Investigation of Negative Differential Resistance Phenomena in Quantum Well Heterostructures
Increasing interest in entirely new possibilities for quantum mechanical description of carriers transport is becoming more evident with the developing advancements in epitaxial growth technique. Consequently, molecular beam epitaxy (MBE) technique is considered to be the most precise technique that allows the growth of ultra-thin layers of different compositions. Those structures can be designed to investigate the wave-nature of carriers, which broadens the possibilities in device design and fabrication for a specific area. In this thesis the fundamental study of the real space charge transfer (RST) mechanism that took place in quantum well heterostructures and led to the negative differential resistance observation is presented. Using the Hall effect measurement technique, the mobility and carrier concentration were measured and analyzed by considering different scattering mechanisms and carrier thermal activation phenomena, respectively. Deep level noise spectroscopy (DLNS) was used to investigate and probe the materials for the presence of defects and impurity states, which were needed to achieve the RST. The pulsed I-V measurements were performed to observe the negative differential resistance (NDR). Finally, the lock-in technique and pulsed I-V technique with light excitation and temperature cycling were used to prove the presence of RST mechanism in our system. The results of this study can be implemented to create devices for high frequency applications.
Applied sciences, Pure sciences, Deep level noise spectroscopy (DLNS), Molecular beam epitaxy (MBE), Negative differential resistance (NDR), Quantam well, Real space charge transfer (RST), Other Physics, Quantum Physics, Structural Materials
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