Zirconia films of varying thickness (ranging from 20–55 Å) have been grown by the method of UV ozone oxidation at room temperature. The electrical properties of these films have been studied in detail by capacitance–voltage (C–V) and I–V measurements. Capacitors were subjected to various anneals in differing ambient to study their effects on C–V hysteresis, dispersion and charge trapping. It was found that annealing in nitrogen followed by forming gas resulted in C–V curves with negligible hysteresis. The effects of different underlayers on the electrical properties of zirconia films have also been studied and are briefly discussed. It was found that zirconia films grown on UV-ozone grown SiO2 had lower hysteresis and lower interface trap density compared to zirconia films grown on chemical oxide. The effect of oxidation time and oxygen pressure have been investigated; in particular, detailed electrical studies have been performed on partially oxidized zirconia. Defective oxides are shown to have significant frequency dispersion in both the accumulation and depletion regions of the C–V curves along with very high loss tangent factor compared to stoichiometric oxides. A physical mechanism based on Maxwell–Wagner interfacial polarization is presented here for a model system of ZrO2–Zr to explain the experimental data qualitatively. Finally, we have attempted to correlate the C–V hysteresis to the presence of traps in the zirconia film using temperature-dependent current–voltage measurements. The leakage current was found to be nearly independent of temperature at low voltages, suggesting a tunneling mechanism, while at higher voltages the data can be modeled using the Poole–Frenkel conduction mechanism. It is suggested that C–V hysteresis in zirconia films possibly arises from electrical traps in the film and can be identified by modeling their I–V characteristics.

In this letter, we report on the growth of ultrathin films of zirconia on silicon oxide and silicon oxynitride passivated (001) Si by ultraviolet ozone oxidation of Zr metal precursor layers. The oxidation kinetics has been measured using an accelerator-based nuclear reaction analysis. It was found that oxide films up to 55 Å could be grown at room temperature by oxidation at 600 Torr while oxidation at 80 mTorr is self-limiting at 20 Å. The interfaces between the dielectric and the substrate have been characterized by scanning transmission electron microscopy. The ZrO2 films were found to be crystalline as grown. Electrical measurements on capacitor structures with 30-Å-thick ZrO2 films grown on native oxide on silicon show a capacitance–voltage hysteresis of 15 mV and a capacitance-based equivalent oxide thickness of 17 Å at 100 kHz.

The effect of specular electron scattering on the natural oxidation of a free layer in NiO spin valves has been investigated. The magnetoresistance ratio and the exchange biasing field (H ex ) of NiO(600 Å)/Ni 81 Fe 19 (50 Å)/Co(7 Å)/Cu(20 Å)/Ni 81 Fe 19 (70 Å) spin valves were increased from 4.9% to 7.3%, and 110 to 170 Oe after the natural oxidation in the atmosphere for 80 days, respectively. The sheet resistance decreased from 28 to 17 ⍀ m, but ⌬ did almost not change after the oxidation. The spin valves enhanced by the specular electron scattering in the naturally oxidized Co/NiFe/NiFeO x free layer were confirmed from the depth profiles using Auger electron spectroscopy.

A systematic structure characterization of nano-oxide layers ͑NOLs͒ and specular spin valves using x-ray diffraction and high-resolution transmission electron microscopy ͑HRTEM͒ has been studied. High-angle x-ray diffraction data show almost identical fcc textures for both natural and plasma NOL spin-valves. Low-angle x-ray reflectivity spectrum shows more deteriorated Kiessig fringes at high incident angles for natural oxide sample, indicating rougher interfaces in natural oxidation than in plasma oxidation. Oxygen exposure plays an important role in NOLs process. Fabricating NOLs without any crystal structure degradation is critical to obtain high MR ratio. HRTEM reveals that oxide clusters mixing with insufficiently oxidized CoFe layers prevailed in natural NOL, and the natural oxidation was inhomogeneous. In contrast, plasma NOL has a thinner, more homogeneously oxidized CoFe layers with sharp interfaces. In plasma NOLs, the structures still maintain CoFe crystal structure. The structures and magnetic correlation of the NOL specular spin valves are discussed.

The top-type tunneling magnetoresistance (TMR) multilayer films with a structure of Ta5/NiFe10/ Ta5/NiFe10/FeMn10/NiFe2/CoFe2/Al 2 O 3 1/CoFe3/NiFe20 (thickness in nm) with in-situ natural AlO x oxidation were deposited by a sputtering system with a base pressure of 10 --9 Torr. Junctions with sizes from 4 to 80 mm 2 were fabricated by using a conventional photolithography process. The as-deposited junction showed TMR of 16% at room temperature with resistance of 14-15 W, dependent on junction area. IntroductionThe tremendous increase of magnetic recording areal density was partly possible because of this new generation of reading head. For applying TMR read head, to overcome several demerits of high junction resistance such as noise, impedance matching problem, and delay time, it needs to have its resistance time junction area product (R Â A) lowered below a few hundred W mm 2 [1, 2]. From in-situ natural oxidation of Al 2 O 3 , SDT devices can solve the problems of pinholes, barrier doping effect, and overoxidized ferromagnet surface [3,4].In this paper, we present the fabrication of ion beam deposited (IBD) exchanged bias SDT devices using in-situ natural oxidation of Al. The IBD method can produce higher quality thin films (less defects), making IBD devices a good candidate for the deposition of thin Al films in the junctions. Results from micron-sized junctions based on top TMR structure of FeMn/NiFe/CoFe/Al 2 O 3 /CoFe/NiFe are presented. TMR is 8-17% at room temperature, dependent on 80-500 W mm 2 . Annealing of these junctions at 185 C slightly increases the TMR signal, with a slight decrease in junction resistance.