| Tow parts are included in this dissertation:1. The growth and properties of high k dielectric La2Hf2O7 and Hf(1-x)LaxOy films.The industry's demand for greater integrated circuit functionality and performance at lower cost requires an increased circuit density. As the most important electronic device, the size of metal-oxide-semiconductor field effect transistor (MOSFET) has been shrinking according to Moore's Law of scaling over forty years. According to the International Technology Roadmap for Semiconductors (ITRS), the continuous downscaling will be applied at least for one more decade. With the continuous down scaling, the thickness of conventional SiO2 gate dielectric will be thinner than lnm. This will increase the leakage current exponentially due to quantum mechanical tunneling, and seriously affects the performance of device. Therefore, it is necessary to replace the SiO2 with a new high k gate material, which can increase the thickness while maintaining the gate capacitance, potentially reducing the tunneling current. Among the various high-k dielectric materials, Hf-based dielectrics and rare earth oxides have been regarded as the most promising candidates. However, the basic study of physical properties is still lacking, such as interface, band offset, the nature and origin of their large dielectric constant. In this study, we choose the Hf-based gate dielectric and La2O3 as the materials of our research, using Pulsed Laser Deposition (PLD) technique to grow the La2Hf2O7 and Hf(1-x)LaxOy films. Different kinds of characterization methods are applied to investigate their microstructure, thermal stability, interfacial reaction and phonon modes.First, amorphous La2Hf2O7 films were deposited on Si (100) substrates by PLD method. La2Hf2O7 films show excellent thermal stability. The films can keep amorphous even after 900℃thermal anneal, which meet the requirement of semiconductor technology. The results of EXAFS show that the local structure of amorphous film is similar with that La2Hf2O7. The interface structure is systematically studied by combining XRR, XPS and FTIR methods. Silicate and SiOx formation from interfacial reaction are observed in the interfacial layers during deposition. With higher temperature or longer deposition time, the interfacial layers become thicker. A few of Hf-silicide microcrystals have been formed during vacuum grown condition, which is detrimental to the electric property. Our result shows that Hf-silicide can be effectively eliminated by growing in oxygen ambience or post deposition annealing, which evidently improves the electric property. By using SR-XPS, the valence band offset (△Ev) of La2Hf2O7 film to Si is determined to be 2.6±0.1eV. According to the reference, it is reported that the band gap of La2Hf2O7 is 5.6eV. Its conduction band offset (△Ec) with 1.7±0.1eV is obtained, which can satisfy the requirements of high k dielectrics. Far Infrared spectroscopy is applied to study the optical phonon modes and dielectric constants of La2Hf2O7 material and thin films. We discuss the contribution of every phonon mode to dielectric constant. The thin film can keep main infrared phonon modes, but the lost and weakness of some soft phonon modes causes the dielectric constant of film smaller than that of bulk material.Furthermore, HfO2 and Hf (1-x)LaxOy dielectric films are grown on Si(100) by PLD method. The effect of growth condition and La doping concentration on the film structure, infrared vibrational modes and dielectric property has been investigated. HfO2 films deposited at room temperature and 400℃are amorphous and monoclinic, respectively. Some far infrared phonon modes disappear due to the structure disorder and crystalline quality of thin film, which causes the dielectric constant of thin film smaller than that of bulk sample. However, main infrared phonon modes are preserved and the film still has enough value of dielectric constant. Lanthanum serves effectively as a dopant to induce a phase transformation from the monoclinic to the cubic phase even at 700℃, which shows higher permittivity than undoped HfO2. However, the introduction of more Lanthanum into HfO2 will cause an increase of crystallization temperature and form the amorphous films. With more La introduction, the main phonon mode is softened and higher permittivity is obtained. These results are useful for its application and search of new high-k dielectrics.2. Study of the luminescent properties and mechanism of the white-light long afterglow phosphors:CaxMgSi2O5+x:Dy3+(x=1,2,3).Colours of the developed long-lasting phosphors range from bule to red. Unfortunately, no phosphor with white-light long afterglow has been developed into a commercial application so far. Therefore, search of a better white-light long afterglow phosphor becomes a new research area. Because of their predominant chemical stability and thermal stability, calcium magnesium silicates are a kind of important host materials for long afterglow phosphors. Therefore, we prepare and investigate a series of Dy3+-doped calcium magnesium silicate phosphors—CaxMgSi2O5+x:Dy3+(x= 1,2,3). The white-light emission originates from the combination of the 475nm blue emission and the 575nm yellow emission, corresponding to the 4F9/2→6H15/2 and 4F9/2(?)→>6H13/2 transitions. The white-light afterglow can last about more than one hour in darkness for most of our samples. The afterglow decay curves and the thermoluminescence spectra are employed to discuss the origin of the traps and the mechanism of the afterglow emission.
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