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Photo-induced carrier processes at the heteromolecular interface of N,N'-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C(8)) and quaterrylene (QT) on a molecular scale were examined by optical and photoelectron spectroscopy. The energy level alignments of the molecules were determined by X-ray photoelectron spectroscopy and the optical absorption spectra for detailed investigation of the photo-induced carrier process were analysed. A reduction in photoluminescence from PTCDI-C(8) on QT was observed, clearly demonstrating that the excitons generated in the PTCDI-C(8) layer are effectively dissociated at the heteromolecular interface. One important factor inducing this effective charge dissociation is the highly ordered molecular packing, which acts to increase the exciton diffusion length. Moreover, a specific increase in the photoluminescence excitation spectrum was observed around 3 eV, indicating that simultaneous exciton generation in both the QT and PTCDI-C(8) layers effectively suppresses such charge dissociation of the excitons. In other words, the existence of excitons in each molecule at the heteromolecular interface and HOMO-LUMO level alignment at the interface play an essential role in charge dissociation. Our results provide a striking insight into intermolecular interactions in the carrier process at the heteromolecular interface such as exciton generation, the recombination and dissociation processes, and the photovoltaic effect in organic semiconductors.

We have fabricated Si/β-FeSi2 particles/Si structures by reactive deposition epitaxy for β-FeSi2 and molecular-beam epitaxy (MBE) for Si. It was found that the photoluminescence (PL) intensity of β-FeSi2 strongly depended on MBE-Si growth temperature for embedding β-FeSi2 in Si. Room temperature 1.6 μm electroluminescence was realized from a Si-based light-emitting diode by embedding the β-FeSi2 active region with Si grown at 500 °C. Observation with transmission electron microscopy revealed that the a axis of β-FeSi2 from which PL was observed was about 9% longer than that of β-FeSi2 without PL or of bulk β-FeSi2.

Epitaxial anatase thin films were fabricated on lattice-matched (−0.2%) LaAlO3 (001) substrates in the layer-by-layer fashion by laser molecular-beam epitaxy. X-ray diffraction and transmission electron microscope show the films to exhibit high crystallinity and atomically defined interfaces. By virtue of the adoption of LaAlO3 substrate, which is transparent to photoexcitation of TiO2, optical band gaps could be determined to be 3.3 eV at room temperature. A photoluminescence band due to recombination of self-trapped excitons was observed at 5 K to give the peak maximum at 2.2 eV. As a result of the high degree of orientation of the epitaxial films, anisotropic optical absorption was clearly observed.

The room-temperature epitaxial growth of CeO2 films on Si(111) substrates was examined in situ by combined use of a coaxial impact-collision ion scattering spectroscopy (CAICISS) and the laser molecular beam epitaxy (laser MBE). It was found that the crystal quality of CeO2 ultrathin films (∼3 nm thick) as-grown in UHV (∼10−9 Torr) could be improved remarkably by a few minutes of O2 gas exposure (∼10−5 Torr) at room temperature. A three-fold symmetry in the Ce signal intensity of azimuth rotational CAICISS spectra, which exhibited the type-B epitaxial growth ([110]CeO2‖[110]Si), was observed for the films thicker than about 1 nm.

We have examined the impact of a simple, wet chemical postgrowth treatment of “immersing in KCN solution” on the performance of inverted staggered amorphous silicon n-channel thin film transistors. Results show that the cyanide treatment significantly improves the overall transistor performance by the elimination of defect states.

Dilute magnetic semiconductors and wide gap oxide semiconductors are appealing materials for magnetooptical devices. From a combinatorial screening approach looking at the solid solubility of transition metals in titanium dioxides and of their magnetic properties, we report on the observation of transparent ferromagnetism in cobalt-doped anatase thin films with the concentration of cobalt between 0 and 8%. Magnetic microscopy images reveal a magnetic domain structure in the films, indicating the existence of ferromagnetic long-range ordering. The materials remain ferromagnetic above room temperature with a magnetic moment of 0.32 Bohr magnetons per cobalt atom. The film is conductive and exhibits a positive magnetoresistance of 60% at 2 kelvin.

ZnS films were grown on Si (100) at high temperatures by pulsed laser deposition using a KrF excimer laser. The growth temperature was varied from 200 to 700 °C and all films were found to have a specific preferential orientation. With increasing Ts, growth rate decreased but the quality of the film improved. The highest quality ZnS film was obtained at 700 °C. The presence of ZnS+ ions among the ablation products of a ZnS target was verified by laser desorption time of flight mass spectroscopy measurements. ZnO was formed by thermal oxidation of ZnS and the films showed strong near band-edge emission at 3.26 eV.

We have revealed by the first-principles calculations that the workfunction of silicide is controlled by the high-density dopant existing in the silicide itself, and the selective doping into Si or Ni site is essential to realize such control. In addition, we showed that these doping properties are closely related to fundamental physics of silicides; why Ni x Si y exists and why Au x Si y not exists in nature. These findings might give a new guideline to design silicide-electrode contacts for future 10nm nano-devices.

We have investigated the role of oxygen in Hf-based high-k gate stacks on Vfb shift. It is clearly shown that the Vfb of the HfSiO x -based high-k materials of the weak ionic oxide was almost constant irrespective of the oxidation annealing temperature. On the other hand, the HfO 2 -based high-k materials of the strong ionic oxide caused the positive Vfb shifts by introducing additional oxygen into high-k films. These suggest that the control of strength of ionic bond and oxygen content due to the oxygen transfer at hetero interface of ionic high-k/covalent SiO 2 is a key if it assumes that the Vfb shift occurs dominantly at high-k/SiO 2 interface.

We evaluated the three types of composition spread passivation layer, i.e., Al2O3–HfO2, HfO2–Y2O3, and Al2O3–Y2O3 systems, by combinatorial pulsed laser deposition to evaluate and control the fixed charge, while interface states were kept constant with a SiO2 interlayer. The flat-band voltage of the capacitance–voltage (C–V) curves was shifted widely from positive to negative by changing the composition. The calculated fixed charge in the Y2O3 was positive while those in the HfO2 and Al2O3 were negative. In the Al2O3–Y2O3 system, the fixed charge was significantly varied between -2.7 and 1.3×1012 cm-2 with composition spread. The maximum negative charge was found in the Al2O3 layer with a slight amount of Y2O3, while the maximum positive charge was realized with almost pure Y2O3. The fixed charge modifications were also found in the Al2O3–HfO2 and HfO2–Y2O3 systems. Additional oxidation after layer deposition also modified the fixed charge properties. The largest negative fixed charge of -3.1×1012 cm-2 was found in approximately HfO2:Y2O3=1:1 after the annealing process, while the largest positive charge of 1.3×1012 cm-2 was found for Y2O3 with Al2O3 incorporation. The passivation layers with controlled fixed charge can be promising materials for the high-quality passivation layer in crystalline silicon solar cells.

We investigated the evolution of quaterrylene thin films on SiO(2) and on an octadecyltrichlorosilane self-assembled monolayer (OTS-SAM) to examine the impact of film strains on the growth processes and evolving structure. Surface modification by SAMs allowed tailoring of the growth process from a Stranski-Krastanov (SK) mode (layer-plus-island) on the SiO(2) surface to a Frank-van der Merwe mode (layer-by-layer) on the OTS surface. Detailed structural analysis by x-ray diffraction techniques confirmed that the SK mode was driven by lattice strain in the initial wetting layers on the SiO(2) surface. On the other hand, strain-free wetting layers were already formed at the beginning of growth on the OTS surface, thereby suppressing three-dimensional island formation. Moreover, the films on the SiO(2) surface were found to incorporate high microstrain induced by crystal defects such as dislocations and a mosaic structure. In contrast, few crystal defects were present in the films on OTS surface, demonstrating that OTS treatment enables marked improvement of the molecular alignment. These results clearly indicate that the lattice strain induced by the molecular-substrate interaction is essential for controlling the overall growth process.

Anomalous threshold voltage increase with area scaling of Mg- or La-incorporated high-k gate dielectrics has great impact on scaled devices. This paper reveals that much amount of Mg or La capping effects for V t reduction was disappeared with the increase of electron mobility in narrow channel nMISFETs. This phenomenon is explained with absorption of Mg and La into STI from bulk high-k layer. The key to suppress the area scaling dependence is pilling Mg or La atoms up near high-k/IFL interface which enable us increase of stable capping effect. Combination of processing for high-k gate dielectrics and device structure with the high-k dielectrics under offset spacers was found to effectively suppress the V t increase at the 100 nm channel width. As a conclusion, the large capping effect for V t reduction over 400 mV is achieved in scaled devices using this technique.

Microscopical investigation of leakage behaviors of Hf-based high-k gate stacks was achieved by means of electron-beam-induced current (EBIC) method. With this method, we could observe the pre-existing and stress induced defect in high-k. This pre-existing defect affect on MOSFET characteristics. We investigated in detail the relationship between the defect (in bulk high-k and interface) and 1/f noise on (110) and (100) substrates. The 1/f noise is strongly related to the degradation in the hole mobility due to the pre-existing defect or process integration damage. On the other hand, the 1/f noise of nMOSFETs is rerated to interface defects rather than electron mobility degradation.

Microcrystals of GaAs were grown on a Se-stabilized ZnSe and on a Zn-stabilized ZnSe surface by As incorporation into Ga droplets. The size of the GaAs microcrystals on the Zn-stabilized surface was smaller than that of those on the Se-stabilized surface. The size difference is explained by the reduced diffusivity of Ga atoms on the Zn-stabilized ZnSe surface, where active (111) dangling bonds of Se atoms are exposed neighbored by top Zn atoms.

The dielectric degradation under electrical stress application was attributed to generation of oxygen vacancy, and structural transformation in HfSiON films, in addition to widely known charge trapping. The former two result from ion drift under electrical field due to its ionic character of Hf-based dielectrics. While V o generation and charge trapping are atomic-range phenomena, it is surprising that long-range structural transformation can also occur under electrical filed before dielectric breakdown even at room temperature.

We examined the film morphologies and transistor properties of hetero-molecular bilayer consisting of N, N’-dioctyl-3, 4, 9, 10-perylenedicarboximide (PTCDI-C8) and quaterrylene. First, the structure and carrier conduction of PTCDI-C8 films were studied, followed by an analysis of the carrier accumulation process in a PTCDI-C8/quaterrylene hetero-bilayer transistor. Based on the displacement current measurement (DCM), we stress the potential of the hetero-bilayer for tuning carrier accumulation like carrier doping techniques in field-effect transistors.

application/pdf, A molecular superlattice consisting of alternate layers of N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) and quaterrylene was prepared by using an ultra-slow deposition technique. Film growth under equilibrium conditions with precise optimization of the substrate temperature enabled the layer-by-layer stacking of hetero-molecules at a single-layer level. The morphology of the films and the orientation of the molecules in each layer were analyzed by atomic force microscopy (AFM) and an X-ray reflection (XRR) technique.

We propose a new MBE growth method for InSb microcrystals on CdTe which has a nearly equal lattice constant to InSb. The average size of the InSb microcrystals was about 150 nm × 200 nm × 70 nm. This method is based on the Sb incorporation into In droplets and thought to be useful for fabricating quantum well boxes.

We synthesized cubic nanoassemblies of octahedral CeO(2) nanocrystals by simply heating an aqueous solution of cerium nitrate (Ce(NO(3))(3)) in the presence of hexanedioic acid (HOOC(CH(2))(4)COOH) in a lab-scale plug-flow reactor. It was concluded that the octahedral shape of the primary CeO(2) nanocrystals plausibly leads to octa-coordination of the primary nanocrystals, thus enabling controlled assembly to form a cubic structure.

We have clarified that, in a metal/high-k gate stack, as well as the variability introduced by random dopant fluctuations (RDF), the threshold voltage variability (TVV) is attributable to the crystal structure and grain size in the metal gate. We have successfully eliminated this additional factor by reducing the grain size in the metal gate. We demonstrated that the incorporation of C into TiN metal gates transforms the crystalline film into an amorphous one, effecting a reduction in the TVV in HfSiON pFET devices. We observed that the TVV of C-incorporated TiN devices was dominated by RDF, indicating that the additional factor due to the metal gate had been diminished.

Ni silicide films were formed on both heavily doped n+ and p+ Si substrates at various temperatures ranged from 200°C to 950°C and its electrical and structural properties were studied. It was found that the phase transition temperature from NiSi phase to NiSi2 phase depend on substrate types; 900°C for NiSi film on n+ Si substrate and 750°C for NiSi film on p+ Si substrate, respectively. It was also found that agglomerations of Ni silicide films on n+ Si substrates begin to occur at the annealing temperatures around 600°C while there is no agglomeration observed in Ni silicide films on p+ Si substrates up to 700°C. Obtained results show that the agglomeration is especially important factor in the process temperature dependency of the sheet resistance of Ni silicides formed on n+ Si substrates. It was also demonstrated that the agglomeration can be suppressed by an inserted thin Boron layer at the interface of Ni/Si.

We demonstrate a comprehensive study of self-assembled molecular nanowire, including molecular design, one-dimensional crystal growth, resistivity measurement of individual wire, and application to a field-effect transistor. Appropriate molecular design and control of interfacial interactions lead to single crystalline wire growth with an extensive pi-stacking motif. Resistivity measurements of an individual molecular wire indicate that these structural features are advantageous for electrical transport. Finally, field-effect transistors with single- and double-wire channels were fabricated to give some indication of the potential application of the molecular wires.

We report the formation of standing mesochannels simply by spin-coating a precursor solution onto a PAA (porous anodic alumina) substrate with designed conical holes, utilizing exactly the same precursors and reaction conditions that form two-dimensional (2D) hexagonal mesoporous SBA-15-type films. When the aspect ratios of the conical holes are lower, the sponge-like mesopores are generated within the conical holes. Such a formation of sponge-like mesostructures truly acts as a trigger for the evolution of perpendicularly oriented and tilted mesochannels. On the other hand, when the PAA substrates with high-aspect cones are used, the mesochannels are stacked like a doughnut within the conical holes, which leads to parallel orientations of the mesochannels in the continuous film region.

Microscopical investigation of leakage behaviors of Hf-based high-k gate stacks was achieved by means of electron-beam-induced current (EBIC) method. Carrier separated EBIC measurement has found that in non-stressed samples, hole conduction in pMOS is significantly enhanced by trap-assisted tunneling, while electron conduction in nMOS is independent of traps. The transport mechanisms of electron and holes in non-stressed high-k MOS capacitors were clarified. After stressing, positive charged traps are induced in nMOS and enhance electron conduction.

Quaterrylene field-effect transistors (FETs) with top-contact Au electrodes were formed on a SiO2 (200nm)∕p-Si (001) substrate by an ultraslow vacuum deposition technique, and their carrier transport was investigated. The quaterrylene FETs showed typical p-channel transistor behavior. The dependence of carrier mobility on grain size, film thickness, and temperature was examined to gain insight into the transport mechanism. Carrier mobility increased with grain size, showing that carrier transport was limited by grain boundaries. Temperature dependence in the range from 300to60K was divided into two distinct behaviors. Above 210K, carrier mobility showed thermally activated behavior, with energies of 100–150meV required to overcome the potential barriers at grain boundaries. In contrast, the conduction mechanism became tunnel-transfer-like below 210K. In the low temperature range, tunnel transfer through potential barriers at grain boundaries predominated over the thermally activated type. The change in carrier mobility was correlated with film thickness. Carrier mobility rose sharply with increasing thickness in the two-dimensional (2D) growth region, followed by saturation at 3 or 4 ML, where the growth process changed from 2D to three-dimensional mode. This result reveals that the first few layers of 2D growth work as an effective transistor channel. Enhancement in 2D growth in the vertical direction is crucial to improving carrier transport.

We investigated the impact of interface modification by an octadecyltrichlorosilane self-assembled monolayer (OTS-SAM) on growth mode and transistor performance of quaterrylene thin films. Interface modification by OTS-SAM contributed effectively to stress-free film growth and highly molecular ordering, particularly in the initial layers, dramatically improving transistor performance. We found that the structural features in a few layers were key factors for determining the overall thin film growth mode and ameliorating carrier transport in organic field-effect transistors (OFETs). These results clearly demonstrated the effectiveness of interface engineering in the OFETs.

We propose here cost-effective gate-first dual-metal/dual-high-k CMOS technology in which Fermi-level pinning is "positively" utilized to reduce threshold voltages for the first time. After systematic investigation on the relation between oxygen vacancies in Hf-based high-k film and electrical characteristics, we concluded that the Fermi-level pinning is unavoidable in principle with a thin EOT, but is a stable phenomenon that should be intentionally utilized. In our proposed method, source of oxygen interstitials (Al) is contained in metal gate material for p-FET, and consequently the flatband voltage is properly modulated by "opposite" Fermi-level pinning due to the oxygen interstitials incorporated into the underlying high-k film after high temperature annealing. It is also noteworthy that this method is simple and cost-effective because the initial high-k films are identical for n-and p-FET but they are automatically converted into dual high-k after the annealing process.

International audience; This study deals with the growth mode of N,N’-dipenthyl-3,4,9,10-perylenetetracarboxylic diimide(PTCDI-5C) thin films from less than one monolayer to 23 monolayers thick. The effects of growthtemperature and the thickness and nature of the substrates —SiO 2 on Si(001) oroctadecyltrichlorosilane (OTS) self-assembled monolayer terminated Si(001) surfaces— arediscussed. Thin films were deposited from a home-made Knudsen cell by using a hot-walldeposition technique. Films were analyzed by atomic force microscopy, X-ray diffraction, and X-rayreflectivity. Films exhibited a (001) orientation with a 1.63 nm d spacing, and a metastable thin filmphase was observed without any distinction of the nature of the substrate. However, differences werenoticed in the early stages of growth: PTCDI-5C/SiO 2 first monolayers presented a Stranski-Krastanov growth mode, whereas PTCDI-5C/OTS first monolayers showed a more complex mode with incomplete wetting of the substrate surface. Differences between the two morphologiessoftened as the film thickness increased.

The characteristic oxygen diffusion in HfO2∕SiO2∕Si structure during the annealing in oxygen has been investigated by high-resolution Rutherford backscattering spectroscopy in combination with oxygen isotope substitution at 900°C in 0.1Torr O218. The observed O18 profile suggests that oxygen molecules are decomposed into atomic oxygen in the HfO2 layer and diffuse through the oxide layer via exchange mechanism. This is also supported by the observed activation energy of ∼0.6eV for the growth of the interfacial SiO2 layer.

We propose a novel approach to control the effective workfunction (WF) by taking advantage of crystal structures in metal gate electrodes. The crystal structures determine the predominant material elements at the metal/high-k interface. We have found that, in a Ru-Mo alloy system, a randomly-oriented Ru (fcc) structure promotes the segregation of Mo at the interface, enabling us to achieve a wide controllability of flatband voltage (Vfb) from 0.6-0.8 eV In addition, the segregation of Mo within a Ru-rich electrode is a key to reducing Fermi level pinning at metal/HfSiON interfaces. Further tunability in Vfb has been examined by employing C-incorporation in the RuMo alloy, thus reducing the crystal grain size and facilitating the control of Vfb for a HfSiON (2 nm)/SiO2(0.7 nm)/Si capacitor. These results demonstrate that the crystal structure control in metal gates is essential for realizing the MIS-FET devices with a short gate length in the 32-22 nm node and beyond.

To investigate the influence of ionic/covalent interface of Al2O3/SiO2 gate insulator on the electrical properties of thin-film transistors (TFTs) with ionic Ga-In-Zn-O (GIZO) semiconducting channel layers, Al2O3 layers of different thickness were introduced between SiO2 and GIZO using plasma-enhanced atomic layer deposition. The GIZO layers were obtained by DC magnetron sputtering using a GIZO target (Ga:In:Zn = 1:1:1 mol. %). The GIZO TFTs with an Al2O3/SiO2 gate insulator exhibited positive threshold voltage (Vth) shift (about 1.1 V), Vth hysteresis suppression (0.23 V), and electron mobility degradation (about 13%) compared with those of a GIZO TFT with SiO2 gate insulator by the influence of ionic/ionic and ionic/covalent interface at Al2O3/GIZO and Al2O3/SiO2, respectively. To clarify the origin of the positive Vth shift, the authors estimated the shifts of flatband voltage (0.4 V) due to the dipole and the fixed charge (−1.1 × 1011/cm2) at Al2O3/SiO2 interface, from capacitance–voltage data for Pt/...

The passivation properties and band structures in aluminum oxide (AlOx) deposited by ozone-based atomic layer deposition (ALD) at room temperature on p-type crystalline silicon were investigated by X-ray photoelectron spectroscopy (XPS). The effective carrier lifetime depends on the thickness of AlOx films, since the field effects induced in the films by fixed charges depend on film thickness. The fixed charges are different by two orders of magnitude between films with thicknesses of 10 and 30 nm. At the 30-nm-thick AlOx/Si interface, the completely accumulated band bending of the Si surface was observed. On the other hand, a thin depletion layer was formed at the 10-nm-thick AlOx/Si interface. From the time-dependent XPS measurements, a hole trap was observed toward AlOx, in which trapping centers existed.

Recently, excellent surface passivation has been achieved for both p- and n-type silicon solar cells using AlOx/SiNx:H stacks deposited by atomic layer deposition and plasma-enhanced chemical vapor deposition. However, alternative materials and deposition methods could provide practical options for large-scale manufacturing of commercial solar cells. In this study we demonstrate that AlOx/AlNx stacks fabricated by reactive radio-frequency magnetron sputtering can provide fairly good surface passivation (Smax of ~30 cm/s) regardless of AlOx thickness, which is found to be due to the high negative fixed charge density (Qeff of −2.8 × 1012 cm−2) and moderately low interface trap density (Dit of 2.0 × 1011 eV−1cm−2). The stacks also show fairly good antireflection performance in the visible and near-infrared spectral region. The demonstrated surface passivation and antireflection performance of in situ reactively sputtered AlOx/AlNx stacks make them a promising candidate for a surface-passivating antireflection coating on silicon solar cells.

We established a process to develop well-defined polymer nanowire transistors made of liquid-crystalline semiconducting poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2). Nano-scaled channels have been fabricated in gate insulator layers of SiO2 using a lithography technique. The nanochannels offer templates for forming polymer nanowires in which polymer chains are uniaxially aligned along the nanochannels through a nano-confinement effect. In addition, this process prevents the occurrence of serious damage during the inevitable etching process that is used to separate the nanowires from each other. We examined the electrical properties and polymeric chain alignment of F8T2 nanowires. Nanowire transistors exhibited carrier mobilities of 3.5 and 2.8 × 10−3 cm2/Vs for 54 and 130 nm wide nanowires, respectively. The carrier mobilities were about three times larger than that of a thin film transistor. Polarized UV-vis absorption analysis clarified that the improved carrier mobility can be attributed to the enh...

Introduction Recently, thin-film transistor (TFT) with InOx-based metal oxide semiconductors such as Ga-In-Zn-O (GIZO) [1], In-Ga-O [2], In-Sn-O [3, 4], and In-Zn-O [5, 6] have attracted attention as high-speed switches for next-generation flat-panel display. However it remains a big issue of the anomalous oxygen vacancies (VO) formation, which destabilize the electronic properties. We have previously investigated In-Ti-O [7], In-W-O [7-9], and In-Si-O [7, 10] systems to suppress VObecause of high bond dissociated energies between each element and oxygen such as Ti-O (667 kJ/mol), W-O (720 kJ/mol), and Si-O (799 kJ/mol) [11]. Although C-O has the highest bond dissociated energies of 1076 kJ/mol [11], CO and CO2 are gases at standard ambient temperature and pressure. So we tried to fabricate carbon-doped In-Si-O (In1-xSixOC) semiconductor films using co-sputtering method with SiC and In2O3targets. In this paper, we investigated electrical and physical properties of In1-xSixOC films by the X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM) and hall measurement. Experiment A 100-nm-thick thermal SiO2 film was formed on a p-type Si substrate. Next, 50-nm-thick In1-xSixOC films were deposited on SiO2 film at room temperature by co-sputtering using In2O3 and SiC target under an Ar/O2 atmosphere at 0.2 Pa with various oxygen partial pressures (PO 2 = 0 ~ 0.08 Pa) at room temperature. The Si content (x=0.12 ~ 0.32) in In1-xSixOC films was controlled by changing DC the sputtering power of each target. Then, the post deposition annealing was performed at 250 ~ 600 °C for 1h in air. Finally, Au (100 nm)/ Ti (10 nm) electrodes were deposited by thermal evaporation method for hall measurement. The carbon content, structure and surface morphology of In1-xSixOC films were examined by XPS, XRD and AFM measurements, respectively. Results and Discussion Characteristics of the In1-xSixOC film Figure 1 shows AFM images of as-grown, 250 °C and 600 °C annealed In0.8Si0.2OC films. The root-mean-square (RMS) values of all samples show small values of 0.43~0.61 nm. We found that the In0.8Si0.2OC films have smooth surface even after annealing at a high temperature (600 °C). We also confirmed that the film was kept to be amorphous structure after annealing at 600 °C by XRD measurement. From the XPS measurement, a large C1s peak was observed due to Si-C bond at around 285 eV in as-grown and 250 °C annealed In0.8Si0.2OC films. This indicates that carbon sufficiently introduced into In-Si-O films using co-sputtering method with SiC target. Electrical properties of the In1-xSixOC film Figure 2 shows change of hall mobility and carrier concentration as a function of Si content in the In1-xSixOC films. Two kinds of the In1-xSixOC films were deposited under PO 2 0 and 0.08 Pa, and subsequently annealed at 250 °C. The mobility of the In1-xSixO and In1-xSixOC films fabricated under the same PO 2 = 0.08 Pa show a similar behavior. On the other hand, the mobility of the In0.88Si0.12OC and In0.8Si0.2OC films fabricated under PO 2 = 0 Pa shows about 5 - 8 times smaller than another one, respectively. Furthermore, the mobility and carrier concentration of both In1-xSixOC films decrease as Si content increases. This suggests that the VO formation into the In1-xSixOC films must be strongly influenced by the oxygen pressure during sputtering. Conclusions We studied characteristics of the In1-xSixOC films, which fabricated by co-sputtering method using SiC and In2O3 targets. We found that the In1-xSixOC film had an amorphous structure, smooth surface morphology and Si-C bond formation. The In1-xSixOC film is one of promising candidate as metal oxide channel materials because of high hall mobility of about 20. References [1] K. Nomura et al., Nature 432, 488 (2004). [2] K. Ebata et al., Appl. Phys. Express 5, 011102 (2012). [3] T. Miyasako et al., Appl. Phys. Lett. 86, 162902 (2005). [4] S. Y. Park et al., Appl. Phys. Lett. 100, 162108 (2012). [5] N. L. Dehuff et al., J. Appl. Phys. 97, 064505 (2005). [6] P. Barquinha et al., J. Non-Cryst. Solids 352, 1749 (2006). [7] S. Aikawa et al., Appl. Phys. Lett. 103, 172105 (2013). [8] S. Aikawa et al., Appl. Phys. Lett. 102, 102101 (2013). [9] T. Kizu et al., Appl. Phys. Lett. 104, 152103 (2014). [10] N. Mitoma et al., Appl. Phys. Lett. 104, 102103 (2014). [11] Y. R. Luo, “Bond dissociation energies,” in CRC Handbook of Chemistry and Physics, 90th ed.,edited by D. R. Lide (CRC Press/Taylor and Francis, Boca Raton, 2009). [12] S. Parthiban et al., RSC Adv. 4, 21958 (2014). Figure 1

An interconnect of flexible and foldable devices based on advanced electronics requires high electrical conductivity, flexibility, adhesiveness on a plastic substrate, and efficient productivity. In this study, we investigated the applicability of a conductive polymer/metal composite to the interconnect of flexible devices. By combining an inkjet process and a photochemical reaction, micropatterns of a polypyrrole/silver composite were formed on flexible plastic substrates with an average linewidth of approximately 70 µm within 10 min. The conductivity of the composite was improved to 6.0 × 102 Ω−1cm−1. From these results, it is expected that the conducting polymer/metal composite can be applied to the microwiring of flexible electronic devices.

The preparation of nonpolar ZnO and Cu-doped ZnO thin films on Si substrates was studied for the application to the fabrication of green-light-emitting diodes. The use of rocksalt MnS and wurtzite AlN as buffer layers is a key technology for achieving the heteroepitaxial growth of nonpolar ZnO thin film on a (100) Si substrate. X-ray diffraction and photoluminescence measurements revealed that deposition under a high oxygen partial pressure (~1 Torr) can enhance the nonpolar crystallization of undoped ZnO, and can simultaneously suppress the formation of defects such as oxygen vacancies. These techniques can be also applied to the growth of Cu-doped ZnO. A room-temperature photoluminescence study revealed that nonpolar -oriented Cu-doped ZnO film exhibits enhanced green emission owing to the doped Cu ions.

The Cu ion migration behavior of a Pt/Cu/HfO2/Pt structure, which is an oxide-based resistive random access memory (ReRAM) and exhibits resistance switching behavior at voltages of ±0.8 V, was investigated by hard X-ray photoelectron spectroscopy under a bias operation. A forward bias application, during switching from a high resistive state (HRS) to a low resistive state, reduced the Cu2O bonding state at the interface and the intensity ratio of Cu 2p3/2/Hf 3d5/2 (Cu/Hf) by 23 ± 5%, providing evidence of reductions in unintentionally formed Cu2O and Cu diffusion into the HfO2 layer. After switching to HRS again, Cu/Hf increased by 15 ± 5%, indicating that the Cu ion moved back to the top electrode side, though oxygen showed no bias voltage dependence. Consequently, the Cu ion has a key role in the switching. We directly observed the Cu migration behavior related to the resistive change at the Cu/HfO2 interface under bias operation.

Combinatorial thin-film of (1−x)[BaTiO3]–x[Bi(Mg2/3Nb1/3)O3] — (BT–BMN) was grown on Pt/Ti/SiO2/Si, using pulse laser deposition (PLD) method, by ablating stoichiometric and Bi-10 wt % enriched targets to optimize the Bi content. X-ray photoelectron spectroscopy analysis revealed a linear Bi composition spread. As-deposited films post-annealed at high-temperatures, under oxygen atmosphere, turned into crystalline state. The crystallinity, characterized by X-ray diffraction, is better towards Bi-enriched region. The dielectric constant showed a strong dependency of Bi composition and saturated over Bi-7 wt %. The scanning nonlinear dielectric microscopic investigation revealed ferroelectric phase distribution is better around Bi-7 wt % region where the measured leakage current is also minimum. Dielectric constant over 240 and dielectric constant stability below 13% (25–400 °C range) were obtained.

Floating-gate (FG)-type three-dimensional (3D) fin channel flash memories with triangular fin (TF) and rectangular fin (RF) channels and different interpoly dielectric (IPD) materials have been successfully fabricated using (100)- and (110)-oriented silicon-on-insulator (SOI) wafers and orientation-dependent wet etching. The electrical characteristics of the fabricated FG-type 3D fin channel flash memories including threshold voltage (Vt) variability, program/erase (P/E) speed, memory window, endurance, and data retention at room temperature and 85 °C have been comparatively investigated. A higher P/E speed, a larger memory window, and a lower-voltage operation are experimentally obtained in the TF channel flash memories with an Al2O3–nitride–oxide (ANO) IPD layer (TF-ANO) than in the RF channel ones with the same ANO IPD layer (RF-ANO) and the TF channel ones with an oxide–nitride–oxide (ONO) IPD layer (TF-ONO). The larger memory window and lower-voltage operation of TF-ANO flash memories are due to the high-k effect of the Al2O3 layer and the electric field enhancement at the sharp foot edges of the TF channels. It was also found that data retention for all fabricated FG-type 3D fin channel flash memories shows a weak dependence on temperature.

The epitaxial growth of 0.6[BaTiO3]–0.4[Bi(Mg2/3Nb1/3)O3] (BT–BMN) relaxor ferroelectric thin-films on (100) Nb doped SrTiO3 substrates has been achieved and the structure is investigated for high-temperature capacitor applications. The post growth annealing decreases the oxygen vacancy and other defects in BT–BMN films, resulting in the enhancement of dielectric constant. An insertion of intermediate SrRuO3 layers as an electrode instead of Pt, sandwiching the film, is found to be more effective in enhancing the dielectric constant. A very high dielectric constant exceeding 400 was achieved from high-temperature annealed film and the film showed an excellent dielectric constant stability of below 11% in the temperature range of 80–400 °C. This will enable smaller, high-temperature tolerant, monolithically integrated thin-film capacitors on power semiconductor devices.

A novel technique for the control of nitrogen (N) and oxygen (O) concentrations in the metal/high-k gate stacks is proposed. By inserting a reactive metal (Ti) layer remote from work function metal and high-k insulator, N and O concentration is easily decreased. This technique effectively suppresses the EOT increase after high-temperature annealing. Moreover, improved electron mobility and decreased interfacial trap density can be obtained by this technique. We demonstrated MISFET with extremely high electron mobility and thin EOT can be easily obtained even with relaxed process of HfSiON

Fermi-level pinning of poly-Si and metal-silicide gate materials on Hf-based gate dielectrics has been systematically studied theoretically. Fermi-level pinning in high-work-function materials is governed by the O vacancy generation and subsequent formation of interface dipoles near gate electrodes due to the electron transfer. On the other hand, O interstitial formation plays a crucial role for Fermi-level pinning in low-work-function materials. From our theoretical considerations, we have found that the work-function pinning-free-region generally appears due the difference in the mechanism of Fermi-level pinning of high- and low-work-function materials. The widening of this work-function pinning-free-region is the key issue for the fundamental relaxation of Fermi-level pinning in high-k gate dielectric

An orbital-dependent nonlocal correlation energy functional has been derived from an energy formula defined in the transcorrelated method. The obtained functional explicitly depends on a Jastrow function, which has been successfully used for the electron gas and solids. We found that our correlation energy functional is successfully used with the exact exchange energy functional and gives relatively good estimates for the total energy and the ionization potential for atoms and ions.

Flux-mediated epitaxy has been developed for ferroelectric Bi4Ti3O12 single-crystal film growth, as shown on the inside cover. The key point is the selection of an appropriate flux material. A combinatorial high-throughput screening technique reported by Matsumoto and co-workers on p. 485 has led to the successful discovery of the novel flux composition, Bi–Cu–O, for Bi4Ti3O12 single-crystal film growth. This flux-mediated epitaxy is not limited to oxide epitaxy, but is also widely applicable to various promising materials for the realization of non-Si-based electronics, such as nitrides, carbides, and halides. Excellent crystallinity of material films and atomic control of their surface/interface, sufficient for the realization of their optimal physical properties, are technological premises for modern functional-device applications. Bi4Ti3O12 and related compounds attract much interest as highly insulating, ferroelectric materials for use in ferroelectric random-access memories. However, it has been difficult thus far for Bi4Ti3O12 films to satisfy such requirements when formed using vapor-phase epitaxy, owing to the high volatility of Bi in a vacuum. Here, we demonstrate that flux-mediated epitaxy is one of the most promising and widely applicable concepts to overcome this inevitable problem. The key point of this process is the appropriate selection of a multi-component flux system. A combinatorial approach has led to the successful discovery of the novel flux composition of Bi–Cu–O for Bi4Ti3O12 single-crystal film growth. The perfect single-crystal nature of the stoichiometric Bi4Ti3O12 film formed has been verified through its giant grain size and electric properties, equivalent to those of bulk single crystals. This demonstration has broad implications, opening up the possibility of preparing stoichiometric single-crystal oxide films via vapor-phase epitaxy, even if volatile constituents are required.

Compact Jastrow-Slater-type correlated wave functions for three- and four-electron atoms and ions (Li, ${\mathrm{Be}}^{+}$, ${\mathrm{B}}^{2+}$, ${\mathrm{C}}^{3+}$, Be, ${\mathrm{B}}^{+}$, and ${\mathrm{C}}^{2+}$) are proposed. The Jastrow factor we employed consists of one-body and two-body functions including only two variational parameters in total. We found that a one-body Jastrow function with one variational parameter, which is responsible for the screening effect around the nucleus, is effective for reproducing good total energies of the three- and four-electron atomic systems if hydrogenoid orbitals are adopted in the Slater determinant. On the other hand, a determinant composed of Hartree-Fock orbitals multiplied by the same Jastrow factor was found to give rather worse results than that composed of hydrogenoid orbitals. This result clearly indicates that analytic hydrogenoid orbitals coupled with the one-body Jastrow function are useful for describing simple wave functions and understanding the physical properties of these systems.

A combinatorial ternary composition spread method, which included continuous ternary and binary compositions, was applied for new materials exploration for the future gate stack structure, rapid estimation of permittivity are carried out by microwave microscope as well as conventional C-V measurement. Structural analyses are performed systematically by combinatorial X-ray diffraction equipment. Higher dielectric region are observed in (HfO2)x(Y2 O3)y(Al2O3)z and ternary composition area. Al2O3 was found to have an ability that prevents HfO2-Y2O 3 alloy from crystallization. the authors found that HfxYxAlzO ternary oxide is a candidate of stable amorphous high-k gate dielectric material with stable interface on Si substrate. The reason of this stability could be explained by charge neutrality based on the phase diagram which is concluded by thermodynamics