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Doped n- and p-type hydrogenated silicon (Si:H) thin films prepared by plasma enhanced chemical vapor deposition have been investigated for uncooled microbolometer applications. The material microstructure has been studied by in situ real time spectroscopic ellipsometry collected during thin film deposition or ex situ spectroscopic ellipsometry measurements on a static sample with a multiple sample analysis technique. The key electrical properties of interest, including film resistivity (ρ), temperature coefficient of resistance (TCR), and 1/f noise, have been measured as a function of deposition conditions for p-type amorphous hydrogenated silicon (a-Si:H) films and microcrystalline content for n-type amorphous (a), microcrystalline (µc), and mixed-phase amorphous + microcrystalline (a + µc) Si:H films. The TCR and 1/f noise values were compared for p- and n-type a-Si:H samples in the resistivity range of 100 < ρ < 3000 Ω cm and show that for a given resistivity, amorphous p-type films exhibit a lower 1/f noise, which might be expected due to a larger density of majority carriers. [ABSTRACT FROM AUTHOR]

Hydrothermal growth of ZnO on the annealed titanate nanotube films results in the oriented hexagonal-needlelike structures. The size, shape, density, and alignment of ZnO film are significantly affected by annealing temperature and orientation of the beneath titanate layer. It is believed that oxygen and hydrogen vacancies, generated due to dehydration of interlayered OH groups while annealing of the titanate, are responsible for the changes in the morphology of the ZnO. Microscopic observations clearly resolved nanoneedles with the base diameter of ∼150 nm and length of ∼5 μm with lattice spacing of 0.52 nm, indicating single crystalline ZnO and grown along the (0001) direction. A growth model is presented based on the layer-by-layer growth (three-step growth) as a function of growth time (2–6 h). Thicknesses of these three steps were found increasing with growth time. The second step (II) of growth exhibits the same feature as that of the first step (I), i.e., bounded with six crystallographic, lower surface energy facets of {0110} surfaces and capped with {0111} planes, but with higher step thickness and sharper tip. Finally, the obtained ZnO nanoneedles exhibit {0111} facets, the third step (III), with sharp tip in the [0001] direction. [ABSTRACT FROM AUTHOR]

When an organic layer on a conducting substrate is exposed to intense x rays, such as in scanning photoelectron microscopy (SPEM), the photoelectron spectrum for the exposed area shows a kinetic energy shift towards higher binding energy due to the accumulation of local charges. We present experimental evidence that in the thin organic layer of approximately 100 nm thickness in organic light-emitting devices, there exists an unshifted spectral component besides the local-charging-shifted spectral component. This finding enabled us to reliably investigate the chemical structures of organic layers using SPEM, which was shown to be advantageous in obtaining the space-resolved chemical structural information of a specimen. [ABSTRACT FROM AUTHOR]

A templated Cu/Co bilayer gate electrode was fabricated using the combined method of consecutive and selective chemical vapor deposition (CVD), and octadecyltrichlorosilane (OTS) microcontact printing techniques. Soft lithographically patterned self-assembled monolayers (SAMs) can direct the growth of Co occurring at the low temperatures 50–90 °C and serve as a template for the consecutive and selective growth of Cu, thereby forming stable and high quality Cu/Co bilayer gate electrodes on a glass substrate. This simple process provides fewer process steps and higher performance than other conventional processes, and can be applied to the fabrication of large area and high resolution thin film transistor liquid crystal displays. [ABSTRACT FROM AUTHOR]

The degradation process of a top-emission organic light-emitting device (TOLED) under high-bias voltage was investigated using a scanning photoelectron microscope (SPEM). The TOLED was in situ biased to reveal the degraded area inside the SPEM chamber. The SPEM data showed a volcano-type structure inside the degraded area. The overall results of the spectroscopic analysis suggest that strong degradation was accompanied by an eruption underneath the cathode layer. It is posited that the hot gases from the erupted area separated the cathode layer from the organic layer, forming a large bubble, and that, as the bubble exploded, the pressure of the gas blew away the cathode layer. [ABSTRACT FROM AUTHOR]

Plasma-nitrided SiO2 thin film has been analyzed by synchrotron-radiation-based x-ray absorption and photoelectron spectroscopies (XAS and XPS). High-resolution N 1s XAS and N 1s, O 1s, and Si 2p XPS spectral changes were obtained for different annealing temperatures. N 1s XPS and XAS spectra show that at room temperature, besides the main species of N[Si(O-)3-x]3, there exist free moleculelike N2 and HN[Si(O-)3]2, H2NSi(O-)3, and N–Si2O species with surface contaminants. The spectral intensities of the N2 and the HN[Si(O-)3]2, H2NSi(O-)3, and N–Si2O species decrease as the annealing temperature increases, and finally the nitrogen exists dominantly in the form of N[Si(O)3]3 species above 820 K, indicating out-diffusion of molecular N2 and structural reconstruction to form a stable structure upon annealing. The Si 2p and O 1s XPS spectra show that Si>4+ 2p peak and O 1s peak appear at 103.7 and 534.0 eV, respectively, which are higher binding energies than those of thermally grown oxynitride films with lower coverage on silicon. Upon annealing the sample, these peaks shift towards lower binding energy; ∼0.3 eV for Si>4+ and 0.4 eV for O 1s. The causes of the peaks appearance at relatively higher binding energy and the peak shift upon annealing are discussed. [ABSTRACT FROM AUTHOR]

Polycrystalline La0.7Ca0.3MnO3-δ (LCMO), prepared by a solid-state reaction, was annealed at different temperatures TA. The variation of TA was responsible for observed changes in the physical properties, including a shift in the metal-insulator transition temperature, which is explained by variation in the oxygen content. At low temperatures the magnetization of LCMO samples was also observed to be dependent on TA. A reduction of the grain boundaries leads to enhancement of both the magnetization and the sensitivity for low-field magnetoresistance. By using Mn L3-edge x-ray absorption, it was also found that the Mn3+/Mn4+ ratio increases with the grain size, and that the oxygen content in LCMO is governed by the grain boundaries. [ABSTRACT FROM AUTHOR]

The family of solid solutions of the type β-K2(Bi1-zSbz)8Se13 (0

The temporal changes of the kinetic energy spectra of photoelectrons emitted from micrometer-thick insulating layers, SiO[sub 2], and photoresist layers, were investigated with microfocused soft x rays in soft x-ray spectromicroscopy. The energy spectra of the insulators shifted up to several tens of electronvolts toward lower energies within seconds of the initial exposure. The amount of the energy shift depended on the thickness of the insulators. For the photoresist insulator, which was susceptible to radiation damage, the energy shift then decreased as the exposure time increased. The main cause of this decrease is attributed to the increase of conductivity by the x-ray-induced chemical state change of the insulator along the x-ray path. It was also demonstrated that by choosing appropriate time and energy in detecting photoelectrons the spectromicroscopy could be used as a depth probe of the conducting microstructures covered by insulating layers. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Raman spectroscopy has been used to assess the concentration dependence of optical phonons in In[sub 1-x]Ga[sub x]As epilayers grown by chemical beam epitaxy on InP(100). The alloy composition was varied from x=0.325 to x=0.55 to cover the technologically important and physically interesting range where the strain changes sign at x=0.468 from negative to positive. The Raman spectra were curve resolved to reveal the GaAs-like longitudinal optic (LO), disorder induced, InAs-like LO, and InAs-like transverse optic phonons. An examination of the concentration dependence of the phonon frequencies showed that the GaAs-like LO mode varied as ω(cm[sup -1])=252.77+58.643x-50.108x[sup 2] for 0.325≤x≤0.55. A comparison of these results with previous infrared and Raman work on In[sub 1-x]Ga[sub x]As has revealed that the concentration dependence of the optical phonon frequencies in the unstrained system is still not accurately known. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Examines the substrate temperature effects on the preparation of yttrium-barium-copper oxide superconducting films on strontium-titanium oxide. Use of laser ablation in depositing superconducting thin films in a substrate; Experimental details; Result of the study.

The electronic structures of SrMn1-xFexO3 (0≤x≤1) have been investigated by using photoemission spectroscopy (PES) and soft x-ray absorption spectroscopy (XAS). Mn ions in SrMnO3 are found to be in the nearly tetravalent (Mn4+) states, but with a small mixture of the Mn2+ configuration. With increasing x in SrMn1-xFexO3, Mn ions remain in the 4+ states. Fe ions in SrMn1-xFexO3 are also in the nearly tetravalent (Fe4+) states for the whole range of x. Valence-band PES reveals that the occupied Mn t2g3 states are located about 2.5 eV below EF, while the occupied Fe t2g3eg1 states are broader than the Mn 3d occupied states, and are located between 3 and 6 eV below EF. The large overlap between Fe 3d and the O 2p states is found in SrFeO3, reflecting the strong hybridization between the Fe 3d states and the O 2p states, in agreement with the metallic nature of SrFeO3. [ABSTRACT FROM AUTHOR]

The spatial chemical distributions of doped T ions and their local electronic structures in Zn1-xTxO (T=Mn, Fe, Co; x<=0.1) have been investigated simultaneously by using scanning photoelectron microscopy (SPEM), photoemission spectroscopy (PES), and soft-x-ray absorption spectroscopy (XAS). The measured SPEM images for Zn1-xTxO single crystals reveal the uniform chemical distributions of T ions, indicating the homogeneous substitution of T ions for Zn sites. The T 2p XAS spectra of Zn1-xTxO show that Mn and Co ions are in the divalent states, while Fe ions are in the Fe2+–Fe3+ mixed-valent states. The valence-band PES study of Zn1-xTxO (T=Mn, Fe, Co) shows that T 3d states lie near the top of the O 2p valence bands. Only ferromagnetic Zn1-xTxO shows a significantly large Fe 3d photoemission intensity near EF, in contrast to the negligible Mn and Co 3d photoemission intensities near EF in nonferromagnetic Zn1-xTxO (T=Mn, Co), suggesting that the high carrier density is important in determining the ferromagnetic behavior of Zn1-xTxO. [ABSTRACT FROM AUTHOR]

The electronic structures of BxA2-xFeMoO6 (A=Ba,Sr;B=La,K) double perovskites have been investigated by using photoemission spectroscopy and soft-x-ray absorption spectroscopy (XAS) near the Fe 2p and O 1s absorption edges. The Fe 2p XAS spectra of undoped A2FeMoO6 (A=Ba,Sr) provide evidence for the mixed-valent Fe2+–Fe3+ states. The substitution of La3+ and K+ ions for A2+ ions causes the increasing Fe3+ component and increasing Fe2+ component, respectively. The states close to the Fermi level have mainly the Mo–Fe t2g(↓) character, consistent with the Fe2+–Fe3+ mixed-valent states. As the amount of the K+ substitution increases in KxSr2-xFeMoO6, the photoemission intensity near the Fermi level decreases, reflecting the decreasing carriers and the decreasing bandwidth of the itinerant t2g(↓) states. [ABSTRACT FROM AUTHOR]

Electronic structures of delafossite AgTO2 (T=Fe,Co,Ni) have been investigated by using photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS). The T 2p XAS spectra of AgTO2 show that Fe and Co ions are in the trivalent states but that Ni ions are mainly in the divalent states, suggesting that the metallic nature of AgNiO2 arises from hole carriers due to divalent Ni ions. The valence-band PES study of AgTO2 (T=Co,Ni) reveals that T 3d states are located close to EF and that the Ni 3d band is more metalliclike than the Co 3d band. [ABSTRACT FROM AUTHOR]

The chemical distributions and electronic structures of Ge1-xTx (T=Cr, Fe) diluted ferromagnetic semiconductors have been investigated by employing scanning photoelectron microscopy (SPEM), x-ray absorption spectroscopy (XAS), and photoemission spectroscopy (PES). The SPEM images and PES spectra of Ge1-xTx show the stripe-shaped regions due to the inhomogeneous concentration distributions of T ions. T 2p XAS spectra indicate that T ions are mainly in the divalent states, and that they do not form pure metal clusters. This study reveals that Ge1-xTx crystals are chemically phase-separated, suggesting that the observed ferromagnetic ordering in Ge1-xTx arises from the magnetic properties of the T-rich Ge1-xTx phases. [ABSTRACT FROM AUTHOR]

The concentration dependence of the zone-center optical phonons in strained In[sub 1-χ]Ga[sub χ]As epilayers grown by chemical beam epitaxy on InP(100) has been measured with oblique angle, polarized far infrared reflectivity measurements. The spectra, containing distinct peaks at the phonon frequencies, were curved resolved for the individual phonon modes which included GaAs-like longitudinal optic (LO) and transverse optic (TO), disorder induced, and InAs-like LO and TO phonons. The concentration dependence of the phonon frequencies, examined for 0.31 < χ < 0.56, showed a nearly linear dependence on gallium fraction. [ABSTRACT FROM AUTHOR]

Focuses on a study which examined ferroelectric barium titanate thin films grown on silicon substrates by in situ metalorganic chemical vapor deposition. Description of barium titanate; Composition of the carrier gas; Details on the results.

Presents information on a study which examined the dependence of cobalt/palladium multilayered films' magnetic properties on the structural parameters estimated by x-ray diffraction. Factors attributed to the research on transition-metal/noble metal multilayered thin films with the development of shorter wavelength lasers; Methodology of the study; Results and discussion.

Examines the effects of composition and additives on the microstructures and magnetic properties of neodymium-iron-boron melt-spun ribbons. Use of x-ray diffractometry and scanning electron microscopy; Composition effect on the microstructures; Increase in coercivity and remanence by addition of elements.

A Mn[sup 2+] ion-doped β-Ga[sub 2]O[sub 3] single crystal was grown by using a floating zone method. By employing an X-band electron paramagnetic resonance (EPR) spectrometer, Mn[sup 2+] EPR spectra were recorded at room temperature. The rotation patterns in the crystallographic planes together with spin-Hamiltonian parameters of Mn[sup 2+] show unequivocally that the actual local site symmetry of the Mn[sup 2+] ion is monoclinic. A Mn[sup 2+] ion lies on a site with a two-fold rotation symmetry, parallel to the monoclinic axis of the crystal. The spectroscopic splitting tensor g, zero-field splitting parameters B[sub k][sup q]s, and the hyperfine tensor A are determined with the effective spin Hamiltonian. It turns out that the Mn[sup 2+] ion lies at only one site, the substitutional site for the Ga[sup 3+] ion in the oxygen octahedron rather than in tetrahedron. Energy levels of the ground state for a Mn[sup 2+] ion embedded in the β-Ga[sub 2]O[sub 3] crystal are calculated. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Polycrystalline La0.7Ca0.3MnO3-δ (LCMO), prepared by a solid-state reaction, was annealed at different temperatures TA. The variation of TA was responsible for observed changes in the physical properties, including a shift in the metal-insulator transition temperature, which is explained by variation in the oxygen content. At low temperatures the magnetization of LCMO samples was also observed to be dependent on TA. A reduction of the grain boundaries leads to enhancement of both the magnetization and the sensitivity for low-field magnetoresistance. By using Mn L3-edge x-ray absorption, it was also found that the Mn3+/Mn4+ ratio increases with the grain size, and that the oxygen content in LCMO is governed by the grain boundaries. [ABSTRACT FROM AUTHOR]

The electronic structures of SrMn1-xFexO3 (0≤x≤1) have been investigated by using photoemission spectroscopy (PES) and soft x-ray absorption spectroscopy (XAS). Mn ions in SrMnO3 are found to be in the nearly tetravalent (Mn4+) states, but with a small mixture of the Mn2+ configuration. With increasing x in SrMn1-xFexO3, Mn ions remain in the 4+ states. Fe ions in SrMn1-xFexO3 are also in the nearly tetravalent (Fe4+) states for the whole range of x. Valence-band PES reveals that the occupied Mn t2g3 states are located about 2.5 eV below EF, while the occupied Fe t2g3eg1 states are broader than the Mn 3d occupied states, and are located between 3 and 6 eV below EF. The large overlap between Fe 3d and the O 2p states is found in SrFeO3, reflecting the strong hybridization between the Fe 3d states and the O 2p states, in agreement with the metallic nature of SrFeO3. [ABSTRACT FROM AUTHOR]