bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deep Level Transient Spectroscopy Study of Thin Film Diamond
Authors: Srikanth K. , Ashok S. , Zhu W. , Badzian A. , Messier R. 
Published: March 2011

ABSTRACTWe have demonstrated the applicability of DLTS to semiconducting diamond thin films. This paper includes details on the capacitance-voltage measurements, the DLTS spectrum and the DLTS spectra as a function of bias. Our study was done with an aluminum Schottky contact on polycrystalline diamond film. We found a strong temperature dependence of the Schottky diode capacitance with a reduction of effective dopant concentration from 4 × 1014 cm−3 at 300K to 2 × 1014 cm−3 at 200K. The DLTS signal had a good signal to noise ratio, characteristic line-shape and clear peaks. The trap concentration was 8 × 1013 cm−3 (at 400/s rate window) with an activation energy of 0.31 eV and a capture cross section of 1.15 × 10−18 cm−2. The spectra showed a bias dependence of peak height and position.
N-Type Doping and Diffusion of Impurities in Diamond
Authors: Kajihara S. A. , Antonelli A. , Bernholc J. 
Published: March 2011

ABSTRACTFirst-principles calculations were used to study Li, Na, and P as prospective shallow donors in diamond. As expected, P prefers the substitutional site while Li and Na are interstitial donors. All three impurities were found to be shallow. However, their solubilities are very low, which makes them unsuitable for incorporation into diamond via in-diffusion. Instead, kinetic trapping during growth or ion implantation must be used. Interstitial impurities are particularly appropriate for ion implantation, since there is no need to replace host atoms. Considering the stability of the impurity at the dopant site, substitutional P is expected to diffuse by the vacancy mechanism and to have a high activation energy by analogy to self-diffusion. For Li and Na, the activation energies for interstitial channel diffusion are 0.85 and 1.6 eV, respectively. Li is thus a fast diffuser even at room temperature, while Na would remain stable up to moderate temperatures.
Electrical Behavior of Diffused Impurities in Diamond Single Crystals
Authors: Narducci Dario , Cuomo Jerome J. 
Published: March 2011

ABSTRACTThe dependence of the electrical properties on the evolving doping profile during diffusion processes was studied, as well as the role of the vacancies in determining the electrical properties of diamonds. To this aim, B was deposited on diamond single-crystal by physical vapor deposition. The element was then thermally diffused into diamond at 800°C under helium atmosphere. The deposited layer was finally removed and subsequent annealing cycles were carried out. The diffusion profiles were tracked by Nuclear Analysis Techniques. For comparison, the same element was implanted in diamonds at 70 K and at room temperature. Electrical contacts of different metals were deposited on diamond and the current-voltage and the capacity-voltage characteristics were measured. A comparative analysis of the electrical behavior of implanted and diffused samples was carried out, which elucidated the electronic activity of point defects in diamond.
Low Temperature Metal Organic Chemical Vapor Deposition (LTMOCVD) of Electronic Materials
Authors: Kaloyeros Alain E. , Toscano Paul J. , Rizk Richard B. , Tulchinsky Victor , Greene Alex 
Published: March 2011

ABSTRACTHigh quality amorphous and crystalline silicon carbide thin films were produced by low temperature metal-organic chemical vapor deposition (LTMOCVD) using the organometallic precursor tetraethynylsilane, Si(C2 H)4. LTMOCVD, which was developed by the present investigators, uses single source precursors containing all the elemental constituents desired in the target material already directly bonded. This approach eliminates the inherent limitations of conventional MOCVD where separate precursors are used for each of the individual components of the desired compound. LTMOCVD thus combines the ability to deposit films at low temperatures, which is characteristic of physical deposition techniques, with the ability to provide complete coverage at steps or irregularities on the semiconductor surface, which is characteristic of chemical deposition techniques. In addition, the precursors employed are non-toxic, non-hazardous and easy to handle. Consequently, LTMOCVD can produce compound semiconductors on thermally fragile or chemically sensitive substrates. The SiC films were grown in a hot-wall CVD reactor at a reactor pressure of 10−6-10−3 torr and substrate temperature in the range 300–700°C. Characterization studies were performed using electron diffraction (ED), Auger electron spectroscopy (AES), Rutherford backscattering (RBS), x-ray photoelectron spectroscopy (XPS), and electron energy loss spectroscopy (EELS). The results of these studies showed that the films were uniform, continuous, adherent and highly pure– contaminant levels were below the detection limits of the techniques employed.
Doped Amorphous SiC, Mixed Carbide and Oxycarbide Thin Films by a Liquid Route
Authors: Chu C-J , Liimatta E. , Mackenzie J. D. 
Published: March 2011

ABSTRACTA new family of disordered materials called amorphous covalent ceramics (ACC) has been obtained by pyrolysis of metal-organic polymers. The transformation from polycarbosilane to amorphous and microcrystalline SiC has been studied. New a-SiC:H thin films have also been prepared by the polymer solution. Electrical and optical properties of this new a-SiC have studied. Amorphous binary carbide and oxycarbide have also been prepared by crosslinking polycarbosilane and metal alkoxides. The p-n control of this new a-SiC:H has been achieved, which also lead to the possible device applications.
Growth of Epitaxical SiC Layers onto on and off Axis 6H SiC Substrates by Ion Beam Deposition
Authors: More K. L. , Withrow S. P. , Haynes T. E. , Zuhr R. A. 
Published: March 2011

ABSTRACTThin films of β SiC have been grown epitaxically onto on axis (0001) 6H α SiC substrates using ion beam deposition. The ion beam deposition technique involves the direct deposition of alternating layers of 13C+ and 30Si+. The carbon and silicon ions were obtained from an ion implanter by decelerating mass analyzed ion beams to 40 eV. The SiC substrate was held at ∼973 K. Thin films of α-SiC (a mixture of α- polytypes) were obtained following deposition onto off axis (∼2°) 6H α-SiC. High resolution electron microscopy and Rutherford backscattering techniques were used to determine the structure and crystalline perfection of the resulting layers.
Sem Observation of Growth and Defect Formation of Heteroepitaxially grown sic on (100) Silicon
Authors: Molnar B. , Shirey L. M. 
Published: March 2011

ABSTRACTSingle crystal, cubic SiC films used in this study were grown by a two step CVD process on (100) oriented silicon substrates. The two surfaces of such grown SiC films are different. The SiC surface at the Si/SiC interface is more conductive than the SiC/air surface. This Si/SiC surface appears smooth under optical microscopy, but Scanning Electron Microscopy (SEM) reveals characteristic “growth features” on it. Each growth feature protrudes from the smooth SiC surface, and most often it either fills or borders the rectangular shallow pyramids present on the (100) Si surfaces. Plasma etching of the SiC at the Si/SiC interface creates cavities with vertical boundaries. Some of the cavities have been traced to the original location of some growth features.
Cubic Boron Nitride Crystals Grown at High Pressure: PN Junction, Crystallographic Polarity and Some Properties
Authors: Mishima Osamu 
Published: March 2011

ABSTRACTStudies on the cubic boron nitride (cBN) crystals grown by the temperature difference method at high pressure are reviewed. The electron beam induced current measurement, the electrical measurement, and the optical measurement demonstrated that the cBN is a good potential candidate as a wide-gap semiconductor material. The Raman spectrum and the reflectance and transmittance spectra of the cBN were obtained. The crys-tallographic polarity of cBN crystals was directly determined from the Rutherford backscattering spectroscopy (RBS).The RBS experiment showed that the (111) surface which adjoins to the (100) surface at an obtuse angle so that the edge between the (111) and the (100) is parallel to the <110> direction of striations on the (100) face is a triply bonded nitrogen-terminating face. The result seems to disagree with that derived from other semiconductor compounds.
Boron Phosphide as a Refractory Semiconductor
Authors: Kumashiro Y. , Hirabayashi M. , Takagi S. 
Published: March 2011

ABSTRACTThe crystal growth, characterization and various characteristics such as electrical, thermal and semiconducting properties of boron phosphide (BP) single crystalline wafers made by chemical vapor deposition technique are summrized. It is demonstrated that Schottky diode using single crystal and thermoelectric device employing sintered polycrystal are promising application for electronic materials.
In-Situ Synthesis and Magnetically Stabilized Kyropoulos Growth of Undoped Indium Phosphide
Authors: Bachowski Stephen , Ahern Brian S. , Hilton Robert M. , Adamski Joseph A. 
Published: March 2011

AbstractThe Kyropoulos growth technique has been combined with in-situ synthesis to yield high purity undoped crystals of 300 to 700 gm charges of InP. Etched wafers show a uniform dislocation density across 70mm diameter in contrast with the "W" pattern created by LEC. Use of an axial magnetic field in Kyropoulos growth reduces the dislocation density by an order of magnitude, to 1 × 104cm-2. By combining Kyropoulos growth with in-situ synthesis of the indium phosphide, high mobility (4.6×104 at 77 C) undoped single crystals have been obtained.
Electrical Properties of Heavily Be-doped GaAs grown by Molecular Beam Epitaxy
Authors: Shibata H. , Makita Y. , Yamada A. , Ohnishi N. , Mori M. , Nakayama Y. , Beye A. C. , Mayer K. M. , Takahashi T. , Sugiyama Y. , Tacano M. , Ishituka K. , Matsumori T. 
Published: March 2011

AbstractElectrical properties of heavily Be-doped GaAs grown by molecular beam epitaxy were investigated systematically in a wide range of Be-concentration from 1× 1014 up to 2× 1020 cm-3 by using yan der Pauw technique. Probable carrier scattering mechanisms observed in this work are discussed by taking into account the radiative mechanisms of several new photoluminescence emissions previously observed in the band-edge-emission region of the samples. All samples were checked their electrical properties first at room-temperature. Five selected samples out of them were measured from 10° K up to room-temperature. Samples having the carrier concentration from 1014 to 1018 cm3 presented typical semiconductor-like conduction with finite carrier excitation energy. For samples having carrier concentration 7× 1016 cm -3, the conduction mechanism at high temperature region above 30β K was dominated by holes thermally excited into valence band. At low temperature region below 30° K . it was dominated by holes hopping from neutral to ionized acceptors with the assistance of phonons. Hole mobilities of samples having the carrier concentration from 1017 to 1018 cm-3 showed an anomalous behavior in the low temperature region, which suggests the presence of a new type of carrier scattering mechanism. A radiative center denoted by lg-gl observed in this concentration region will be a candidate scattering center to explain these electrical behaviors. Samples having the carrier concentration larger than 1019 cm-3 demonstrated typically metallic electric conduction not owing to thermally excited carriers, which means that an impurity band is formed but merged with valence band. The density of state of this combined valence band mixed with impurity band can be supposed to reflect carrier concentration dependence of the PL emission bands observed in this region, i.e. [g-g]α , [g-g]β and [g-g]γ .
Laser-Thermal Impurity Pumping of Shallow Donors in Ultrapure Germanium
Authors: Theiler T. , Keilmann F. , Haller E. E. 
Published: March 2011

AbstractExtremely narrow far-infrared lines [1] of OH-donors in ultrapure germanium are used to probe the fundamental dynamic processes of impurities. We examine the 1s-2p transition as a function of laser intensity, using photothermal ionization spectroscopy (PTIS) modified by Zeeman tuning with frequency-fixed lasers. We observe a change of the resonance line shape in the intensity region near 10-4 W/cm2. This effect can be quantitatively understood in a rate equation model which shows that at the critical intensity the ground state becomes depleted and the dependence of the recombination on the degree of ionization becomes important. Therefore the critical intensity depends also on compensation.
Identification of Surface-Related Electron Traps in Undoped GaAs by Deep Level Transient Spectroscopy
Authors: Shin Ki-Chul , Park In-Shik 
Published: March 2011

AbstractUsing undoped GaAs containing grain boundary, we performed annealing test to identify the processes occurring during heat treatment. We propose EL2 as a complex of double vacancy, AsGa and Asi. From the concentration change at grain boundary region we temporarily conclude that EL3 is a simple intrinsic defect.
Pressure Dependence of a Deep Excitonic Level in Silicon
Authors: Northrop G.A. , Wolford D.J. 
Published: March 2011

AbstractCertain optically active defects in silicon provide a unique opportunity to observe, in detail, the effect of hydrostatic pressure on a deep level. We present a photoluminescence (5 – 100K) study of one such defect, the I, radiation-damage center, under high hydrostatic pressures (1–50 kbar). While the energy variation of this level indicates the expected mutli-band nature typical of a deep level, a severe and continuous reduction in the observed luminescence intensity was also observed. Temperature dependence, time resolved photoluminescence, and photoluminescence excitation spectroscopy are employed to attempt to discern the mechanism involved.
Multiconfigurational Carbon-Group V Pair Defects in Silicon
Authors: Gürer E. , Benson B. W. 
Published: March 2011

AbstractIn addition to a new configuration of the previously reported multistable carbon-phosphorus pair, we report on two new multiconfìgurational defects in electron irradiated silicon doped, with arsenic and antimony. These defects are also identified as interstitial carbon-substitutional group V pairs, (). We identified two different types of metastability for . Type I is similar to the bistable carbon-carbon pair defect for which a bond switching mechanism has been reported [1]. Type II is similar to donor-acceptor pairs in silicon which show electrostatically driven metastability [2,3]. The three pairs have many similar features, but also show surprising donor related differences. In this paper we will discuss the general features of these defects.
Deep Levels in Superlattices
Authors: Dow John D. , Yuan Ren Shang , Shen Jun , Tsai Min-Hsiung 
Published: March 2011

AbstractThe physics of deep levels in semiconductors is reviewed, with emphasis on the fact that all substitutional impurities produce deep levels - some of which may not lie within the fundamental band gap. The character of a dopant changes when one of the deep levels moves into or out of the fundamental gap in response to a perturbation such as pressure or change of host composition. For example, Si on a Ga site in GaAs is a shallow donor, but becomes a deep trap for x>0.3 in AℓxGa1-xAs. Such shallow-deep transitions can be induced in superlattices by changing the period-widths and quantum confinement. A good rule of thumb for deep levels in superlattices is that the energy levels with respect to vacuum are relatively insensitive (on a >0.1 eV scale) to superlattice period-widths, but that the band edges of the superlattices are sensitive to changes of period. Hence the deep level positions relative to the band edges are sensitive to the period-widths, and shallow-deep transitions can be induced by band-gap engineering the superlattice periods.
Hydrogen Passivation Studies in Dislocated CZ and FZ Silicon
Authors: Dubé C. , Kalejs J. P. , Rajendran S. 
Published: March 2011

AbstractHydrogen passivation using a Kaufmann ion source at 400°C has been carried out on FZ and CZ silicon dislocated by four-point bending at high temperatures. The results differ from those reported for dislocations passivated in silicon sheet grown by the EFG technique. A model for hydrogen diffusion and trapping is presented to argue that the differences observed are not produced by hydrogen transport effects in the bulk.
The Formation of Silicon-Rich Silicides
Authors: Ronay Maria , Schad R.G. 
Published: March 2011

AbstractDiffusion studies of mono and bilaycrs of transition-metal films on silicon showed that the formation of η′ —Cu3Si lowers the formation temperature of subsequently forming ReSi2 by 400°C. This is due to the creation of a large amount of silicon self-interstitials accompanying the formation of the copper suicide, which lowers the activation energy for silicon diffusion. The generalization of this result - stating that the formation of all suicides, in which the volume density of silicon is much larger than in elementary silicon injects silicon self-intcrstitials into the silicon lattice - gives new insight into suicide formation, silicide-cnhanccd dopant diffusion and the self-diffusion of silicon itself6.
Diffusion and Interdiffusion in Multilayered Semiconductor Systems
Authors: Ourmazd A. , Kim Y. , Bode M. 
Published: March 2011

AbstractWe apply quantitative chemical mapping techniques to study thermal interdiffusion and ion-implantation induced intermixing at single heterointerfaces at the atomic level. Our results show thermal interdiffusion to be strongly depth dependent. This is related to the need for the presence of native point defects (interstitials and vacancies) to bring about interdiffusion. Since their initial concentration in the bulk is negligible, the point defects must be injected at the surface and transported to the interface for interdiffusion to occur. In the case of ion-implanted samples, we find the passage of a single energetic ion through a sample at 77 K causes significant intermixing, even when the sample receives no subsequent thermal treatment.
Diffusion of Ion Implanted Mg and Be in GaAs
Authors: Robinson H. G. , Deal M. D. , Stevenson D. A. 
Published: March 2011

AbstractAnnealed Mg implants into GaAs show three diffusion regions: 1) rapid uphill diffusion in the peak of the implant; 2) rapid concentration-independent diffusion in the tail; and 3) slow concentration-dependent diffusion in between. Implanted Be, in contrast, exhibits only concentration-dependent diffusion. Constant Fermi level experiments show that this diffusion is actually hole-dependent. Uphill diffusion can be induced in Be implants by co-implanting with a heavier element such as Ar. Paradoxically, this retards the concentration-dependent diffusion. This behavior can be explained with the Substitutional-Interstitial-Diffusion (SID) mechanism and an understanding of the defect chemistry after implantation. In the region of uphill diffusion, the dopants are seen to getter from areas of excess Ga interstitials toward areas of excess Ga vacancies. The magnitude of the Ga interstitial gradient with respect to the dopant concentration is shown to be critical for the uphill diffusion. The reduction in concentration-dependent diffusion with co-implants is thought to be caused by implant damage allowing dopant atoms to shift from interstitial to substitutional sites.
Defect Formation During Zn Diffusion into GaAs
Authors: Luysberg Martina , Jäger W. , Urban K. , Perret M. , Stolwijk N.A. , Mehrer H. 
Published: March 2011

AbstractThe microstructure induced by the Zn diffusion at 1170 K into doped and undoped semi-insulating GaAs single crystals was characterized for various diffusion times t < 1740 min by analytical electron microscopy. The results were compared with Zn concentration profiles obtained by spreading resistance measurements (SRM) on the same samples. At the diffusion front the formation of prismatic interstitial dislocation loops, dislocation networks, and of cavities partly filled with Ga was observed. Closer to the surface facetted voids and, for the undoped samples, vacancy-type dislocation loops formed. The near surface region of highest Zn-concentration showed a high density of Zn-rich precipitates. A model is presented which accounts .for these observations. It is based on fast interstitial Zn diffusion and the kick-out mechanism for interstitial-substituional exchange.
The Metastability of the EL2 and DX Defects in GaAs and 3-5 Alloys
Authors: von Bardeleben H.J. , Bourgoin J.C. 
Published: March 2011

AbstractThe metastability of the EL2 and DX defects in GaAs and Ga1-x AlxAs alloys is discussed in the context of recent hydrostatic pressure and photo-EPR results. A unified model is presented based on the metastable trapping of carriers in excited effective-mass (EM) states derived from secondary conduction band (CB) minima. The metastability is attributed to small lattice relaxation effects.
Characteristics of Doping and Diffusion of Heavily Doped N and P type InP and InGaAs Epitaxial Layers grown by Metal Organic Chemical Vapor Deposition
Authors: Pinzone C.J. , Ha N. T. , Gerrard N. D. , Dupuis R. D. , Luftman H. S. 
Published: March 2011

AbstractElectronic and photonic device applications of the InGaAs/InP materials system often require the growth of epitaxial material doped to or near the solubility limit of the impurity in the host material. These requirements present an extreme challenge for the crystal grower. To produce devices with abrupt dopant profiles, preserve the junction during subsequent growth, and retain a high degree of crystalline perfection, it is necessary to understand the limits of dopant incorporation and the behavior of the impurity in the material.In this study, N-type doping above 1019 cm-3 has been achieved in InP and InGaAs using Sn as a dopant P-type Zn doping at these levels has also been achieved in these materials but p type activation above ~3 × 1018 cm-3 in InP has not been seen. All materials were grown by the metalorganic chemical vapor deposition (MOCVD) crystal growth technique. Effective diffusion coefficients have been measured for Zn and Sn in both materials from analysis of secondary ion mass spectra (SIMS) of specially grown and annealed samples.
Defects in MBE-grown Silicon Epilayers Studied with Variable-Energy Positrons
Authors: Simpson P.J. , Schultz P.J. , Mitchell I.V. , Jackman T.E. , Aers G.C. 
Published: March 2011

AbstractFew non-destructive techniques are available which provide information regarding defect type, concentration and depth distribution in semiconductors. The variable-energy positron beam technique has recently demonstrated a sensitivity to near surface defects and impurities at low defect concentrations. In the present study, intrinsic silicon (100) epilayers of ~3000 Å thickness grown by MBE at different temperatures were examined by this method for evidence of changing defect concentration and type.
Enhancement of Oxygen Precipitation in Quenched Czochralski Silicon Crystals
Authors: Hara A. , Fukuda T. , Hirai I. , Ohsawa A. 
Published: March 2011

AbstractWe studied oxygen precipitation in quenched Czochralski silicon crystals. The larger the cooling rate and the higher the quenching temperature, the more oxygen precipitated. The defects enhancing oxygen precipitation are eliminated by annealing above 900°C. The defects are formed and removed repeatedly by quenching and slow cooling. We think that the aggregation of vacancies is related to those defects.