bluuebunny/crossref_metadata_2025_split huggingface dataset:
Materials Characterization and Synthesis of Conductive Aromatic-Bis(Benzothiazoles)
Authors: Alexander Max D. , Sankaran Balasubramanian , McKellar B. Robert , Dudis Douglas S. 
Published: April 2011

ABSTRACTFunctionalized aromatic-bis(benzothiazoles) have been synthesized by our group and have shown promise as conductive n-dopable polymers and oligomers. When reduced (n-doped) these materials typically exhibit conductivity on the order of tens of S/cm. Here we examine the material properties of this family of derivatized, conductive aromatic-bis(benzothiazoles). A variety of synthetic approaches have been examined to produce these polymers and oligomers, and will be discussed. Material characterization has been accomplished by spectro-electrochemistry, nuclear magnetic resonance (NMR), electron spin resonance (ESR), Fourier Transform Infrared (FTIR) spectroscopy, and direct current (DC) conductivity.
Electric Field Induced Self Assembly and Template Patterning of Polymer Microstructures
Authors: Ozkan Cengiz S. , Gao Huajian 
Published: April 2011

ABSTRACTWe have developed a method for fabricating polymer microstructures based on electric field induced self assembly and pattern formation. A dielectric fluid placed in between to conductive plates experiences a force in an applied electric field gradient across the plates, which can induce a diffusive surface instability and self construction of the fluid surface. This process is exploited for the fabrication of self assembled polymer microstructures as well as replicated patterns through the use of pre-patterned plates or electrodes. We have used silicon wafers and transparent ITO (Indium-Tin Oxide) coated quartz substrates to fabricate the capacitor structures. The bottom silicon plate is spin coated with a 100-200 nm thick polystyrene film. The ITO substrate was placed over the polymer surface at a distance to leave a thin air gap using spacers. For directed pattern transfer, patterned ITO substrates were used. The capacitor setup was heated above the glass transition temperature of the polymer and a voltage was applied across the plates (50-150 Volts), which induces electric fields on the order of 107–108 V/m. The capacitor structure was quenched to observe the structures using optical microscopy and atomic force microscopy. The method described can be used to fabricate a variety of structures in the micron and nanometer scales including bio-fluidic MEMS, polymer optoelectronic devices and patterned templates for nanolithography.
Conjugatged Oligomeric Coordinated Silver Phenylacetylide Derivatives With Ultrafast Optical Kerr Effect
Authors: Xu Y. H. , Teo B.K. , Wu H.M. , Guo S.L. , He Y.K. , Chen H.Y. , Qian W. , Wu S.J. , Zuo Y.H. 
Published: April 2011

ABSTRACTSilver phenylacetylide prepared by one-step process was characterized as a linear coordinated polymeric compound by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectroscopy. Its prominent third-order optical nonlinearity was detected by heterodyned ultrafast optical Kerr effect (OHD-OKE) measurement. The second-order hyperpolarizability was enhanced by 2 orders of magnitude by means of incorporation of proper electron-pushing groups. The structure status was further investigated by quantum chemical calculation and molecular modeling.
Thin Film Metal Oxide Semiconductors Deposited on Polymeric Substrates
Authors: Fortunato Elvira , Nunes Patrícia , Marques António , Costa Daniel , Águas Hugo , Ferreira Isabel , Costa Maria E. V. , Martins Rodrigo 
Published: April 2011

ABSTRACTHighly textured transparent conducting ZnO:Al thin films have been prepared by r.f. magnetron sputtering. The films were deposited on polyester (Mylar type D, 100 µm thickness) and glass substrates at room temperature. Surface stylus profiling, X-ray diffraction, scanning electron microscopy, transmission electron microscope and Hall effect measurements as a function of temperature have been used to characterize the produced films. The samples are polycrystalline with a hexagonal wurtzite structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface (columnar structure). The ZnO:Al thin films with a resistivity as low as 3.6×10−2 µcm have been obtained, as deposited.
Development Of Transparent Lsco and Lscno Conductors for Optical Shutter Systems
Authors: Schwartz R. W. , Sebastian M. T. , Charoenwongsa M. , Dobberstein H. 
Published: April 2011

ABSTRACTWe have prepared lanthanum strontium cobalt oxide (La0.50Sr0.50CoO3; LSCO 50/50) and lanthanum strontium cobalt nickel oxide (La0.50Sr0.50Co0.50Ni0.50O3; LSCNO) as candidate transparent electrodes for use in a shutter-based infrared sensor protection device. The shutter device requires that the electrode be transparent (80% transmission) and have moderate sheet resistance (300 ω/sq.). Because of the effects of film thickness on intrinsic material properties, such as resistivity and extinction coefficient, and simple engineering issues (i.e., the relationship between film thickness, resistance and transmission), films of various thicknesses were prepared to achieve an optimal balance of electrical and optical performance. van der Pauw measurements and FTIR spectroscopy were used to study thin film properties. The best LSCO films prepared demonstrated electrical (438 ω/sq.) and optical (68% transmission at 8 µm) properties that did not meet the target property goals for this application. However, the LSCNO films (of optimal thickness) offered performance (323 µ/sq. and 73% transmission) close to the device requirements.
Predominant Scattering Mechanism in Transparent Conductive Oxide Films
Authors: Meng Chen , Zhiliang Pei , Xi Wang , Cao Sun , Lishi Wen 
Published: April 2011

ABSTRACTContributions of acoustical deformation scattering, ion impurity scattering and grain boundary potential scattering to the conductivity of TCO films have been calculated to discuss the predominant scattering mechanism, regardless of precise details of the preparation procedure. The results indicate that the effective mass of charge carriers has a strong dependence on carrier concentration. Based on the effective mass correction, as well as the carrier concentration-ionized impurity centers correction, scattering due to ion impurity has been developed to explain the upper limit of mobility or the lower limit of resistivity of TCO films. Two empirical expressions are introduced to depict the dependence of the upper limit of mobility and the lower limit of resistivity of TCO films on carrier concentration.
Electrical Characteristics of the Pt/SBT/TiO2/Si MFIS Structures with Thickness Variation of the SBT Film
Authors: Kim Ji-Woong , Lee Kwang-Yong , Choi Jae-Hoon , Oh Tae-Sung 
Published: April 2011

ABSTRACTPt/Sr0.85Bi2.4Ta2O9/TiO2/Si structures were prepared with variation of the Sr0.85Bi2.4Ta2O9 (SBT) film thickness for MFIS-FET applications. After depositing TiO2 film of 10 nm thickness by reactive sputtering on Si(100) substrate as a buffer layer, SBT thin film of 210-400 nm thickness was prepared onto it by metal organic decomposition process. Regardless of the SBT film thickness, the Pt/SBT/TiO2/Si structures exhibited clockwise directional hysteresis, indicating well-defined ferroelectric switching behavior of the SBT films. While the memory window of the Pt/SBT/TiO2/Si MFIS structures increased with increasing the SBT film thickness, the maximum capacitance of the Pt/SBT/TiO2/Si MFIS structures decreased with increasing the SBT film thickness. The Pt/SBT(400 nm)/TiO2(10 nm)/Si structure exhibited a memory window of 1.3 V at ±5 V.
Doping Effects on CdO Thin Films
Authors: Li X. , Barnes T. , DeHart C. , King D. , Asher S. , Young M. , Gessert T.A. , Coutts T.J. 
Published: April 2011

ABSTRACTThis paper reports the properties of undoped CdO films and CdO films doped with the group VII element F and the group IV element Sn. The CdO films are made by low-pressure chemical-vapor deposition. We observe that undoped CdO films can achieve a carrier concentration of 1021 cm−3, apparently by controlling the intrinsic defect. However, the electron mobility of these films is only around 2 cm2 V−1 s−1. With fluorine doping, an electron mobility of ∼260 cm2 V−1 s−1 has been achieved. However, low carrier concentration results because of the low solubility of F in CdO film. CdO films doped with both Sn and F demonstrate carrier concentrations of 1021 cm−3 and reasonable electron mobilities of around 20 cm2 V−1 s−1. Due to the small effective electron mass of CdO, a large Burstein-Moss shift is observed for films with high carrier concentration. The shift enables the fundamental absorption edges of undoped CdO films to reach 3.0 eV and 3.3 eV for films doped with both Sn and F.
The Mechanical Reliability of Sputter-Coated Indium Tin Oxide Polyester Substrates for Flexible Display and Touchscreen Applications
Authors: Cairns Darran R. , Paine David C. , Crawford Gregory P. 
Published: April 2011

ABSTRACTIndium tin oxide (ITO) films deposited on polyester substrates are a key material in the development of two exciting technologies, touchscreens and flexible liquid crystal displays. The new generation “plastic” displays and touchscreens must be flexible and robust, have excellent optical properties, and be inexpensive. We report on the mechanical and electrical reliability of ITO on a polyethylene terephthalate substrate (PET). We show that the mechanical behavior of the ITO film is dominated by the properties of the substrate and that the deformation of the substrate is mapped by the crack patterns in the ITO. This is most strongly evidenced in the simulated wear of a touchscreen where failure after >50000 pen strokes is primarily due to cracking of the ITO as a result of increased substrate deformation over time. In addition the mechanical reliability of the ITO layer is dependent on the film thickness. Cracking was observed in a 105 nm thick ITO film at a strain of 0.022 and for a 16.8 nm thick film at 0.003. The thickness and hence sheet resistance of the film effectively limits the maximum allowable deformation of the substrate and must be considered in the design of suitable display and touchscreen devices. In addition we report on the change in resistance with time-at- temperature and relate this to the shrinkage of the substrate.
Dielectric Properties and Leakage Current Characteristics of Al2O3 Thin Films with Thickness Variation
Authors: Choi Jae-Hoon , Kim Ji-Woong , Oh Tae-Sung 
Published: April 2011

ABSTRACTDielectric properties and leakage current characteristics of the Al2O3 thin films, deposited by reactive sputtering at room temperature, have been investigated with variations of the O2 content in the sputtering gas and the film thickness. The Al2O3 films of 10-300 nm thickness were amorphous without depending on the O2 contents of 25-75% in the sputtering gas. Maximum dielectric constant was obtained for the Al2O3 film deposited with the sputtering gas of 50% O2 content. With reduction of the film thickness from 300 nm to 10 nm, dielectric constant decreased from 9.04 to 3.71 and tangent loss increased from 0.0035 to 0.0594, respectively. When the O2 content in the sputtering gas was higher than 50%, the Al2O3 films exhibited no shift of the flatband voltage in C-V curves. The leakage current density increased with increasing the film thickness, and the Al2O3 films thinner than 100 nm exhibited the leakage current densities lower than 10−6 A/cm up to 650 kV/cm.
Thin film combustible gas sensors based on Zinc Oxide
Authors: Nunes Patrícia , Fortunato Elvira 
Published: April 2011

ABSTRACTSensitivity tests to reductive gases such as methane, hydrogen and ethane were performed on zinc oxide (ZnO) thin films. The highest value of sensitivity was obtained for the film with a high electrical resistivity and a low thickness. The variation of the operating temperature of the film leads to a significant change in the sensitivity of the sensor with an ideal operating temperature dependence of the gas used. The sensitivity of the ZnO thin films changes linear with the increase of the gas concentration. However these films seem to be more appropriated for the detection of hydrogen following by methane and than for ethane since the value of sensitivity obtained are higher and its variation with the gas concentration more pronounced.
Integration of Biaxially Aligned Conducting Oxides with Silicon using Ion-Beam Assisted Deposited MgO Templates
Authors: Emmert Luke A. , Park Bae-Ho , Groves James R. , DePaula Raymond F. , Jia Q.X. , Arendt Paul N. 
Published: April 2011

ABSTRACTTwo conducting oxides, La0.5Sr0.5CoO3(LSCO) and SrRuO3, were deposited by pulsed laser ablation onto silicon substrates coated with biaxially textured MgO on an amorphous silicon nitride isolation layer. Comparison is made between templates using just 10 nm of ion-beam assisted deposited (IBAD) MgO and substrates with an additional 100 nm of homoepitaxial MgO. Both of these conducting oxide layers exhibited in-plane and out-of-plane texture, on the order of that obtained by the underlying MgO. The SrRuO3 was c-axis oriented on both substrates, but exhibited a slightly sharper out-of- plane texture when the homoepitaxial MgO layer was included. On the other hand, the LSCO showed only (100) orientation when deposited directly on the IBAD-MgO templates, whereas a significant (110) peak was observed for films on the homoepitaxial MgO. A simple calculation of the distribution of grain boundary angles, assuming a normal distribution of grains, is also presented.
Domain structure in LaFeO3 thin films and its role on exchange coupling
Authors: Seo Jin Won , Fompeyrine Jean , Siegwart Heinz , Locquet Jean-Pierre 
Published: April 2011

ABSTRACTThe origin of the exchange bias between a ferro- and an antiferromagnet still is not fully resolved. Many structural parameters such as film thickness, roughness, domain size, domain walls, strain, dislocations, and surface defects play a role. To disentangle their individual contributions, one must correlate each of these structural effects with the exchange bias. Here we report our first such attempts using thin films of the antiferromagnetic orthoferrite LaFeO3 grown by molecular beam epitaxy. We investigate how the epitaxial relationship and strain affect the domain configuration as well as their size and orientation. Next, we explore how these different domains can pin ferromagnetic domains in exchange-coupled systems. We conclude that decreasing the domain size of the antiferromagnet leads to a higher exchange bias. The highest exchange bias was obtained for LaFeO3 films on MgO substrates.
Electronic Structures and Nature of Host Excitation in Gallates
Authors: Schmidt P. C. , Sticht J. , Stephan M. , Eyert V. , Mishra K. C. 
Published: April 2011

ABSTRACTIt is an interesting exercise in materials science to explore simple rules relating the electronic properties of ternary systems to those of their binary constituents. In the present work, we have investigated the electronic structures of the large band gap gallates MGa2O4(M=Mg, Ca, Ba and Zn) and the corresponding binary oxides MO and Ga2O3. Using first-principles band structure methods, we find that the metal atoms in MO control the width of the O 2p-like valence band and the size of the optical band gap. Covalent metal-oxygen bonding is much more pronounced in Ga2O3 and leads to characteristic structure in the valence band density of states. These basic features are retained in the ternary compounds where the covalent admixture to the chemical bond is largest between Ga and O, and the transitions across the band gap involve the Ga2O3 sublattice.
Cerium Doped Garnet Phosphors for Application in White GaN-based LEDs
Authors: Wu Jennifer L. , Denbaars Steven P. , Srdanov Vojislav , Weinberg Henry 
Published: April 2011

ABSTRACTRecently, renewed interest has emerged for the development of visible light, down-converting phosphors for application in white light emitting diodes (LEDs). In such devices, a blue GaN LED can act as a primary light source, serving as an efficient pump to excite photoluminescence in a phosphor with subsequent emission occurring at lower energies. The combination of blue light from the LED chip and emission from the phosphor(s) produces white light. It was recently reported that a combinatorial approach to synthesize and screen potential inorganic phosphors for use in white LEDs could aid in identifying improved phosphors for blue to yellow down conversion. Solid state thin-film arrays (libraries) based on the garnet structure (A1−x,Bx)3−z(C1−y,Dy)5O12:Ce3+z, where A, B = Y, Gd, Lu, La; C., D = Al, Ga; x and y = 0 to 1.0; and z = 0.03, were synthesized, and x-ray diffraction was used to select library samples of the crystalline garnet phase. Libraries of these various garnets were then characterized spectroscopically and their properties compared to traditionally prepared bulk powder phosphors of similar composition. Emission and excitation trends show that as larger cations are substituted for Y (A = Y), emission and excitation are red-shifted and as larger cations are substituted for Al (C = Al), emission and excitation are blue-shifted. If smaller cations are substituted for Y and Al an opposite trend is observed. Temperature dependence photoluminescence measurements and emission/excitation trends are also examined.
Synthesis and optical characteristics of ZnGa2O4−xSx:Mn2+
Authors: Kim J.S. , Park H.L. , Kim G.C. 
Published: April 2011

ABSTRACTThe first zinc gallium oxysulfides (ZnGa2O4−xSx) are synthesized and emission properties of ZnGa2O4−xSxand ZnGa2O4−xSx:Mn2+have been investigated. The sulfur in ZnGa2O4−xSxforms tetrahedrons and the cations in ZnGa2O4−xSxare randomly distributed between tetrahedrons and octahedrons such that ZnGa2O4structure can be viewed as a mixed spinel. The four-fold enhancement of the brightness of Mn2+emission can be the significant effect of forming oxysulfide in ZnGa2O4−xSx:Mn2+
Long-Term Cathodoluminescent Characterization of Thin-Film Oxide Phosphors in a Wide Range of Electron Excitation Densities
Authors: Bondar Vyacheslav D. , Felter Thomas E. , Hunt Charles E. , Dubov Yuri G. , Chakhovskoi Andrei G. 
Published: April 2011

ABSTRACTLong-term processes of cathodoluminescence degradation of thin film phosphors Zn2SiO4:Ti and Zn2GeO4:Mn were investigated in a wide range of e-beam energies, current and power densities. The time dependencies describing the decreasing of emission intensity have been found. At higher current densities of e-beam irradiation, the specific behavior of long-term degradation processes was observed, which is characterized by rapid initial degradation and a slower long term decrease. The most probable mechanisms are proposed for long-term processes of degradation in the investigated phosphors.
SPV Monitoring of Near Surface Doping – Role of Boron-Hydrogen Interaction; Boron Passivation and Reactivation
Authors: Marinskiy D. , Lagowski J. 
Published: April 2011

ABSTRACTHydrogen is known to cause the passivation of boron acceptors after such processing steps as wet etching, reactive ion etching, sputter deposition of metal contacts, and Ar ion beam etching. Previous studies of this effect employed CV profiling, spreading resistance profiling, and SIMS measurements on samples diffused with deuterium. These methods are either destructive to the Si surface or require deposition of metal contact. In the present study we used a non-contact small signal ac-surface photovoltage technique, currentlyavailable in commercial diagnostic tools. Simultaneous measurements of the semiconductor surface barrier, Vsb, and the capacitance of the surface depletion layer, CD, give the concentration of boron acceptors in a submicron distance from the Si surface or Si/SiO2 interface. The technique has proven very successful in monitoring low dose implants and also near surface doping in oxidized wafers. Inbare silicon wafers the method occasionally indicated surface boron concentration noticeably below the bulk value. We found such behavior in wafers after the chemical cleaning, used to prepare a hydrogen terminated surface. Thermal annealing at temperatures from 150°C to 200°C reactivates the boron dopant. We will discuss the effect of various cleaning and annealing conditions on passivation and reactivation of boron acceptors in the near surface region. The results obtained with the non-contact SPV technique show excellent agreement with previous studies. They also provide a basis for reliable measurement of the boron concentration free of interference from hydrogen passivation.
Shallow Junctions for Sub-100 Nm Cmos Technology
Authors: Meyssen Veerle , Stolk Peter , van Zijl Jeroen , van Berkum Jurgen , van de Wijgert Willem , Lindsay Richard , Dachs Charles , Mannino Giovanni , Cowern Nick 
Published: April 2011

ABSTRACTThis paper studies the use of ion implantation and rapid thermal annealing for the fabrication of shallow junctions in sub-100 nm CMOS technology. Spike annealing recipes were optimized on the basis of delta-doping diffusion experiments and shallow junction characteristics. In addition, using GeF2 pre-amorphization implants in combination with low-energy BF2 and spike annealing, p-type junctions depths of 30 nm were obtained with sheet resistances as low as 390 Ω/sq. The combined finetuning of implantation and annealing conditions is expected to enable junction scaling into the 70-nm CMOS technology node.
The Role of Ion Mass on End-of-Range Damage in Shallow Preamorphizing Silicon
Authors: Clark Mark H. , Jones Kevin S. , Haynes Tony E. , Barbour Charles J. , Minor Kenneth G. , Andideh Ebrahim 
Published: April 2011

ABSTRACTPreamorphization is commonly used to form shallow junction in silicon CMOS devices. The purposeof this experiment was to study the effect of the preamorphizing species' mass on the interstitial concentration at the end-of-range (EOR). Isovalent species of Si, Ge, Sn and Pb were compared. Silicon wafers with a buried boron marker layer (4700 Å deep) were amorphized using implants of 22 keV 28Si+, 32 keV73Ge+, 40 keV 119Sn+ or 45 keV 207Pb+, which resulted in similar amorphous layer depths. All species were implanted at a dose of 5×1014 /cm2. Cross-sectional transmission electron microscopy (XTEM) was used tomeasure amorphous layer depths (approximately 400 Å). Post-implantation anneals were performed at 750 °C for 15 minutes. Plan-view transmission electron microscopy (PTEM) was used to observe and quantify the EOR defect population upon annealing. Secondary ion mass spectrometry (SIMS) was used to monitor the transient enhanced diffusion (TED) of the buried boron marker layer resulting from the EOR damage introduced by the amorphizing implants. Based upon the SIMS results Florida Object Oriented Process Simulator (FLOOPS) calculated the resulting time average diffusivity enhancements. Results showed that increasing the ion mass over a significant range (28 to 207 AMU) not only affects the quantity and type of damage that occurs at the EOR, but results in a reduced diffusivity enhancement.
Nonmelt Laser Annealing of 1 Kev Boron Implanted Silicon
Authors: Earles Susan , Law Mark , Jones Kevin , Talwar Somit , Corcoran Sean 
Published: April 2011

ABSTRACTHeavily-doped, ultra-shallow junctions in boron implanted silicon using pulsed laser annealing have been created. Laser energy in the nonmelt regime has been supplied to the silicon surface at a ramp rategreater than 1010°C/sec. This rapid ramp rate will help decrease dopant diffusion while supplying enough energy to the surface to produce dopant activation. High-dose, non-amorphizing 1 keV, 1e15 ions/cm2 boron is used. Four-point probe measurements (FPP) show a drop in sheet resistance withnonmelt laser annealing (NLA) alone. Transmission electron microscopy (TEM) shows the NLA dramatically affects the defect nucleation resulting in fewer defects with post annealing. Hall mobility and secondary ion mass spectroscopy (SIMS) results are also shown.