Development of advanced atomic force microscopy methods for nanoscale semiconductor characterization

Disorder and local electrostatics play a central role in determining the electronic behaviour of amorphous and molecular semiconductors. In these systems, the absence of long-range order leads to spatial fluctuations of the electrostatic potential and to broad distributions of localized states, which critically affect charge injection, transport, and recombination. Conventional electrical and optical characterization techniques probe macroscopic averages and therefore fail to capture the microscopic inhomogeneities that dominate device operation at the nanoscale. This thesis investigates how microscopic disorder and local electrostatic phenomena govern the electronic response of disordered semiconductors, with a particular focus on amorphous oxide thin films and organic heterostructures. Scanning probe microscopy techniques are employed to access local electronic properties with nanometric resolution. Kelvin Probe Force Microscopy is used to quantitatively determine band tail parameters, doping density, and flat-band conditions in amorphous oxide semiconductors, supported by analytical modelling of band bending in finite-thickness films. Lateral and electrostatic force microscopy methods are further developed to probe charge diffusion, capacitive coupling, and spatial broadening of optoelectronic excitation in organic planar heterojunctions. By combining local photovoltage mapping, transient measurements, and electrostatic modelling, the work establishes a direct link between carrier lifetime, mobility, and the effective diffusion length that limits spatial resolution in optoelectronic devices. The results show that material choices and interfacial engineering can trade efficiency for spatial confinement, defining intrinsic resolution limits even in unpatterned devices. Finally, the implications of these findings are discussed in the context of high-resolution optobioelectronic interfaces and thin-film devices, where controlling local electrostatics is essential to achieve predictable and scalable functionality.