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Title: Dimensionality transitions in group III-V semiconductors
Author: Zhu, G.
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2016
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Since their conception two centuries ago, semiconductors have rapidly become one of the most active fields of research. As their exceptional potential became recognised, increasing amounts of resources were invested in the research and production of these materials. Consequently, semiconductor industry has gradually grown to become an essential lifeline of world economics. In the early 1980, the demand for electronic device miniaturisation, high integration and high computing speed led to the emergence of mesoscopic physics. Meanwhile, advances in materials science and microprocessing technology enabled experimental study in this area. By constantly reducing the scale of semiconductor devices, manufacturers could integrate smaller electronic devices onto one chip. These so-called integrated circuits perform storage, computing and other functions. In current production lines of the semiconductor industry, nanoscale electronic components have become the conventional technology. This thesis investigates transport properties of two-dimensional electrons using the phenomenon of magnetoresistance in perpendicular magnetic fields at low temperature. Dimensionality transitions are enabled by quantum point contact. Chapter 1 and 2 introduce the background information and low dimensional transport related theories, respectively. Chapter 3 describes the sample fabrication technique, instruments used in our experiments and the experimental set-up. Low-temperature measurements of the split-gate GaAs/AlGaAs heterostructure are fully described in Chapter 4. The phase-coherence information is extracted by investigating the weak localisation effect at various temperature. The temperature dependence of phase coherence experimentally reflects the underlying transport properties. Chapter 5 investigates and discusses the universal conductance fluctuation. The InGaAs/InAlAs heterostructure using which we interpret the lowtemperature transport phenomena, is experimentally investigated in Chapter 6.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available