Increasing the bit density from a quantum-confinement physically unclonable function

This dissertation presents work carried out in collaboration with the IMDEA nanoscience institute. We study the recently proposed quantum confinement physically unclonable function by Roberts, et al. that utilises resonant tunnelling diodes (physical representation of a quantum well) and atomic scale imperfections for applications in cryptography and identification. Presently such entities rely on their resonance peak position as the basis for a new approach to electronic identification systems.By solely relying on the resonance peak of these devices deconvolution outputs an average of 8 bits per device, concatenation of up to 16 devices outputs a satisfactory number of bits for applications in uniqueness. However we explore the possibility of increasing the bit density of such physically unclonable functions that range from tangibly modifying the heterostructure with the use of a focused ion beam to induce quantum effects of 1 dimension (quantum wire) and 0 dimension (quantum dot) that would manifest its self as multiple resonance peaks observed on the current/voltage characteristic.Our findings show multiple devices with consistent new features as a result of modification with the focused ion beam ultimately increasing the bit density. We carry out cryogenic measurements and comment on the fact that such features are not supported by previous work studying resonant tunnelling in the 1 & 0 states of double barrier heterostructures.