bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sequential Growth of High Quality Diamond Films from Hydrocarbon and Hydrogen Gases
Authors: Olson Darin S. , Kelly Michael A. , Kapoor Sanjiv , Hagstrom Stig B. 
Published: March 2011

ABSTRACTWe have constructed a novel, sequential DC glow and hot filament CVD reactor, to study the influence of single parameters on the deposition of diamond thin films. This reactor is capable of growing diamond films, with independent excitation of hydrogen and methane. This is achieved by the sequential exposure of the substrate to spatially separated, chemically independent, plasma regions of hydrogen, and methane in helium. The substrate is mounted on a rotating plate above the gas sources at a variable distance, typically 0.5 – 2 mm. The plate is radiantly heated from behind to a desired temperature up to 1300 K. Using the sequential deposition chamber we have been able to deposit good quality diamond up to 8% methane in helium, without the presence of oxygen, by separating a source of atomic hydrogen and a source of methane. These experiments show that methane and atomic hydrogen do not need to be present simultaneously to grow diamond. Our results further indicate that the primary critical parameter for both quality and growth rate, in hot filament deposition of diamond, is the concentration of atomic hydrogen in the system.
Mombe Growth of GaP and its Efficient Photoeniiancement at Low Temperatures
Authors: Yoshimoto Masahiro , Tsuji Tsuzumi , Kajimoto Atsushi , Matsunami Hiroyuki 
Published: March 2011

ABSTRACTGaP epllayers grown at temperatures ranging from 420 to 500°C had smooth surfaces and streaky RHEED patterns. The decomposition of group-III sources of TEGa limits the growth rates of GaP at lower substrate temperatures(<390 °C ). The growth rate of GaP epitaxial layers was efficiently enhanced by N2∼laser irradiation at lower substrate temperatures.
The Origin of Polytypes in SiC and ZnS
Authors: Heine Volker , Cheng C. , Engel C. E. , Needs R. J. 
Published: March 2011

ABSTRACTBoth SiC and ZnS exist in the cubic diamond-like (zinc blende) structure. A polytype is derived from the cubic stacking of atomic double layers by having a regularly repeated pattern of stacking faults. Dozens of such polytypes are known for SiC and ZnS.A study with several co-workers has been completed into the origin of this phenomenon. Are the polytypes genuine stable phases frozen in from some higher equilibrium temperature? Or are they inherently metastable structures born of some growth mechanism?Quantum mechanical calculations have shown that SiC polytypes formed from bands of 2 and 3 cubically stacked layers have a lower energy than other structures, in particular lower than the cubic or wurtzite structures. That already suggests that the polytypes can be stable phases. Further calculations of the phonon free energy and relaxation of the bond lengths rounds out the phase diagram. In this connection it is somewhat surprising that the material normally grows initially in the metastable cubic modification, transforming subsequently to a mixture of polytypes, but the calculations also suggest why this is so.The answers for ZnS turn out to be different from those for SiC.
Effect of Carbonization Gas Precursor on the Heteroepitaxial Growth of Sic-on-Si by Rtcvd
Authors: Steckl A. J. , Li J. P. 
Published: March 2011

ABSTRACTA comparison of several simple hydrocarbon gases, with H:C ratios ranging from 1 to 4, as precursors for the carbonization of Si is presented. The growth experiments were performed by RTCVD at reactor pressures of 760 and 5 Torr. For AP-RTCVD, we have found that C3H8, C2H4 and C2H2 have very similar dependence of growth rate on hydrocarbon partial pressure in the chamber. At 1300°C, this involved a maximum in film thickness being obtained at a hydrocarbon flow rate of 8–10 seem, representing a transition hydrocarbon fraction (in H2) of ∼ 5×10-4. CH4 carbonization produces a peak growth rate at a significantly higher fraction, ∼ 4×10-3. For LP-CVD at 5 Torr, the transition carbonization fraction increases by approximately an order of magnitude. The AP-RTCVD carbonization activation energy for C3H8, C2H4 and C2H2 at higher temperatures (∼1200–1300°C) has a common value of ∼ 0.8 eV, while for lower temperatures it depends on the hydrocarbon.
Characterization of Silicon Carbide thin Films Deposited by Laser Ablation on [001] and [111] Silicon Wafers
Authors: Rimai L. , Agar R. , Logothetis E. M. , Weber W. H. , Hangas J. 
Published: March 2011

ABSTRACTStoichiometric films of 3C SiC, 50 to 1000 nm thick were deposited on Si wafers by laser ablation of ceramic stoichiometric SiC targets. Films grown at substrate temperatures above 1000° C on [001] and above 900° C on [111] show orientation epitaxial to the Si substrate along the film normal. Depending on the deposition conditions, the oriented crystallite dimension along this direction ranges from 20 nm to over 100 nm. The crystallite dimensions in the film plane range from 20 to 70 nm. Raman spectra show the expected TO and LO lines from SiC but indicate that the films sometimes contain other material, for example (30 to 50 Å) graphitic inclusions or small amounts of polycrystalline silicon.
High Temperature Ohmie Contacts for N-Tvpe Β-Sic Sensors
Authors: Sho J. S. , Weber R. A. , Provost L. G. , Goldstein D. , Kurtz A. D. 
Published: March 2011

ABSTRACTIn order to fabricate high temperature sensors and other devices, it is necessary to develop ohmic contact metallizations that can withstand elevated temperatures. A variety of ohmic contact metallizations were investigated with contact resistivity measured as a function of anneal time in air. The metallizations were based on Ti and W ohmic contacts, which have contact resistivities as low as 10-4 Ω-cm2. Several of the contact metallizations were stable after 10 hrs. at 650°C, while one system, based on a Ti ohmic contact, was able to withstand > 20 hrs. at 650°C with only a 30–40% increase in contact resistivity.
Characterization of Boron Carbide Films Formed by PECVD
Authors: Mazurowski John , Lee Sunwoo , Ramseyer G. , Dowben P. A. 
Published: March 2011

ABSTRACTBoron carbide films have been fabricated from pentaborane (B5H9) and methane using plasma enhanced chemical vapor deposition (PECVD). Availability of high quality specimens has facilitated analysis of electronic and optical properties. We have undertaken measurements of photoluminescence spectra and infra-red band-edge absorption. Results show that the bandgap is strongly influenced by the ratio of boron to carbon. There is evidence for the existence of shallow trapping levels.
Amorphous and Microcrystalline SiC as New Synthetic Wide Gap Semiconductors
Authors: Hamakawa Y. , Okamoto H. 
Published: March 2011

ABSTRACTA review is given on recent progress in amorphous and microcrystalline silicon-carbide (a-SiC, nc-SiC) semiconductors and their technological applications to optoelectronic functional devices. Firstly, some significant properties in this alloy as a new synthetic material are pointed out with recent advances of thin film technologies, such as plasma CVD, ECR-CVD and ion-beam CVD etc. There exists an energy gap controllability from 1.7eV to 3.6 eV with retaining the valency electron control from n-type through i- to p-type semiconductors. While its conductivity can also be controlled more than ten order of magnitudes, e.g., from 10-9to 102 Scm-1 by controlling the impurity doping and preparation conditions.Secondly, a series of technical data on the electronic and optoelectronic properties of a-Si, C1−x C1−x and μ-SiC are demonstrated from recent achievements. In the final part of the paper, current state of the art in the field of optoelectronic applications from live technologies on amorphous silicon solar cells. a-SiC visible light LED and EL devices are reviewed. A technological evolution from “microelectronics” to “macroelectronlcs” will be discussed.
Structure, Characteristics, and the Application of Phosphorus Doped Hydrogenated Microcrystalline Silicon
Authors: Jeng S. J. , Kotecki D. E. , Kanicki J. , Parks C. C. , Tien J. 
Published: March 2011

ABSTRACTThe microstructure, electrical, and optical properties of in situ phosphorus doped hydrogenated macrocrystalline silicon (μc-Si:H:P) films are strongly affected by deposition parameters and subsequent thermal processes. μc-Si:H:P films with thickness ranging Trom 200 to lOOOÅ have been deposited on Si and SiO2 substrates. The μc-Si:H:P film is best deposited at 200°C in terms of structure, and H and P content. In this film, microcrystallites arc embedded in an amorphous matrix and have a volume fraction of ≃85%. The band-gap of the film is 1.8 eV. In this paper, the materials and processing issues of μc-Si:H:P deposited in a parallel plate RF plasma and in a downstream RF plasma chemical deposition reactor have been studied using HRTEM, SIMS, electrical, and optical measurements.
Lattice-Matched Heteroepitaxy of Wide Gap Ternary Compound Semiconductors
Authors: Bachmann Klaus J. 
Published: March 2011

ABSTRACTA variety of applications are identified for heteroepitaxial structures of wide gap I-III-VI2and II-IV-V2semiconductors, and are assessed in comparison with ternary III-V alloys and other wide gap materials. Non-linear optical applications of the I-III-VI2and II-IV-V2compound heterostructures are discussed, which require the growth of thick epitaxial layers imposing stringent requirements on the conditions of heteroepitaxy. In particular, recent results concerning the MOCVD growth of ZnSixGe1-xP2alloys lattice-matching Si or GaP substrates are reviewed. Also, heterostructures of CuzAg1-zGaS2alloys that lattice-match Si, Ge, GaP or GaAs substrates are considered in the context of optoelectronic devices operating in the blue wavelength regime. Since under the conditions of MOCVD, metastable alloys of the II-IV-V2compounds and group IV elements are realized, II-IV-V2alloys may also serve as interlayers in the integration of silicon and germanium with exactly lattice-matched tetrahedrally coordinated compound semiconductors, e.g. ZnSixGe1-xP2.
Chemical Vapor Deposition of Highly Transparent and Conductive Boron Doped Zinc Oxide Thin Films
Authors: Hu Jianhua , Gordon Roy G. 
Published: March 2011

ABSTRACTBoron doped zinc oxide films have been successfully deposited from a gas mixture of 0.05% diethyl zinc, 2.3% ethanol and various diborane concentrations in the temperature range 300°C to 430°C in an atmospheric pressure chemical vapor deposition reactor. The dopant diborane was found to decrease the film growth rate. The crystallite sizes of doped films were smaller than those of undoped films. Hall coefficient and resistance measurements at room temperatures gave conductivities between 250 and 1700 Ω-1, electron densities between 1.4×1020 and 6.7×1020 cm-3, and mobilities between 7 and 23 cm2/V-s. Optical measurements showed that a film with a sheet resistance of 8.8 Ω/square has an average visible absorption of about 8% and maximum infrared reflectance close to 85%. The ratio of conductivity to absorption coefficient is between 0.05 Ω-1 and 0.55 Ω-1. The band gap of doped film was widened and followed the Burstein-Moss relation.
Influence of Geometrical Parameters on the Electrical Properties of Ferroelectric Thin Films
Authors: Faure S.P. , Gaucher P. , Ganne J.P. 
Published: March 2011

AbstractFerroelectric thin films of PbZr0.5Ti0.5O3 were prepared by sol-gel process. Top electrodes of different sizes were deposited on thin films in order to study their influence on electrical properties. Histograms of the measured electrical characteristics are related to the electrode sizes. By reducing the electrode size, it is possible to improve the electrical properties of the film. Various properties, such as remanent polarization Pr and coercive voltage Vc, were measured statistically in order to show the evolution of their mean value and of their variance with the electrode size.
Polarization Dependent Conductivity in Thin Film Pzt Capacitors
Authors: Bernacki Stephen E. 
Published: March 2011

AbstractPolarization dependent conductivity is a dependence of the low field non switching steady state conduction current through a metal ferroelectric metal (MFM) thin film capacitor on the remanent polarization state of the capacitor. This paper proposes a simple theoretical model based on Schottky barrier formation due to PZT-platinum work function differences and barrier height modulation due to remanent polarization. The model predicts a conduction current dependence on both remanent polarization state and electrode material. Finally, we present experimental data in qualitative agreement with the model.
Optical Spectroscopic Profiling of Off-Axis Rf Sputtering
Authors: Klein J. D. , Yen A. 
Published: March 2011

AbstractThe optical emission spectra resulting from if magnetron sputtering a BaTiO3 target were observed to survey substrate position implications. A collimated optical fiber bundle parallel to the plane of the sputter target was translated vertically and horizontally to spectroscopically profile the sputter process. The resulting Ar, O, Ba, and Ti emission intensity contours and the O/Ba and Ba/Ti intensity ratio contours suggest substrate positions that should provide uniform undistorted films. Films deposited on sapphire substrates were found to differ in orientation, lattice parameter, and index of refraction. The optimum offaxis deposition position shifted as the chamber pressure was varied.
Physicochemical Properties of Rf Magnetron Sputtered Lead Zirconate Titanate Thin Films
Authors: Catitan E. , Agius B. , Achard H. , Joly J.P. , Cheang Wong J.C. , Ortega C. , Siejka J. 
Published: March 2011

AbstractLead zirconate titanate thin films have been grown by rf magnetron sputtering an oxide target of nominal composition [Pb(Zr0.55,Ti0.45)O3 or PZT] in argon. The kinetics of the sputtering process and the effect of sputtering parameters on film composition have been studied and related to the continuously monitored optical emission of the plasma. The relative and absolute cation and oxygen compositions of the thin films were determined by a new method based on the simultaneous use of Rutherford backscattering spectroscopy (RBS) and nuclear reaction analysis (NRA) induced by a deuteron beam. The conditions for the deposition at room temperature of stoichiometric PZT films were established.
Characterizat Ion of thin Pzt Films on Platinlm Films
Authors: Kugimiya Koichi , Ueda Ichiro , Iizima Kenji 
Published: March 2011

AbstractAnomalous layers 20-40nm thick were found at the interfaces of lead zirconate-titanate films and Pt electrode films. Detailed study has shown evidence that absorption of PbO by Pt during sputtering resulted in a Pb deficiency in the PZT films and the formation of PbTi3O7 phase. The anomaly was also partly due to island formation at the initial PZT film deposition which allowed PbO to react with Pt films. The Pb controlled PZT films 50nm thick exhibited excellent ferroelectric properties comparable to thicker ones.
Electrical Characterization of Sol-Gel Derived PZT Films
Authors: Teowee G. , Boulton J.M. , Lee S.C. , Uhlmann D.R. 
Published: March 2011

AbstractSol-gel derived PZT films were successfully prepared from precursor solutions based on lead acetate and Zr/Ti alkoxides. A pyrochlore phase was observed in films fired at low temperatures, while single-phase perovskite films were obtained at temperatures above 725C. The dielectric constant increased to above 1000 when there was a higher proportion of perovskite than pyrochlore. The films were essentially fatigue-free up to 108 cycles and exhibited a low aging rate of 5.7% / decade-sec.
Transmission Electron Microscopy Study of Mod Plzt and Pnzt Thin Films
Authors: Chang Jhing–Fang , Kwok Chi Kong , Desu Seshu B. 
Published: March 2011

AbstractBoth La and Nd–doped PZT, i.e., PLZT and PNZT, ferroelectric thin films were prepared by the metalorganic deposition (MOD) process. The precursor solutions used were derived from lead acetate, lanthanum acetylacetonate, neodymium acetate, zirconium n–propoxide, and titanium iso–propoxide. The dopant concentration of the films analyzed by electron microprobe indicated a one–to–one correspondence between film composition and the composition of the precursor from which the film was made. In this study, the effects of Nd and La dopants in PZT films on Curie temperature was determined by in–situ hot–stage TEM and compared with those of bulk materials. Lattice parameter and phase transformation were determined by both X–ray and electron diffraction. Our observations were: (1) Curie temperature decreases with increasing dopant concentration for both thin foils and bulk ceramics, (2) for a given dopant concentration, Curie temperature and crystal tetragonality of PNZT thin foils is lower than those of PLZT samples, (3) Curie temperature of thin foils was found to be less than those of the corresponding bulk materials, and (4) ferroelectric domains is easily observed in both PLZT and PNZT TEM specimens prepared by the spin–coating method.
Photovoltaic Effect in Thin Ferroelectric Films
Authors: Brody Philip S. , Rod B. J. , Cook L. P. , Schenck P. K. 
Published: March 2011

AbstractPolarization-dependent photovoltaic currents are observed in continuously illuminated ferroelectric thin films under conditions of polarization reversal. Following reversal, an initial current rapidly decays to an essentially steady current, which then decays slowly with the current decreasing in proportion to the logarithm of elapsed time. These polarization-dependent currents are attributed to the action of internal fields on photocarriers where the fields result from the incomplete screening of the polarization field.
SrTiO3 and (Ba,Sr)TiO3 Thin Films Preparation by Ion Beam Sputtering and Their Dielectric Properties
Authors: Yamamichi Shintaro , Sakuma Toshiyuki , Hase Takashi , Miyasaka Yoichi 
Published: March 2011

AbstractSrTiO3 and (Ba,Sr)TiO3 thin films have been prepared by ion beam sputtering on Pd coated sapphire substrates. Film compositions were almost the same as target compositions when powder targets were used. Capacitance-voltage characteristics depended on Sr/Ti ratio of the SrTiO3 films. Only small changes of capacitance value were observed in the range from -3V to 3V when the Sr/Ti ratio was 1.0. Compared with rf-magnetron sputtered film, ion beam sputtered SrTiO3 film indicated lower leakage current density in 50nm thickness. In (Bax,Sr1-x)TiO3 thin films, dielectric constant changed with Ba content (x) and showed a maximum at x=0.5. It also changed with the firing temperature of target powder. The highest value was obtained by using the target powder fired at 900°C. A 100nm thick (Ba0.5,Sr0.5)TiO3 thin film indicated a dielectric constant value of 320.
Electron Microscopic Study of Domains in Relaxor Ferroelectrics
Authors: de Graef Marc , Speck J.S. , Clarke D.R. , Dimos D. 
Published: March 2011

AbstractThe ferroelectric and antiferroelectric displacements in perovskite-based ceramics give rise to a wide range of domain structures. This paper reports on transmission electron microscopy observations as a function of temperature of such structures in PLZT and PLSnZT. In the PLZT system superposition of the diffraction patterns from modulated domains of low symmetry give rise to patterns with an apparent high symmetry. The ½(hkl)-type reflections become more intense with decreasing temperature and split into diffuse rods at high temperature. In the PLSnZT system a hierarchy of domain structures is observed with length scales ranging from unit cell dimensions to the full grain size. A temperature dependent long-period modulation along the < 110 > directions is observed.
Influence of Grain-Growth Inhibiting Dopants on the Electrophysical Properties of Rhombohedral Pyroelectric Lead Zirconate-Titanate Ceramics
Authors: Hahn Jean-Paul , Kostorz Gernot 
Published: March 2011

AbstractThe aim of this work was to develop a ceramic material exhibiting a large pyroelectric coefficient p = -dP/dT (P = polarization, T = temperature) and a low dielectric constant ∈ in order to obtain a high figure of merit F = p/∈pCp for applications in infrared temperature sensing (p denotes the sintered density of the ceramic, cp the specific heat). The influence of the dopants is paramount, and it was only possible to investigate a few promising ones. Best results were obtained for PZT 60/40 (Zr:Ti=60:40) doped with 2 mol% MnO2. The effects of various dopants and some aging results for PZT 60/40 with MnO2 are presented.
Investigation of Structure Development in Mod Pb(ZrxTi1-x)O3 Films by an Optical Method
Authors: Peng Chien H. , Desu Seshu B. 
Published: March 2011

AbstractFor i roving the metalorganic decomposition (MOD) process, such that perovskite Pb(ZrxTi1-x)O3 thin films can be fabricated at low temperatures, understanding of structure development is required. Here we report a nondestructive optical method for investigating the structure development in MOD PZT films. Using this method we have identified the temperatures at which the formation of both pyrochlore and perovskite was completed as a function of Zr/Ti ratio. Also for PZT solid solutions, we have identified the temperatures at which the initial presence of both pyrochlore and perovskite was observed. These temperatures compare very well with those obtained from the X-ray diffraction studies. In contrast to X-ray methods, the proposed technique can also be effectively utilized for studying the pyrochlore formation from the amorphous phase. Furthermore, it was also shown that the optical method can be used for characterizing the phase transformation kinetics in PZT films.
The Role of the Lead Zirconate Titanate (PZT)-Pt Interface in the Anomalous Phase Transformation Kinetics in Sputtered Pzt Thin Film Capacitors at Sub-2000 Å Thicknesses
Authors: Chikarmane Vinay , Kim Jiyoung , Sudhama C. , Lee Jack , Tasch Al , Novak Steve 
Published: March 2011

AbstractThe Pt-Lead Zirconate Titanate (PZT) thin film interface plays a key role in determining the electrical properties and phase transformation kinetics of Pt-PZT-Pt thin film capacitor structures. The results of the electrical and material properties of PZT (65/35) films that vary in thickness between 500 Å to 4000 Å deposited by DC-magnetron sputtering under identical deposition conditions, and subjected to the same post-deposition thermal processing conditions shows that the Pt-PZT interface dominates thin film properties at low thicknesses (≦ 2000 Å). The charge storage density (Qc') and maximum polarization (Pmax) shows an anomalous variation with thickness, showing an initial increase followed by a drastic decrease as the film thickness is scaled down to 500Å. Significant interdiffusion at the PZT film-Pt electrode retards the pyrochlore-to-perovskite phase transformation nucleation and growth rate in PZT films of thickness 2000Å and lower. Gate polarity dependence of the time-tobreakdown and the degradation field is observed for all PZT film thicknesses (including 4000Å). This indicates that the ferroelectric film-electrode interface has an important role to play in determining the electrical reliability properties even in the 4000Å thick PZT film, although Qc' and Pmax are not adversely affected at these thicknesses.
Preparation and Characterization of PbTiO3 and PbZrO3 Films from Oxide Multilayers
Authors: Li Chen C. , Desu Seshu B. 
Published: March 2011

AbstractPbTiO3 and PbZrO3 thin films were successfully fabricated from oxide multilayers by employing ion-assisted deposition process (IAD). Excellent control of the film thickness and composition were achieved by using the multilayer deposition technique. A (001)-oriented phase was found in the PbTiO3 films at 550°C with 300 and 600eV Ar+ ion bombardment. Very fine equiaxial grain size of 0.2μm was seen in the IAD deposited PbTiO3 films, which is independent of the Ar+ ion beam energy. The optical properties of the PbTiO3 films were studied for different energies of Ar+ ion beam and for various post-deposition annealing temperatures. PbTiO3 films with packing density of near unity (≅0.99) were obtained at temperatures as low as 600°C.