing applications. Spectroscopic ellipsometry and polarisation microscopy were utilised to characterise the optical properties of multilayer black phosphorus in relation to its degradation processes and optical anisotropy. The dissertation also employed photoluminescence and electrochemistry techniques for the characterization and evaluation of the black phosphorus-based sensor for metal ion detection. Ellipsometry was used to determine the refractive index and extinction coefficient of FLBP, demonstrating that separating and centrifuging the bulk material can yield a layer with optical parameters closely resembling those of a two-dimensional material. Polarizing microscopy studies made it possible to determine the kinetics of the black phosphorus oxidation process, thereby revealing how it modifies the polarization parameters. Polarizing microscopy studies made it possible to determine the kinetics of the black phosphorus oxidation process, which modifies the polarization parameters. For the sensor design, FLBP was combined with zinc oxide, firstly to increase the resistance of black phosphorus to degradation by oxidation, and secondly to shift the photoluminescence response of the sensor into the visible region. This approach allowed the use of silicon detector in the photoluminescent sensor, enabling the detection of zinc and magnesium ions at lower concentrations than those detected by standard solutions.

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