bluuebunny/crossref_metadata_2025_split huggingface dataset:
Field Effect Transistor Structure Based on Strain Induced Polarization Charges
Authors: Smith D.L. , Collins R.T. , Kuech T.F. , Mailhiot C. 
Published: March 2011

AbstractWe suggest a new field effect transistor based on strain-induced polarization charges. The structure utilizes the pseudomorphic growth of a strained barrier layer on a substrate oriented in a polar direction such as [111] or [211]. Polarization charges in the barrier layer are generated by the piezoelectric effect. A two-dimensional (2-D) electron gas, whose density can be modulated by an external bias, forms at the hetero-interface and it screens the polarization charge. Zero bias densities of several 1011 e/cm2 and threshold voltages of 0.5 V can be achieved. Both normally-on and normally-off structures are possible.
Morphology of Diamond Films Grown by DC Plasma Jet CVD
Authors: Kurihara Kazuaki , Sasaki Ken-Ichi , Kawarada Motonobu , Koshino Nagaaki 
Published: March 2011

ABSTRACTIt is well known that diamond films synthesized from the gas phase have well defined crystal habits which are affected strongly by synthesis conditions. Though there have been many studies of the morphologies of diamond films synthesized by microwave plasma CVD [1,2,3], there have been relatively few reports on the morphologies of these films grown using new high growth rate techniques such as DC plasma jet CVD [4]. Morphology control is very important to keep flat surface, when producing thick diamond films by high growth rate techniques. In this paper we report our investigation of the morphology and growth of diamond films synthesized by DC plasma jet CVD.
Deposition and Characterization of Carbon Films Produced by Nitrogen/Argon Mixture RF Sputtering
Authors: Tomg C. J. , Yeh T. , Sivertsen J. M. , Judy J. H. 
Published: March 2011

ABSTRACTThin carbon films were prepared by RF diode sputtering of a graphite target in a mixed nitrogen/argon plasma. A series of carbon films were deposited as a function of nitrogen partial pressure. We have observed a systematic variation of the properties of the carbon films with an increase of the nitrogen partial pressure. AES, XPS and energy gap studies showed that nitrogen will enhance the diamond sp3 bonding. Consistent with this the optical energy gap of our C:N films shows an increase from 1.1 eV to 1.4 eV using, respectively, 25 to 100 % nitrogen plasma. The mechanical properties also are shown to be enhanced for certain applications.
Predicted Infrared Spectrum and X-Ray Diffraction Patterns for Diamond Polyiypes
Authors: Phelps Andrew W. , Howard William , White William B. , Spear Karl E. , Huang D. 
Published: March 2011

ABSTRACTThe concept of diamond polytypism was examined and extended beyond the previous work to gain more analytical tools with which to understand and characterize these materials. This paper reports the band positions predicted for the expected infrared active modes of several diamond polytypes and the calculated diffraction patterns for the 21R and 15R polytypes. The infrared active modes were predicted on the basis of a generalized Brlllouin zone similar to that developed for silicon carbide polytypes. The diffraction patterns for the 21R and 15R polytypes were calculated in a manner similar to that used previously for the hexagonal polytypes. These results complete the suite of basic diffraction patterns for diamond polytypes.
A Study of the Electronic Structure Near Individual Dislocations in Diamond by Energy-Loss Spectroscopy
Authors: Bruley J. , Batson P. E. 
Published: March 2011

ABSTRACTSpatially resolved electron energy-loss spectra recorded from very small volumes of diamond containing individual dislocations show extra intensity within the band-gap just below the 1s to bulk conduction band threshold energy, when compared to spectra recorded from neighboring defect free regions. This is interpreted as direct evidence for the presence of vacant defect states associated with the dislocation structure. The contribution of the π* states from the surface layers to this region of the spectra is completely removed by calculating the difference between the spectra recorded on and off the defect. A comparison is drawn between the measured near edge structure and calculations of local density of states reported in the literature.
Intra- and Intergranular Fracture of Diamond Thin Films
Authors: Hoff H. A. , Morrish A. A. , Carrington W. A. , Butler J. E. , Rath B. B. 
Published: March 2011

ABSTRACTDiamond thin films have been synthesized at low pressures by chemical vapor deposition (CVD) and, recently, at ambient atmosphere with an oxygen-acetylene welding torch. By the application of appropriate thermal or mechanical stresses to the substrate, the diamond films can be delaminated. The delaminated films which are only a few microns thick have been fractured by manual bending. Scanning electron microscopy (SEM) examination of fractured CVD diamond films shows the presence of primarily intragranular fracture attesting to the inherent strength of the films. Using transmission electron microscopy (TEM), twinning and stacking faults are seen within the crystallites of the films along the fracture surfaces. By combining SEM and TEM examination, the relative degree of intragranular fracture found in films synthesized by both CVD and oxygen-acetylene torch has been investigated. Possible mechanisms for the intragranular fracture and the relative strength of such films are discussed.
Metallization of Semiconducting Diamond: Mo, Mo/Au and Mo/Ni/Au
Authors: Moazed K. L. , Zeidler J. R. , Taylor M. J. 
Published: March 2011

ABSTRACTA processing technology has been developed to make ohmic contacts to naturally doped semiconducting diamond. The approach follows, as far as possible, conventional photolithographic techniques for metallization of semiconductors currently in use in the microelectronics industry.
Carbon - silicon heterojunction diodes formed by CH4/ Ar rf plasma thin film deposition on Si substrates
Authors: Amaratunga G. A. J. , Milne W. I. , Putnis A. , Chan K. K. , Clay K. J. , Welland M. E. 
Published: March 2011

ABSTRACTThin C films deposited from a CH4/Ar plasma on Si substrates kept at 20C are shown to be semiconducting. The semiconducting properties are associated with the poly-crystalline diamond grains present within the films. Diode type I-V characteristics observed from AVC/Si verticle structures are explained by the action of a C-Si heterojunction. A band gap of 2eV, a resistivity of 106Ω.cm and an electrical breakdown strength of 5.106 V/cm are estimated for the C.
Liquid Phase Homoepitaxial Growth of 4H-SiC Crystals and Fabrication Techniques of Bluish-Purple Light-Emitting Diodes
Authors: Ueda Y. , Nakata T. , Koga K. , Matsushita Y. , Fujikawa Y. , Uetani T. , Yamaguchi T. , Niina T. 
Published: March 2011

ABSTRACT4H-SiC single crystals have been fabricated on the seeds of 6H-type crystals by the vacuum-sublimation (modified Lely) method at a temperature of 2400 °C and under a pressure of 2–60 mbar in an argon atmosphere. Liquid phase epitaxy was attempted by using a dipping method with a 4H-SiC off-orientation substrate whose {0001} C-face varied toward the <1120> direction by 5 degrees. The polytype of the grown crystals was found to be the 4H-type through measurements of Raman scattering and photoluminescence. P-n junction diodes were epitaxially obtained on 4H-SiC substrates. Aluminum and nitrogen were doped as acceptors and donors, respectively. The LED emitted bluish-purple light with a high brightness of 2.2 mcd at a forward current of 20 mA. Other characteristics were as follows : 420–425 nm peak wavelength, 90 % color purity, and a light output of 4 μW.
Status of β-SiC, Diamond and C-BN Semiconductors; Comparison of a Si Power Fet to a Hypothetical Diamond Fet
Authors: Koba Richard , Russell William 
Published: March 2011

ABSTRACTMonocrystalline β-SiC, diamond and cubic boron nitride (c-BN) are the three ultimate semiconductors. These materials show great promise as active semiconductors for power electronics because of their wide bandgap, the existence of substitutional dopants, their high dielectric strength, their low dielectric constant, and their high thermal conductivity. To illustrate their superiority, a conventional Si.power FET is compared to a theoretical diamond FET. By assuming the diamond FET can operate hotter and at a higher voltage, it is calculated that the diamond FET should deliver up to 35 times more power-to-load than the Si FET.
Infrared Study of Amorphous Crystalline Phase Transition in an Annealed Amorphous Hydrogenated Silicon Carbon Alloy Film
Authors: Basa D. K. , Smith F. W. 
Published: March 2011

ABSTRACTAn amorphous hydrogenated silicon carbon alloy film (a Si1 x Cx :H with x = 0.29) was prepared by glow discharge decomposition of a silane and ethylene gas mixture. A careful and detailed investigation of the infrared absorption was undertaken in the range 400 to 4000 cm1 for both the as deposited (T =250°C) and annealed (up to 1200°C) film. This study demonstrates clearly that there is a structural change from amorphous to microcrystalline at T =8000C and then to crystalline phase at T a=1200° C.
Native Defects, Diffusion, Self-Compensation, and Boron Doping in Cubic Silicon Carbide
Authors: Wang C. , Bemholc J. , Davis R. F. 
Published: March 2011

ABSTRACTWe report the results of a comprehensive theoretical investigation of the effects of stoichiometry and boron doping on the properties of cubic SiC. Supercell calculations using ab initio pseudopotentials show that the lowest energy defect in Si-rich n-type and intrinsic SiC is the electrically inactive Sic antisite, while VC++ is the lowest energy defect in p-type SiC. The electrons released by the carbon vacancies compensate acceptor dopants and lead to strong self-compensation effects when doping occurs during the growth of crystal. In C-rich SiC the dominant defect for all Fermi level positions is the electrically inactive CSi antisite. In stoichiometric and Si-rich cubic SiC, the BC site is energetically preferred, while BC and BSi have similar incorporation energies in C-rich material. In heavily doped p-type SiC the diffusion of BC proceeds by the dissociative (Frank-Turnbull) mechanism.
Deep-Level Dominated Electrical Characteristics of Au Contacts on β-SiC
Authors: Das K. , Kong H. S. , Petit J. B. , Bumgarner J. W. , Matus L. G. , Davis R. F. 
Published: March 2011

ABSTRACTCurrent-voltage characteristics of Au contacts formed on β-SiC films grown heteroepitaxially on both nominally (100) oriented and off-axis (100) silicon substrates have been investigated. Logarithmic plots of the I-V characteristics in the forward direction indicate space charge limited current conduction through the active volume of the diodes. The β-SiC films grown on nominally (100) oriented substrates show the presence of two deep levels located approximately between 0.26 eV and 0.38 eV below the conduction band edge. In some films on nominal (100) substrates, the I-V characteristics are also influenced by additional traps which are exponentially distributed in energy with a maximum occurring at the conduction band edge. In contrast, the films deposited on off-axis substrates have only one deep level located at approximately 0.49 eV for the 2° off (100) substrates and 0.57 eV for the 4° off (100) substrates. Previous microstructural analysis revealed that the nature and density of defects in the β-SiC heteroepitaxial films on both nominal and off-axis (100) silicon are similar except that the films on nominal (100) substrates have a high density of antiphase domain boundaries. Therefore, the presence of the shallower deep-level states observed in the β-SiC films grown on nominal (100) substrates is speculated to be due to the electrical activity of antiphase domain boundaries.
A New Deep Acceptor in Epitaxial Cubic SiC
Authors: Freitas J. A. , Bishop S. G. 
Published: March 2011

ABSTRACTThe temperature and excitation intensity dependence of photoluminescence (PL) spectra have been studied in thin films of SiC grown by chemical vapor deposition on Si (100) substrates. The low power PL spectra from all samples exhibited a donor-acceptor pair PL band which involves a previously undetected deep acceptor whose binding energy is approximately 470 meV. This deep acceptor is found in every sample studied independent of growth reactor, suggesting the possibility that this background acceptor is at least partially responsible for the high compensation observed in Hall effect studies of undoped films of cubic SiC.
Electronic Structure of Wide Bandgap Semiconductor Interfaces: Cubic SiC/AIN, SiC/BP, C/BN
Authors: Lambrecht W. R. L. , Segall B. 
Published: March 2011

ABSTRACTThe linear muffin-tin orbital supercell band-structure method is used to calculate the interface energy of formation, band offsets and local densities of states at the latticematched (110) heterojunctions between (cubic SiC)/(cubic AIN), (cubic SiC)/(cubic BP) and (diamond C)/(cubic BN). The lowest energy bonding configuration for SiC/AIN is found to be Si to N and C to Al bonding while for SiC/BP, Si is found to bind to B and C to P. The causes for these preferred bonding configurations are explained in terms of electrostatic effects. The band offsets are found to be of type II for SiC/BP and SiC/BN and of type I for SiC/AIN.
Growth and Physical Properties of rf-Magnetron Sputtered InN Semiconducting Films
Authors: Bryden W. A. , Morgan J. S. , Kistenmacher T. J. , Dayan D. , Fainchtein R. , Poehler T. O. 
Published: March 2011

ABSTRACTIndium nitride thin films have been deposited using reactive rf-magnetron sputtering and characterized by their electrical, structural and morphological properties. Films have been prepared on fused quartz and (0001) sapphire. Films deposited on sapphire at temperatures from 50–300°C are typified by a slowly increasing mobility and a transition from mixtures of epitaxial and textured grains to complete epitaxy. Comparisons of films deposited on quartz and sapphire (with two different surface preparations) indicates that electrical mobility is enhanced by the epitaxial nature of the material deposited on sapphire and that a higher quality surface finish results in superior films. Somewhat above 300°C the morphology of the epitaxial films changes from continuous to granular, with a concomitant loss in electrical connectivity. This manifests itself as a sharp rise in the resistivity of the film and hence a sharp decline in the mobility. The carrier concentration shows a general decline as the substrate temperature is increased, indicating that the mechanism of mobility degradation is probably not due to thermally induced nitrogen vacancy formation but more likely to unintentional oxygen doping. This is in accord with the surface oxidation observed in the films using Auger electron spectroscopy.
Substrate and Temperature Dependent Morphology of rf-Sputtered Indium Nitride Films
Authors: Kistenmacher T. J. , Dayan D. , Fainchtein R. , Bryden W. A. , Morgan J. S. , Poehler T. O. 
Published: March 2011

ABSTRACTThe morphology of rf-sputtered films of the wide bandgap semiconductor InN on a variety of substrates over a range of temperatures have been studied by X-ray diffraction (XRD) and scanning tunneling microscopy (STM). For films deposited on fused quartz and the (111) face of silicon, there is a transition from an off-normal inclination to a fully textured (0001) film with increasing substrate temperature. In contrast, films deposited on the (0001) face of sapphire are textured or heteroepitaxial depending on the substrate temperature. For the heteroepitaxial domains, the rotation of the reciprocal lattice of InN by 30° to that of the sapphire substrate was established by X-ray precession photography. Finally, STM has proven to be a practicable method for non-destructively determining the substrate and temperature dependence of the grain size and surface roughness of these textured and heteroepitaxial films.
Electron Microscopy of InN Films
Authors: Morgan J. S. , Kistenmacher T. J. , Bryden W. A. , Poehler T. O. 
Published: March 2011

ABSTRACTThis paper describes growth morphology and structure of rfmagnetron sputtered thin films of InN, studied by plan-view transmission electron microscopy (TEM) and by scanning electron microscopy (SEM). Films deposited on TEM grids, (0001) sapphire, (111) silicon and amorphous quartz were prepared for TEM by mechanical abrasion of the substrate followed by sputter etching. At low deposition temperatures (<400°C), films consisted of small, basal-oriented, columnar grains. Above 500°C, growth consisted of larger, faceted, basal-oriented, mesa-island grains. Observations of growth morphology and defect structure are correlated with structural, compositional and electrical properties.
MOCVD of Wide Bandgap III-V Semiconductors by using Novel Precursors
Authors: Ho Kwok-L. , Jensen Klavs F. , Hanson Scott A. , Evans John F. , Boyd David C. , Gladfelter Wayne L. 
Published: March 2011

ABSTRACTThin films of aluminum nitride have been grown by metalorganic chemical vapor deposition (MOCVD) from diethylaluminum azide. Growth rates of AIN on Si(111) were monitored in-situ with laser interferometry. The growth rate was linear in the partial pressure of the reactant at high temperatures and sublinear at low temperatures. A simple surface reaction mechanism consistent with these observations has been proposed. Surface reaction kinetics and mechanism were further investigated by steady-state kinetic mass spectrometry. Parameters in the growth rate expression were determined by a nonlinear regression of growth rate data. A typical sample of AIN on B-plane sapphire showed a bandgap of about 5.2eV which was increased to 5.9eV upon annealing in nitrogen at atmosphere pressure.
Room Temperature Excitonic Absorption in Small Cds Crystallites
Authors: Rai D.K. , Kumar Binod 
Published: March 2011

AbstractThe absorption characteristics of commercial CdS-containing yellow glass which shows constant transmitted intensity over a range of incident CW laser intensity have been studied at room temperature. Although the thick specimen (t>0.6 mm) shows only a broad step-like feature near λ>460 nm, a thin (t-0.09 mm) specimen shows two absorption features which can be interpreted as the first two quantum-confined exciton absorption features corresponding to a crystallite size of -45 Å. The absorption spectrum of a sample (t∼O.6 mm) heated for 15 min. at 700°C shows two new absorption features at 450 nm and 380 nm, which correspond to a much smaller crystallite size of -25 Å. This reduction in size is not inconsistent with estimates made from a well-known model for crystallite growth. Some consequences of these changes in the absorption features on the optical nonlinearities of the glass will be discussed.
Hydrogen Passivation of Doped and Undoped Microcrystalline Silicon
Authors: Stutzmann M. , Herrero C.P. , Ingels M. , Breitschwerdt A. 
Published: March 2011

AbstractThe effect of hydrogen plasma treatment on the properties of undoped and doped microcrystalline silicon are investigated by Raman and infrared spectroscopy, conductivity measurements, hydrogen effusion, and subgap absorption. It is found that hydrogen causes a passivation of dopant atoms similar to that seen in crystalline silicon. However, the efficiency of the dopant passivation appears to be smaller in μc-Si, and the vibrational spectra of dopants and hydrogen show distinct broadening due to local disorder. It is suggested that intergrain regions may efficiently getter atomic hydrogen introduced from the plasma and also provide the origin for a weakly bound hydrogen phase observed in the effusion experiments.
Control of Chemical Reactions for Growth of Crystalline Si at Low Substrate Temperature
Authors: Shimizu Isamu , Hanna Jun-Ichi , Shirai Hajime 
Published: March 2011

AbstractA systematic study has been made on the formation of Si-network of amorphous(a-), microcrystalline(μc-) and epitaxial (epi)-Si prepared by Plasma-Enhaced (PE-) CVD under control of flow of atomic hydrogen. The control of the Si-network structures requires a deliberate selection of the precursor, i.e., SiHn (n≤53) and SiFnHm (n+m≤53), as well as an intentional acceleration of the chemical reactions for the propagation of Si-network in the vicinity of the growing surface by impinging of atomic hydrogen. A plausible interpretation was given to the growing mechanism of c-Si at low temperature.
Enhanced Nonlinear Optical Response of Coated Nanoparticles
Authors: Kalyaniwalla N. , Haus J.W. , Birnboim M.H. , Inguva R. , Ma W.P. 
Published: March 2011

AbstractWe study coated, nanometer-size, ellipsoidal particles that have a semiconductor or polymer core surrounded by a metal coating. We predict that composite materials containing these particles will have much larger enhancement of the nonlinear optical response than had previously been found by using semiconductor colloid suspensions or semiconductor - doped glasses. The enhancement is due to the surface plasmon resonance from the metal dielectric constant that increases the local field in the core material. The frequency of the resonance and the enhancement depend upon the particle shape and the coating thickness, as well as on the specific materials.Also, we predict intrinsic optical bistability in these new materials and show that the threshold intensity for optical bistability can be greatly reduced by using the coated particles. We predict a switching intensity of silver coated GaAs particles below 100W/cm2
Power Density Effects in the Physical and Chemical Properties of Sputiered Diamond-Like Carbon thin Films
Authors: Cho N.-H. , Krishnan K.M. , Veirs D.K. , Rubin M.D. , Hopper C.B. , Bhushan B. , Bogy D.B. 
Published: March 2011

AbstractThin films of diamond-like amorphous carbon were prepared by dc magnetron sputtering. A systematic variation in the physical properties of the films (mass density and electrical resistivity) was found as a function of sputtering power density. Chemical bonding and microstructure of the carbon thin films were investigated using electron energy loss spectroscopy (EELS) and Raman spectroscopy. Films grown at a lower power density were found to have more sp3 -bonded atomic sites and larger graphite microcrystals than films produced at higher sputtering power densities.
Composition Determination of Microcrystalline Two-Phase Silicon Rich Oxides
Authors: Bouldin D.H. , Lam C.H. , Rose K. 
Published: March 2011

AbstractHRTEM measurements of silicon rich oxides (SRO) show silicon microcrystals in an oxide matrix [1]. Simple, reliable characterization of this two phase material has been a problem. Ellipsometric measurement of the refractive index is a convenient method for characterizing SRO films. Film composition can be related to the refractive index by Bruggeman's effective medium approximation. In this paper we demonstrate correlation of film compositions obtained by this technique with those obtained by Auger electron spectroscopy (AES)and Rutherford back scattering (RBS). We further demonstrate regimes of LPCVD growth where simple correlation of film composition with [N2 0]/[SiH4] gas ratios is not reliable.
Selective Growth of Si Crystals over Amorphous Substrates Seeded by Solid-State Agglomeration of Patterned Si
Authors: Yamagata K. , Yonehara T. 
Published: March 2011

AbstractSelective growth of Si crystals over amorphous substrates, seeded by agglomerated single domained Si crystals is demonstrated. In this method, Si crystal seeds are periodically placed and selectively overgrown until impingement upon adjacent crystals, resulting in a matrix of large Si islands with controlled grain boundary locations. Si seeds are formed over amorphous SiO2 by the solid-state agglomeration phenomenon, and grown selectively up to 100 μm by CVD selective epitaxial growth technique. The grown crystals are classified in three crystalline forms of single crystals, primary twins, and multiple twins. However, most are single crystals with a specific orientation of (110) normal to the substrate surface.