The Growth And Properties Of Tb-doped ZnO Films And High K Dielectric Er₂O₃ Films

Two parts are included in this dissertation: The growth and properties of Tb-doped ZnO films and high k dielectric Er₂O₃ filmsZinc oxide (ZnO) are one of very useful materials and are used in piezoelectric device, transparent electrodes in photovoltaic and display, and light-emitting diodes. In this dissertation, we report the influence of the post-treatment on the structural and optical properties of reactive sputtering ZnO films, and Preparation of transparent conductive ZnO:Tb films and their photoluminescence properties.Polycrystalline ZnO films were prepared by reactive radio frequency sputtering (RF) technique with zinc target in the mixed gas of Ar and O₂. The grain size increases with the annealing temperature. The photoluminescence (PL) spectra of these samples consist of one emission peak centered at 2.9 eV. This is first reported about the blue emission. It was proposed that the blue emission originated from the interstitial Zn.Tb-doped Zinc oxide (ZnO:Tb) films were prepared by RF reactive magnetron co-sputtering of a Zn target with some Tb-chips attached. The results show that the appropriate Tb ions incorporation into ZnO films can improve the structural and electrical properties of ZnO films. PL measurements show the characteristic emission lines corresponding to intra-4fⁿ-shell transitions of Tb. Under the optimal conditions, the ZnO:Tb films with the low resistivity (p), the high transmittance at the visible region and the strong blue emission were prepared.The industry's demand for higher integrated circuit density and performance has forced the gated dielectric layer thickness to decrease rapidly. The use of conventional SiO₂ films as gate oxide is reaching its limit. Therefore, a variety of alternative high-k materials are being investigated as possible replacements for SiO₂. It has been reported that Er₂O₃ may be one of the most promising alternative dielectrics. However, there are no reported about growth of single crystal and amorphous Er₂O₃. In this thesis, we have studied the growth and characterization of high k materials Er₂O₃.The epitaxial growth of Er₂O₃ films on Si(100) and Si(111) have been investigated.The epitaxial relationship between Er2C>3 and Si(100) substrate is as follows: Er2O3(110) // Si(100), or Er2O3(100) // Si(100). The epitaxial relationship between Er2(>3 and Si(lll) is Er2O3( 111 )//Si(111). The oxidized Si surface can suppress the formation of the silicide phase. By using x-ray photoelectron spectroscopy, the valence and the conduction band offset of Er2O3 to Si are obtained to be 3.1 ±0.1 eV and 3.5±0.3 eV, respectively. And the energy gap of Er2C>3 is determined to be 7.6±0.3 eV. Up now, we first reported the data about the band gap of Er2O3 and its band offsets to Si.Stoichiometric, amorphous, uniform Er2C>3 films are deposited on Si (001) substrates by reactive evaporation using metallic Er source at room temperature in an oxygen ambient pressure of 9x10"6 Torr. TEM measurement shows the films good thermal stability and a sharp interface after annealing at 700 °C for 30 minutes in ultrahigh vacuum (UHV). An effective relative dielectric constant is 12.6, an effective oxide thickness (EOT) of 1.4 nm is achieved, with a low leakage current density of 8x10"* A/cm2at electric field of 1 MV/cm and a fixed charge density of 3*1012 cm"2 after annealing. The obtained characteristics indicate that the ultrathin amorphous Er2C>3 film could be a promising candidate for high k gate dielectric.