Atomic layer deposition (ALD) of Sb2 Te3 /GeTe superlattice (SL) film on planar and vertical sidewall areas containing TiN metal and SiO2 insulator is demonstrated. The peculiar chemical affinity of the ALD precursor to the substrate surface and the 2D nature of the Sb2 Te3 enable the growth of an in situ crystallized SL film with a preferred orientation. The SL film shows a reduced reset current of ≈1/7 of the randomly oriented Ge2 Sb2 Te5 alloy. The reset switching is induced by the transition from the SL to the (111)-oriented face-centered-cubic (FCC) Ge2 Sb2 Te5 alloy and subsequent melt-quenching-free amorphization. The in-plane compressive stress, induced by the SL-to-FCC structural transition, enhances the electromigration of Ge along the [111] direction of FCC structure, which enables such a significant improvement. Set operation switches the amorphous to the (111)-oriented FCC structure.

The feasibility of new InSbTe (IST) chalcogenide materials at the deposition temperatures of 225 and 250 degrees C using metalorganic chemical vapor deposition (MOCVD) for phase-change random access memory (PRAM) applications was investigated. Samples grown at 225 degrees C consisted of the main InTe phase, including a small amount of Sb. On the other hand, samples grown at 250 degrees C included the crystalline phases of InSb and InSbTe. MOCVD-IST materials are powerful candidates for highly-integrated PRAM applications.

Flower-shaped indium oxide nanostructures were grown at a low temperature (250 °C) on Si (100) substrates by NCD technique without using metal catalyst. Bud shaped leaf like structures are obtained with lengths and diameters in the range of 150–250 nm and 75–125 nm, respectively, which are compacted into a flower-shaped structure. Transmission electron microscopy and selected area electron diffraction patterns taken on the leaf-like structure show crystalline cubic phase, with preferential orientation along (222) and (400) directions. The composition of indium and oxygen was confirmed from XPS analysis. The room temperature photoluminescence (PL) spectrum of flower-like In2O3 nanostructure shows a blue emission centered around 428 nm under the 383 nm UV excitation, which is mainly attributed to the oxygen vacancy in the In2O3 nano/microstructures. A growth model for the formation mechanism of the self-catalytic growth of flower shaped structure is proposed.

Thin-film resistors for the high resistivity and the low temperature coefficient of resistance (TCR) applications were prepared using the CrB2-Si-SiC (it was abbreviated as CrSS) target in an argon and oxygen mixture ambient on the SiO2/Si substrates by radio-frequency magnetron sputtering. The microstructural and electrical properties of the films were investigated for various deposition temperat...

Thin-film resistors for the high resistivity and the low temperature coefficient of resistance (TCR) applications were prepared using the CrB2-Si-SiC (it was abbreviated as CrSS) target in an argon and oxygen mixture ambient on the SiO2/Si substrates by radio-frequency magnetron sputtering. The microstructural and electrical properties of the films were investigated for various deposition temperatures. The resistivity and the TCR values of the films were remarkably varied with increasing deposition temperature. Abrupt variations in the resistivity and the TCR values in the films grown above 550°C were attributed to the nanocrystalline Cr2SiO4 phases embedded in the amorphous phases. The 91-nm-thick samples grown at 565°C in an argon and oxygen mixture ambient exhibited a resistivity as high as 1.0 kΩ/sq and a TCR value as low as -6 ppm/°C. The resistivity and the near-zero TCR values of the thin films grown at various temperatures are a strong candidate for high-resistivity thin-film resistor applications.

High quality indium tin oxide (ITO) thin films were grown by the nanocluster deposition (NCD) technique at a low temperature. The ITO films were examined using a four-point probe and Hall probe measurements, scanning electron microscopy, atomic force microscopy, X-ray fluorescence, X-ray diffraction, and X-ray photoelectron spectroscopy. The lowest resistivity (1.8 X 10(-4) Omega cm) and highest optical transparency (92%) were obtained for films containing a tin concentration of 7 wt %. The absence of hydroxyl groups, organic contamination, and carbon content in the films grown at a low temperature of 250 degrees C by NCD indicates the complete decomposition of metallorganic precursors. Excellent optoelectronic and surface chemical properties can be favorable for a transparent electrode in many display technologies. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3467802] All rights reserved.

The feasibility of InSbTe chalcogenide materials prepared by metallorganic chemical vapor deposition (MOCVD) for phase-change memory (PRAM) applications was demonstrated. Films grown below 225 degrees C exhibited an amorphous structure, and the films grown at 300 degrees C included various crystalline phases such as In-Sb-Te, In-Sb, In-Te, and Sb-Te. The composition of the amorphous films grown at 225 degrees C was dependent on the working pressure. Films grown at 225 degrees C exhibited a smooth morphology with a root-mean-square roughness of less than 1 nm, and the step coverage of the films grown on a trench structure with an aspect ratio of 5:1 was greater than 90%. An increase in deposition time increased the filling rate while retaining the conformal step coverage. Films grown at 225 degrees C for 3 h in a working pressure of 13 x 10(2) Pa exhibited a reproducible and complete filling in a trench structure. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3363618] All rights reserved.

The feasibility of InSbTe (IST) chalcogenide new materials by metalorganic chemical vapor deposition (MOCVD) was demonstrated for PRAM applications. IST-MOCVD at a low temperature of 250 degrees C resulted in a favorable conformal deposition in the trench structure with a high aspect ratio. The IST films grown at 250 degrees C showed the highest resistance of approximately 10(8) Omega/sq, suggesting the amorphous phase of IST and the films grown at 300 degrees C include various crystalline phases of IST, In-Sb, and In-Te. MOCVD-IST films exhibited a step-coverage of about 95% in the trench structure with a 5 : 1 aspect ratio (a height of 500 nm and a diameter of 100 nm) and also showed reliable filling of the trench under appropriate deposition conditions. Phase switching between amorphous and crystalline states in the IST films grown on a trench structure at a high-aspect ratio (3.5 : 1) was demonstrated showing functional characteristics for applications in memory devices. The IST-based chalcogenide films used included various crystallized phases of In-Sb-Te, In-Sb and In-Te, which proved to be favorable for multilevel data storage.

Phase-change InSbTe (IST) single crystalline nanowires were successfully synthesized at a low temperature of 250 degrees C by metalorganic chemical vapor deposition (MOCVD). The growth of IST nanowires by MOCVD, at very high working pressure, was governed by supersaturation. The growth mechanism of the IST nanowires by MOCVD is addressed in this paper. Under high working pressure, the InTe phase was preferentially formed on the TiAlN electrode, and the InTe protrusions were nucleated on the InTe films under high supersaturation. The Sb was continuously incorporated into the InTe protrusions, which was grown as an IST nanowire. Phase-change-induced memory switching was realized in IST nanowires with a threshold voltage of about 1.6 V. The ability to grow IST nanowires at low temperature by MOCVD should open opportunities for investigation of the nanoscale phase-transition phenomena.

The thermal stability of the GeSbTe (GST) films deposited by layer-by-layer metalorganic chemical vapor deposition on the planar TiAlN∕Si and on trenches 120nm in diameter and 500nm deep (with aspect ratio of 4:1) was investigated under various annealing temperatures and durations in a nitrogen ambient atmosphere. The inhomogeneous distribution of the Ge and Sb elements in the as-grown GST layer was improved by a thermal treatment at 500°C for 60min in nitrogen ambient. The GST films annealed above 500°C for 30 and 60min were delaminated from the TiAlN electrode. Samples annealed at 700°C for 1min, above the melting temperature of the GST, show a decreased thickness, indicating that the GST films were thermally unstable. The as-grown films on trenches did not show a complete fill of the structure, whereas the trenches were more fully filled after a thermal treatment at 500°C for 60min.

Relationship between the dark- (without a light) and photo- (with a light) resistance values by a visible light is addressed using non-stoichiometric CdS:H films grown on polyethersulfon (PES) flexible polymer substrates at room temperature by radio frequency magnetron sputtering technique. The CdS:H films deposited at a hydrogen flow ratio of 25% exhibited a dark- and photo-sheet resistance of 2.7 × 105 and ∼50 Ω/square, respectively. These values were realized by an optimum control of both hydrogen doping-levels and the surface morphologies of the films. The comparison between the real and the simulated results for the shielding and the transmission by the free space measurement system in the X-band frequency range (8.2–12.4 GHz) was also addressed in this study. Samples overlapped with 13 layers of CdS:H films were consistent with the transmission results of pure aluminum metal films (0.1 Ω/square) deposited on PES substrates. By the simple stacking of the CdS:H layers, the perfect control of the shielding and the transmission of the EM wave in the range of X-band frequency is possible by a visible light alone.

Ge, GeTe, and GeSbTe (GST) films are grown on both planar TiAlN/Si substrates and a trench structure (diameter 120 mu; depth 200 nm) using layer-by-layer, metal-organic (MO) CVD. The GeTe and GeSbTe films completely fill the trench structure, and show well-crystallized phases with a rhombohedral and hexagonal structure, respectively. The GeTe films grown on the trench structure exhibit stoichiometric variations along the depth of the trench. Stoichiometric Ge2Sb2Te5 Compositions are observed only at the center of the trench structure. The concept of layer-by-layer MOCVD could be applied for depositing GST and GeTe films from constituent precursors with large differences in decomposition temperatures, provided the composition variation can be overcome.

TiNxOy/TiNx multi-layer thin films with a high resistance(similar to k Omega) were deposited on SiO2/Si substrates at room temperature by sputtering. The TiNx thin films show island and smooth surface morphology in samples prepared by a and RF magnetron sputtering, respectively. TiNxOy/TiNx multi-layer in has been developed to control temperature coefficient of resistance(TCR) by the incorporation of TiNx layer(positive TCR) inserted into TiNxOy layers(negative TCR). Electrical and structural properties of sputtered TiNxOy/TiNx multi-layer films were investigated as a function of annealing temperature. In order to achieve a stable high resistivity, multi-layer films were annealed at various temperatures in oxygen ambient. Samples annealed at 700 degrees C for 1 min exhibited good TCR value of approximately -54 ppm/degrees C and a stable high resistivity around 20 k Omega/sq. with good reversibility.

The 30 nm thick Bi2Mg2/3Nb4/3O7 (BMN)(O)/200 nm thick BMN(Ar)/30 nm thick BMN(O) multilayer capacitors were prepared on Pt/TiO2/SiO2/Si substrates at room temperature by radio-frequency magnetron sputtering to improve both the dielectric constant and leakage current characteristics. The BMN(Ar) percolative capacitors and BMN multilayer capacitors show a dielectric constant of approximately 150 and 63 and dissipation factors of 0.08 and 0.02, respectively, at 100 kHz. The percolative capacitors show a large dispersion of the dielectric properties, while multilayer capacitors show a stable dielectric property as a function of frequency. The leakage current density of the multilayer capacitors shows 1 order of magnitude lower than that of the percolative capacitors. The conduction mechanism of the BMN multilayer films was mainly controlled by a Schottky emission having Schottky barrier heights of about 0.08-0.14 eV. The leakage current characteristics of the BMN percolative films were improved by an appropriate insertion of the BMN(O) interfacial layer at both sides of the BMN percolative films.