bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrogen Dynamics and Tee Distribution of H Sites in Undoped a-Si:H and a-Ge:H
Authors: Shinar R. , Wu X.-L. , Mitra S. , Shinar J. 
Published: March 2011

ABSTRACTSecondary ion mass spectrometry and IR studies of long-range hydrogen motion in undoped a-Si:H and a-Ge:H of varying H content and microstructure are reviewed and discussed. In particular, their relation to the multiple trapping (MT) model, the role of microvoids, the significance of the Meyer-Neldel relation (MNR), and the nature of H sites is addressed. It is suggested that while the MT mechanism may be significant in a-Si:H of low H content Cfj, it is largely marginal in films where CH ≥ 10 at.% H and in a-Ge:H. Mono Si-H bonds on microvoid surfaces are apparently deep H trapping sites up to ∼ 400°C, but H is desorbed from such sites in a-Ge:H above 180°C. The MNR between the diffusional activation energy and prefactor is observed among the various a-Si:H and a-Ge:H, but its significance is questionable, and may be due to the MT mechanism only in low H content a-Si:H. The nature of the distribution of H sites is also discussed.
Deposition of Amorphous and Microcrystalline Si,C Alloy Thin Films by a Remote Plasma-Enhanced Chemical-Vapor Deposition Process
Authors: Wang C. , Lucovsky G. , Nemanich R. J. 
Published: March 2011

ABSTRACTWe have extended the remote PECVD process to the deposition of intrinsic and doped, amorphous and microcrystalline silicon, carbon alloy films, a-Si,C:H and μc-Si,C, respectively. The electrical and optical properties of a-Si,C:H deposited by remote PECVD are comparable to those of films deposited by the glow discharge or GD process. The degree of crystallinity in the μc-Si,C alloys, as determined from the relative intensities of crystalline and amorphous features in the Raman spectra, is lower than that of μc-Si films deposited under comparable deposition conditions. The Raman spectra indicate that the crystallites in the μc-Si,C alloys are Si, while the infrared measurements establish that the intervening amorphous component is an a-Si,C:H alloy.
Composition and Properties of PECVD Silicon Nitride Films Deposited from SiH4, N2, He Gases
Authors: Souk J. H. , Parsons G. N. , Batey J. 
Published: March 2011

ABSTRACTAmorphous silicon nitride films deposited from a gas mixture of SiH4 and N2 with a large flow of He have shown many interesting characteristics. The films show a wide variety of electrical, optical, and mechanical properties with varying amounts of SiH4 and N2. The effect of N2 flow rate on film composition in N2-SiH4 processes is quite different from that of NH3 flow in NH3-SiH4 processes. The films were characterized by measurements of (1) Si-H and N-H bond density and bonded hydrogen content, both from infrared absorption, (2) Si/N ratio, (3) refractive index, (4) film stress, and (5) wet chemical etch rate and (6) electrical properties including current-voltage (I-V) and capacitance-voltage (C-V). We find that adding helium to the PECVD process enhances the incorporation of nitrogen in the film and an optimized flow of SiH4 improves the electrical properties. Films with optimum electrical properties with minimum charge trapping are obtained with N/Si ratio close to 1.33. These films have a small amount of Si-H and N-H bonds, and a low etch rate (> 100 A/min) in aqueous HF solution. The properties of these low temperature (250°C) PECVD nitrides have many similarities with LPCVD nitrides. Compared with films deposited from SiH4, NH3 mixture, these films exhibit very low wet etch rates and much lower H contents, but greater hysteresis in C-V characteristics.
Hopping Conduction in a-Si:H Studied by Transient Photoconductivity with Optical Bias Illumination
Authors: Chen Xing , Jayamaha Upali , Tai Chen-Yu 
Published: March 2011

ABSTRACTCharge transport in a-Si:H films is studied by measuring the intensity and the rate of decay of the transient photocurrent with optical bias illumination. The optical bias enhancement of the transient photocurrent due to the probe beam decreases at first as the temperature is decreased, reaches a minimum at about 21OK, and then increases as the temperature is further decreased. This observation, together with the decay time measurements, indicates a change in the mechanism of charge propagation from conduction band transport at high temperature to hopping conduction in the low temperature. A theory of hopping conduction in tail states is developed to explain the experimental results. A quantitative comparison of the theoretical and experimental results is made to determine the localization length of the tail states.
Phase Equilibria in Hydrogen Binary Mixtures From 63 to 280 K and Pressures to 6000 Bars
Authors: Streett William B. , Heintz Andreas , Clancy Paulette , Chokappa Dhanraj 
Published: March 2011

ABSTRACTExperimental measurements have been carried out to determine the compositions of coexisting gas and liquid phases for binary mixtures of hydrogen with the following substances as the second component: nitrogen, carbon monoxide, argon, methane, ethylene, ethane and carbon dioxide. For most of these mixtures the entire region of gas-liquid equilibrium has been explored for the first time. This region is bounded in pressure-temperature space by the vapor-pressure curve of the heavy component, the gas-liquid critical line (where gas and liquid phases become identical) and the 3-phase region solid-liquid-gas. In all of the systems described here the latter two lines intersect to form a critical end point. The general qualitative features of these phase diagrams are described, and compared to those of helium mixtures studied earlier.
Melting Processes and Crystal Structure of Solid 4He Al High Densities
Authors: Besson J.M. , Le Toullec R. , Loubeyre P. , Pinceaux J.P. , Hansen J.P. 
Published: March 2011

ABSTRACTSolid-fluid equilibrium has been measured in 4He between 7 and 18GPa (220 - 400K). The melting line is fitted up to 280K, for an f.c.c. solid, using an exponential pair potential. Experimental evidence for a b.c.c. phase at high temperature is discussed and compared with two calculations on the relative stability of the two structures.
Vibrational Dephasing and Collision Induced Scattering in Molecular Liquids
Authors: Jonas Jiri 
Published: March 2011

ABSTRACTThe results of several Raman studies of vibrational dephasing in polyatomic molecular liquids at high pressure are reviewed. The density and temperature effects on vibrational dephasing of isotropic Raman bands for different vibrational models are reported for the following liquids: C(CH3)4; Si(CH3)4; Ge(CH3)4; ; Sn(CH3)4and isobutylene CH2; = C(CH3)2.The experimental data are used to test the current theoretical models of vibrational dephasing. Selected results of our high pressure experiments on collision induced scattering in polyatomic molecular liquids demonstrate well the essential role of high pressure in studying these phenomena.
Structure Transition of Metallic Glasses of Alloys Annealed at High Pressure for the Exploration of Superconducting Compounds
Authors: Shou-an HE , Wen-Kui Wang , Iwasaki Hiroshi , Syono Yasuhiko 
Published: March 2011

ABSTRACTIn this article, the formation of superconducting compounds through structure transition of metallic glasses at high pressure high temperature are emphasized, and investigations on structure transition of metallic glasses made of niobiun alloys and lanthanun alloys are summarized.
The Nature of the Critical Point Phase Transition in Metals
Authors: Hensel F. 
Published: March 2011

ABSTRACTThe paper presents recent experimental results of optical, electrical and thermophysical properties of fluid metals in the vicinity of the critical point. Special attention will be paid to the metal-nonmetal transition which occurs at reduced densities of a fluid metal and the plasma phase transitions which are connected with ionization phenomena and many particle interactions in the dense vapor. The interrelation between the gas-liquid critical point phase transition and these electronic transitions and their effect on the critical phenomena will be discussed.
Equation of State of Fluid NH3 from P-V-T and Ultrasound Measurements to 12 Kbar
Authors: Mills R. L. , Liebenberg D. H. , Le Sar R. , Pruzan PH. 
Published: March 2011

ABSTRACTA piston-cylinder apparatus was used to measure the pressure, volume, temperature, and ultrasonic velocity (P,V,T,u) of fluid NH3 from 195 to 320 K at pressures up to 12 kbar. Over 1200 sets of P-V-T-u and P-V-T data were fitted to a Tait-type equation of state (EOS) by non-linear least-squares minimization. With quadratic terms in T for the two fitted parameters, the rms deviation is ± 0.2% in V and ± 0.9% in u, which is comparable to the experimental error. The simple Tait EOS is useful over the entire fluid range between the vaporization and melting curves up to T exceeding room temperature. Measurements of u and calculations of the constant-pressure heat capacity Cp show regular behavior, differing noticeably from values given by a 44-parameter EOS recently published by NBS. It is concluded that incorporating u in the formulation of an EOS improves its self consistency markedly.
Direct Imaging of Ordering in Si-Ge Alloys, Ultrathin Superlattices, and Buried Ge Layers
Authors: Jesson D. E. , Pennycook S. J. , Baribeau J. -M. 
Published: March 2011

ABSTRACTWe review recent Z-contrast imaging studies of Si-Ge ultrathin superlattices, alloys, and buried Ge layers. It is found that whenever Si is deposited onto a Ge (2 × 1) surface, Ge is pumped into the growing Si layer, and this is accompanied by interfacial ordering. This is explained by a novel Ge atom pump mechanism which occurs during MBE growth. Codeposition and alloy growth results in long range (111) ordering as a consequence of lateral segregation during nonequilibrium growth.
Electron Microdiffraction Investigation of a GexSi1−x Buffer for Strain-Symmetrised Superlattice Structures
Authors: Pike W. T. , Kubiak R. A. A. , Parker E. H. C. , Whall T. E. 
Published: March 2011

ABSTRACTA candidate GeSi buffer layer structure suitable for strain-symmetrised GeSi/Si superlattice overgrowth is grown by molecular-beam epitaxy and its strain state characterised using microdiffraction in a dedicated scanning transmission electron microscope. The structure consists of five alloy layers of increasing Ge concentration grown on a Si (100) substrate, with all but the last annealed at high temperature. Analysis of higher order Laue zone deficit lines in the microdiffraction patterns acquired from each layer indicate that relaxation is complete in all the layers. Images of the structure in the transmission electron microscope show good crystallinity of the final layer with low concentrations of threading dislocations.
The Selective Epitaxy of Silicon at Low Temperatures
Authors: Lou Jen-Chung , Oldham William G. , Kawayoshi Harry , Ling Peiching 
Published: March 2011

ABSTRACTLow-temperature selective epitaxial growth (SEG) of silicon using a dichlorosilane-hydrogen mixture in an LPCVD hot-wall reactor has been discussed with respect to the wafer preparation and the deposition cycle. The surface morphology and the quality of epilayers are strongly affected by residual oxide islands at interface. A reduction of local growth rate near interfacial oxides is attributed to the dissolution of oxide at interface, and this reduction can lead to pits and textured features on the Si epitaxial surface. An ex-situ HF vapor or an HF dip with an in-situ small DCS 900°C prebake step can completely remove surface oxide prior to the deposition and achieve defect-free Si epilayers at the deposition temperatures of 850°C and 800°C. It is also found that fluorine atoms can play a major role in the removal of surface oxide.
Electrical and Optical Properties of Erbium in MBE Silicon and Si/Ge Alloys
Authors: Efeoglu H. , Evans J. H. , Langer J. M. , Peaker A. R. , Rowell N. L. , Noel J-P , Perovic D. D. , Jackman T. E. , Houghton D. C. 
Published: March 2011

ABSTRACTThis paper reports the incorporation of erbium into MBE Si and Si/Ge alloys with substrate temperatures of 500°C and 700°C. Using a solid source MBE system, concentrations of erbium between 1018 and 1022 cm−3 have been studied by photoluminescence, electrical measurements, SIMS and TEM. We find no shallow donors or acceptors attributable to erbium but we observe a high concentration of deep states with an activation energy of ∼360 meV. The photoluminescence output is of greatest magnitude when [Er] =2 × 1018 cm−3. Above this concentration the onset of erbium precipitates can just be observed using TEM and at even higher concentrations structured growths of erbium suicide are apparent. The effect on the optical activity of Si:Er that has subsequently been implanted with oxygen is also reported.
Wave Function Engineering of Linear and Non-Linear Optical Response in Si-Ge Quantum Well Structures and Superlattices
Authors: Jaros M. , Turton R. J. , Wong K. B. 
Published: March 2011

ABSTRACTWe show that the infinite Si-Ge superlattices predicted to exhibit strong optical transitions across the fundamental gap and between conduction subbands also give rise to significant optical nonlinearities. Efficient optical transitions can also be achieved in finite-length structures grown on Si or Ge substrates. However, the zone folding argument does not apply and the electronic structure strongly reflects the finite length of such systems.
Magneto-Transport Measurements on Si/Si1−xGex Resonant Tunneling Structures
Authors: Gennser Ulf , Kesan V. P , Syphers D. A. , Smith T. P. , Iyer S. S , Yang E. S. 
Published: March 2011

ABSTRACTWe have investigated magneto-transport properties of differently strained Si/ Si1−xGex resonant tunneling devices. The built-in strain was either put in the Si layers, by means of a thick., relaxed Si1−xGex buffer layer, or in the Si1−xGex layers, in which case all Si1−xGex layers were grown below the critical thickness, and a Si1−xGex spacer layer with graded Ge content was used. Magnetic fields parallel to the interface have been employed to probe the in-plane dispersion in the quantum well. This is used to study the effect of band-mixing in the two strain configurations. A field perpendicular to the interface resolves some Landau level splitting. Most strikingly, however, is the similarity in the spectra with the case when the magnetic field is applied parallel to the interfaces. This indicates broadening of the levels, possibly due to scattering, and the importance of 3-dimensional band structure effects.
Substrate Engineering with Fluoride Buffer Layers on Si
Authors: Taylor A. P. , Li W. , Xiao Q.-F. , Schowalter L. J. 
Published: March 2011

ABSTRACTHere, we report on our efforts to engineer Si substrates for growth of compound semiconductors through the use of suitable epitaxial buffer layers of CaF2, SrF2, and BaF2 using a recently installed dual growth chamber MBE system. We have also developed new graphite-heater K-cells which have demonstrated reliable, high temperature deposition of the fluorides with excellent uniformity across substrates up to 6 inches in diameter. Excellent epitaxial quality (Xmin<5.0%) and smooth surface morphologies have been achieved for epitaxial CaF2 and SrF2 grown directly on Si (111) and BaF2 grown directly on Si (001). The BaF2 is (111) oriented on the Si (001) substrates with one of the {110} planes of the BaF2 aligned with the (110) plane in the Si (001). PbS1−xSex of excellent epitaxial quality has recently been demonstrated on the BaF2 (111)/Si (001) films. Comparable epitaxial quality has been demonstrated for CaF2 grown on Si (001) substrates using a two step growth method. We also report on preliminary results on epitaxial mixed fluoride growth on Si (111) and Si (001) substrates.
The “Computer-Aided Epitaxy” Si:MBE-Control System
Authors: Kubiak R. A. , Newstead S. M. , Powell A. R. , Bowen D. K. , Barlow R. D. , Dowsett M. G. , Whall T. E. , Parker E. H. C. 
Published: March 2011

ABSTRACTA dedicated, grower-friendly MBE computer control system is described, and its performance in demonstrated in growth of high resolution doped SiGe structures.
Selective Growth of Heteroepitaxial GexSi1−x/Si Lateral Wells Using Pulsed Laser Induced Epitaxy
Authors: Chang Yih , Kramer J. , Chou S. Y. , Sigmon T. W. , Marshall A. F. 
Published: March 2011

ABSTRACTPatterned GexSi1−x/Si wells are fabricated for the first time by pulsed laser induced epitaxy technique, employing two different semiconductor processing steps to grow these structures selectively. Two different dimensions of Gt0.12 Si0.55 /Si wells are sucessfully formed, in which one is 3.5 μm wide and 1700Å deep while another is 6 μm wide and 1300Å deep. Transmission electron microscopy combined with energy-dispersive X-ray imaging reveals that the 2-D Ge redistribution profiles are well defined and no significant line or surface defects observed. The 2-D Ge well redistribution behavior, governed by heat and mass transport during laser processing, are also discussed.
The Effect of Line Geometry on Void Growth in Thin, Narrow Aluminum Lines
Authors: Børgesen P. , Lee J. K. , Korhonen M. A. , Li C.-Y. 
Published: March 2011

ABSTRACTThe stress induced growth of individual voids in passivated Al-lines at room temperature was monitored in-situ, without removing the passivation. The kinetics was strongly influenced by variations in line geometry, even over distances of many μm, indicating variations in the stress relaxation as well.
Numerical Analysis of the Ball Forming Process in Copper Ball Bonding
Authors: Hongyuan Fang , Yiyu Qian , Yihong Jiang 
Published: March 2011

ABSTRACTIn this paper, the forming process of copper wire ball in copper ball bonding has been studied by numerical analysis. By means of calculation of temperature field, speed field and displacement field for ultrafine copper wire under a miniarc, the regular pattern of copper wire ball formation has been clarified. In this paper, the calculating result of displacement field has also been tested and verified.
Automatic Determination of In-Depth Profiles of Recombination Lifetime in Epitaxial Si Layer with P+-N−-N+ Stripe Test Pattern Diodes
Authors: Usami Akira , Fujii Yoshimaro , Fujiwara Hideki , Sone Tomiyasu , Wada Takao 
Published: March 2011

ABSTRACTRecombination lifetime of a epitaxial layer (epilayer) is automatically measured by using the conductivity modulation technique. A lateral p+-n−-n+ diode test structure on the surface of the epilayer is formed to evaluate the minority carrier lifetime. Depth profiles of the recombination lifetime are obtained from current-voltage curves of a lateral p+-n−-n+ diode and a vertical n+-n−-n+ structure between the substrate and the top surface. We measure the lifetime in epilayers with and without a buffer-layer. In addition, photo-response of photodiodes with and without the buffer-layer is measured. Profiles of the recombination lifetime depend on the thickness of the epilayer but not on the thickness of the buffer-layer. Minority carrier lifetime in the epilayer, and the leakage current and the photo-response of photodiodes are improved by the buffer-layer formation between epilayer and substrate.
Characterization of Failure Mechanisms and Failure Rate of Oxide Wearout by Hot Electron Using D.C. and A.C. Substrate Electron Injection
Authors: Nishida Toshikazu , Thompson Scott E. , Kavalieros Jack T. 
Published: March 2011

ABSTRACTDetermination of the failure mechanisms and failure rate of oxide wearout by hot carrier injection in submicron metal-oxide-semiconductor field-effect-transistor (MOSFET) requires special test structures to isolate the oxide field dependence of oxide trap generation and charging. A bipolar-MOS transistor (BiMOS) structure is used which d.c. injects substrate electrons into the gate oxide of a MOS transistor by forward biasing the emitter-base n+/p junction of a vertical n+/p/n-inversion-layer bipolar junction transistor. The field and temperature dependences enable a separation of thermal and tunnel electron detrapping rates at low and high oxide field from the generation rate of new oxide traps at high fields. Pulsed a.c. substrate electron injection in a n+ sourced metal-oxide-semiconductor capacitor (SMOSC) structure is used to characterize the field dependence of oxide degradation in chlorinated oxides.
Basic Concepts in Electromigration
Authors: Sorbello Richard S. 
Published: March 2011

ABSTRACTA review of basic concepts in electromigration is presented and recent theoretical developments are discussed. The microscopic origin of the driving force for electromigration is elucidated and, as an example, the driving force exerted on an impurity near a grain boundary is calculated in a jellium model. A connection is made between the calculated electromigration driving force and 1/f-noise measurements. Results of the first computer simulations of electromigration at the microscopic level are presented. It is found that dynamical recoil effects can lead to a significant enhancement of electromigration for light interstitial impurities.
Electromigration Characteristics Under High Frequency Pulsed Current Stressing
Authors: Kwok Thomas , Kaufman R. , Davari B. 
Published: March 2011

ABSTRACTElectromigration characteristics of Al lines under pulsed current stressing at frequencies 50–200 MHz were measured. Lifetime was found to depend explicitly on both current on-time and current off period. Lifetime increases with t-off as t50 ∝ (t-off)2.2 and decreases with t-on as t50 ∝ (t-on)−0.7. The data indicate no threshold frequency for drastic change in lifetime. Lifetime was also found to increase with duty cycle as t50 ∝ r−2.7, which is a remarkable improvement over an average current density model.
Electromigration in Al/W and Al(Cu)/W Interconnect Structures
Authors: Hu C-K. , Ho P. S. , Small M. B. , Kelleher K. 
Published: March 2011

ABSTRACTThe electromigration drift velocity of Al in Al(3wt.% Si), Al(2wt.%Cu), and Al(2wt.%Cu,3wt.%Si) was measured in a temperature range 133 to 220 °C with current densities of 1.0 to 1.5×106A/cm2. In Al(3wt.% Si), a significant Al depletion at the cathode end and accumulation at the anode end of stripe were observed within a few hours at 1.5×106A/cm2 and 200°C. In addition, local hillocks and voids along the metal lines were observed. For Al(Cu,Si), the Al drift velocity was slowed down by Cu addition. The majority of hillocks started to grow at a distance about 6 μm away from the cathode end with current density of 1.5×106 A/cm2. The drift velocity of Al in Al(Cu,Si) was found to be a function of time starting with an initial low value and increasing to a an final steady-state value. The behavior was attributed to the migration of Cu and dissolution of Al2Cu precipitates. The activation energies of the depletion 3 Aμm of Al(2%,Cu, 3%Si) was determined to be 0.90±02 eV. The dissolution and growth of A12Cu in the tested samples of Ti/Al(2%Cu)/Ti/TiN were observed using the scanning electron microscope and an electron microprobe.