Calculation Of Full-band Electronic Structure In Semiconductor Resonant Tunneling And Zero-dimensional System

With unique physical properties semiconductor low-dimensional structures promote the development of next-generation semiconductor devices. Due to the potential application in spin electronics and quantum computing, semiconductor resonant tunneling and zero-dimensional quantum dot system have been widespread attention in recent years. We investigate two kinds of low-dimensional semiconductor systems by full-band kp method, one-dimensional resonant tunneling diode (RTD) and zero-dimensional quantum dot (QD).We mainly study the dependence of tunneling properties on the interface charge in the GaN RTD. Moreover we campare single-band method with the full-band one in the calculation of band structure of InxGa1-xAs pyramidal quantum dot. On this basis, using the full-band method we have studied the dependence of QDs'energy level and Zeeman splitting energy on the size and alloy of the QDs, and explored that the spin splitting energy of the QD system can be non-linear variation in high magnetic field. The results are very useful to actual manufacture of low-dimensional semiconductor devices. The paper mainly contains the following works:Firstly, we have investigated the dependence of tunneling properties on the interface charge in GaN resonant tunneling diode (RTD) by the nonequilibrium Green's function method. In Al0.15Ga0.85N/GaN/Al0.15Ga0.85N resonant tunneling structures, resonant levels and resonant peaks increase with the increasing concentrations of the interface charge. Compared to the positive charge, the negative charge in the right sides of the quantum well makes greater impact on the tunneling properties. Furthermore, the peak valley ratio (PVR) ofⅠ-Ⅴcurve can have optimum value in a certain concentration range.Secondly, we use the single-band and the full-band model to analyze the electronic structure of pyramidal QD in detail. The results show that:the results of single-band and full-band model are quite different. Due to the strong coupling between the conduction band and valence band, the light hole energy and heavy one, the full-band method could well reflect the objective physical laws in the low-dimensional structure, especially in the narrow band gap semiconductor.Thirdly,by the full-band method we have explored the spin energy level properties of the pyramidal QD in variable magnetic field. Without magnetic field, the size of QDs can have an effect on the electron and hole energy levels. In low magnetic field, width, height and alloy were changed in a certain range, the value of g factor will change correspondly.The g factor is 0 in certain conditions, while the corresponding system has changed from negative polarization to no polarization to positive polarization. Meanwhile, the value of the g factor can be strongly influenced by the proportion of the hole Bloch state in conduction band(the orbit component is introduced in conduction band),while the spin-orbit coupling can explain the variation of the g factor. In high magnetic field, theΔE of QDs with small size is linear variation, while the large size one has significant non-linear trend. A preliminary analysis is provided about the physical mechanism of this non-linear change.