Abstract
part1: With the development of technological industry in recent twenty years, the demand for high- speed device get more day by day. Compound semiconductors which are such as Light Emission Diode (LED), and high power electronic device for example: High-Electron Mobility Transistor (HEMT), Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) played an important role. We focus on research about GaN MOS diode and fabricate (Ga2O3)Gd2O3/GaN by using ultra high vacuum molecular beam epitaxy (UHV-MBE).We take advantage of X-ray reflectivity (XRR) and High-resolution transmission electron microscopy (TEM) to make sure that interface was abrupt and had less roughness. Using capacitance-voltage(C-V), current-voltage(I-V) curve to understand that (Ga2O3)Gd2O3 dielectric constant κ was almost 15, interfacial state(Dit) around 1012cm-2eV-1 by using Terman method and leakage current around 10-8A/cm2 at 1MV/cm.On the other hand, we make use of atom layer deposition(ALD) to grow HfO2 on GaN,and take X-ray reflectivity (XRR) and High-resolution transmission electron microscopy (TEM) to realize that surface roughness was roughly 0.4nm.From C-V curve, we know that dielectric constant κ value was almost 15, interfacial state (Dit) around 1012cm-2eV-1 and leakage current was around 10-8A/cm2 at 1MV/cm.We found (Ga2O3)Gd2O3 and HfO2 unpin the GaN Fermi level so that they have great contribution for depletion-mode and enhancement-mode GaN MOSFET and MOS-HEMT. part2: Spin electronics, or spintronics, is a nascent field of research whereby the spin degree of freedom in electronic devices is exercised. The electroluminescence (EL) polarization of the spin light emission diode (spin-LED) is important in the characterization of spin injection efficiency into non-magnetic semiconductor. We use optical instruments to distinguish the left and right circular polarized light and find out its relative spin polarization. The Fe3Si/GaAs(001) hybrid structure with high crystalline and interfacial quality have been fabricated in my group by using ultra-high vaccum molecular-beam epitaxy system(UHV-MBE) with base pressure under 10-10 torr. The Fe3Si is regarded as half metal with 100﹪spin polarized at the Fermi level, hence making Fe3Si an attractive material for electric spin injection. Spin injection into GaAs from Fe3Si, spin aligning contact, via a Schottky barrier was measured. The spin polarization was roughly zero at room temperature and externally magnetic field of 0.1 tesla. In order to increase the polarization scales, we will measure the LED with Fe3Si in low temperature and highly externally magnetic field to decrease thermal disturbance and increase demagnetization respectively in the future.