bluuebunny/crossref_metadata_2025_split huggingface dataset:
Epitaxial Explosive Crystallization of Amorphous Silicon Layers Buried in a Silicon (100) and (111) Matrix
Authors: Stolk P. A. , Polman A. , Sinke W. C. 
Published: March 2011

Abstract420 nm thick amorphous Si layers buried in a Si (100) or Si (111) matrix, produced by 350 keV Si-implantation, were irradiated using a pulsed ruby laser. Time-resolved reflectivity measurements show that melting can be initiated buried in the samples at the crystalline-amorphous interface. Melting is immediately followed by explosive crystallization of the buried amorphous layer, which is started from the crystalline top layer. The velocity of this self-sustained crystallization process is determined to be 15.0 ± 0.5 m/s for Si (100) and 14.0 ± 0.5 m/s for Si (111). RBS and cross-section TEM reveal that epitaxially grown crystalline Si, containing a high density of twin defects, is formed in both the Si (100) and the Si (111) sample.
Defects Produced by High Energy Oxygen Ions Implanted in Silicon
Authors: Grob A. , Grob J. J. , Perio A. , Thevenin P. , Siffert P. 
Published: March 2011

AbstractRutherford backscattering/channeling analysis was used to study the damage creation processes occuring during 1 MeV O+ implantation in silicon. The target temperature was varied from RT to 500°C using beam heating. The corresponding damage profiles and dechanneling behaviour were studied. Several implantations were performed at 77K for comparison. Transmission electron microscopy observations were connected to the dechanneling measurements in order to determine the dominant kind of defect in each case.For 77K implants, the defects are mainly interstitials distributed according the energy deposition in elastic collisions, extending up to the surface. At 500°C, the defects are imperfect dislocations confined in a narrow band around the mean range of oxygen ions. We demonstrate that dechanneling in samples implanted at intermediate temperatures results from a mixing of point defects and distorsion centers. The relative importance of the two kind of defects is followed as a function of implantation temperature.
Partially Ionized Beam Deposition of Thin Films
Authors: Lu T.-M. 
Published: March 2011

AbstractIt has been shown recently that using less than a few percent of self-ions, i.e., ions derived from the deposition material itself, (partially ionized beam (PIB) deposition), one can dramatically modify thin film properties. In this paper we discuss phenomena such as surface cleaning, enhanced surface ordering, and ion-induced surface damage associated with PIB-surface interactions. PIB metal deposition has been emphasized.
Compensation :in GaAs/GaAlAs Heterostructures by Ion Implantation Comparison of Oxygen and Boron
Authors: Descouts B. , Tasselli J. 
Published: March 2011

AbstractIon implantation has been used to form an insulating layer in GaAs/GaAlAs heterostructures for bipolar transistor applications with the aim of reducing the base-collector capacitance. Two ions have been compared : boron and oxygen. In both cases magnesium has been implanted to contact the base layer and rapid thermal annealing has been used to activate this dopant. We show that the base-collector capacitance can be lowered by a factor of ∼,2 with oxygen, but high oxygen doses (≥, 1014 ions/cm2 ) are necessary to obtain reproducible results. The capacitance is lowere!6 by 2 a factor of ∼4 with optimized boron dose. With high boron doses (≥ 1013 /cm2 ) we have decreased the capacitance by a factor of 16 but the defects created during the implantation affect the properties of the emitter and base layer.
Implant Damage in AlGaAs Based Superlattices and Alloys at 77K
Authors: Dobisz E. A. , Dietrich H. , McCormick A. W. , Harbison J. P. 
Published: March 2011

AbstractPreviously, it was shown that superlattices implanted with Si at 77K, exhibited more extensive damage and uniform compositional mixing upon subsequent annealing than samples implanted at room temperature.[l,2] The current work focuses on the damage in samples implanted with Si at 77K. The study shows that for a given dose, the amount of damage depends upon the layer thickness and the composition. Specimens of bulk GaAs, Al 3Ga. 7As, 7.5 nm GaAs -10 nm Al. 3Ga. 7As superlattice (SL1), 5.5 nm GaAs −3.5 nm AlAs superlattice (SL2), and 8.0 nm GaAs −8.0 nm AlAs superlat-tice (SL3) were implanted at 77K with 100 KeV Si, with doses ranging from 3 × 1013 cm−2 to 1 × 1015 cm−2. The samples were examined by ion channelling and cross sectional transmission electron microscopy (TEM). At 77K and a dose of 1 × 1014 cm−2, the GaAs and SLi showed an amorphous layer, while no damage peak was observed in SL2. The 77K amorphization thresholds of the Al 3Ga. 7As alloy, SL2, and SL3 were 2.5 × 1014 cm−2, 4 × 1014 cm−2, and 1 × 1015 cm−2 respectively. The sharpness of the amorphization threshold varied with the material.
SIMS Determination of MG+ and AS+ Range Profiles in Photoresist and Polyimide Implant Masks.
Authors: Dugger D. L. , Stern M. B. , Rubico T. M. 
Published: March 2011

AbstractThe distribution of Mg+ (a p-type dopant for GaAs) and As+ (an p-type dopant for Si) implanted into both photoresist (PR) and polyimide (PI) have been determined experimentally. Range data of Mg ions at 200 keV and 300 keV and As ions at 150 keV have been measured by Secondary Ion Mass Spectroscopy (SIMS). SIMS values for the projected range Rp and the standard deviation ARp were compared to range profile data calculated using the Projected Range Algorithm (PRAL) of Biersack [1] as well as the standard LSS theory [2]. While the values for Rp calculated from the PRAL model generally agreed within 10% of the SIMS values, the calculations underestimated Rp for PR but were in good agreement for PI. The LSS calculations underestimated Rp in both materials.
Study of Thermodynamic Phase Stability of Intermetallic Thin Films of Pt2Ga, Ptga and PtGa2 on Gallium Arsenide
Authors: Kim Young K. , Shuh David K. , Williams R. Stanley , Sadwick Larry P. , Wang Kang L. 
Published: March 2011

ABSTRACTEpitaxial thin films of three different Pt-Ga intermetallic compounds have been grown on GaAs by molecular beam epitaxy (MBE). The resultant films have been annealed at various temperatures and then examined using X-ray two-theta diffraction. Both PtGa2 and PtGa thin films are chemically stable on GaAs under 1 atmosphere of N2 up to 450°C and 600°C, respectively. Thin films of Pt2Ga react with GaAs at temperatures as low as 200°C to form phases with higher Ga concentration.
The Effect of Annealing on the Structure of Epitaxial CaF2 Films on Si(100)
Authors: Phillips Julia M. , Palmer J. E. , Hecker N. E. , Thompson C. V. 
Published: March 2011

ABSTRACTWe have studied the effect of different annealing conditions on the crystallinity and morphology of 1000Å epitaxial CaF2 films on Si(100). The crystallinity of the films is improved by the anneals, with the highest anneal temperatures giving the greatest improvement. The results are consistent with the model previously proposed to explain the success of rapid thermal annealing in improving thicker epitaxial CaF2 films.
Effects of Growth Temperature on MOCVD-Grown GaAs-ON-Si
Authors: Nozaki S. , Noto N. , Okada M. , Egawa T. , Soga T. , Jimbo T. , Umeno M. 
Published: March 2011

ABSTRACTEffects of growth temperature on crystallinity and surface morphology of MOCVD-grown GaAs-on-Si were studied. The FWHM of the (400) x-ray peak in the rocking curve of GaAs-on-Si reduces from 340 to 230 arcs with increasing growth temperature from 650 to 700°C, but further increase of growth temperature does not significantly decrease the FWHM. The surface morphology of GaAs-on-Si grown at higher temperature is scaly and rough. Lower growth temperature is desirable to obtain GaAs-on-Si with good surface morphology. In order to eliminate the trade-off between crystallinity and surface morphology, the three-step growth process is proposed.
Evaluation of Anti-Phase-Boundaries in GaAs/Si Heterostructures by Transmission Electron Microscopy
Authors: Ueda O. , Soga T. , Jimbo T. , Umeno M. 
Published: March 2011

ABSTRACTThe nature and behavior of anti-phase-boundaries in GaAs/Si heterostructures using GaP, GaP/GaAsP and GaAsP/GaAs strained layer superlattices as intermediate buffer layers, have been investigated by transmission electron microscopy. It has been found that anti-phasedomains are very complicated three dimensional polygons consisting of several sub-boundaries in different orientations. Self-annihilation of anti-phase-domains during crystal growth of GaAs on (001)just or (001)2°off Si substrates is directly observed for the first time through planview and cross-sectional observations. Based on these findings, a mechanism of annihilation of these domains is proposed.
Correlation Between Crystallinity and Schottky Diode Characteristics of GaAs Grown on Siby MOCVD
Authors: Egawa T. , Nozaki S. , Noto N. , Soga T. , Jimbo T. , Umeno M. 
Published: March 2011

ABSTRACTWe have studied the crystallinity and Schottky diode characteristics of GaAs/Si grown by MOCVD. In comparison with two-step growth and GaP/strained layer superlattice techniques, the crystallinity and the Schottky diode characteristics are superior for the GaAs/Si with Al0.5Ga0.5P as an intermediate layer. The GaAs/Si grown with the Al0.5Ga0.5 intermediate layer shows mirror—like surface morphology and an X-ray FMHM of 188 arcs. The ideality factor of the Schottky diode fabricated on the GaAs/Si grown with the Al0.5Ga0.5P intermediate layer is 1.06, but its forward current-voltage characteristic shows a significant leakage current at small forward bias. It is also found that the composition of Al affects strongly the crystallinity and the Schottky characteristics of GaAs/Si.
Interfacial Microstructures in InxGa1-xAs/GaAs Strained Layer Structures
Authors: Yao J. Y. , Andersson T. G. , Dunlop G. L. 
Published: March 2011

ABSTRACTThe interfacial microstructures of lattice strained InxGal-xAs/GaAs multiple layer structures, that were grown by molecular beam epitaxy (MBE) on GaAs (100) substrates, have been investigated and characterised by transmission electron microscopy (TEM). A g3ii weak beam imaging technique has been used to study structural imperfections at the heterointerfaces. The morphology of rough heterointerfaces, which resulted from the growth of the InxGal-xAs layers (strained layer) either in a two dimensional (2D) or in a three dimensional (3D) growth mode via island formation, was imaged using this technique. A transition from 2D to 3D growth was found to occur at a certain critical layer thickness which decreased with increasing indium fraction. In thicker layers, dislocation complexes, which may have been caused bythe formation of islands, were also observed. These complexes were primarily composed ofstacking faults bounded by partial dislocations.
A Novel Method for Study of Roughness at Buried Interfaces by Plan View Tem: Si/SiO2
Authors: Gibson J. M. , Lanzerotti M. Y. 
Published: March 2011

ABSTRACTInterfacial roughness can be measured at buried interfaces using plan view transmission electron diffraction. The method relies on surface termination Bragg reflections and is applied to the Si/SiO2 system. In contrast to other methods, this does not require stripping of the SiO2 overlayer or projection assumptions. We find that thermal oxide interfaces are significantly flatter than previously supposed.The Si/SiO2 interface has been extensively examined by a wide variety of techniques. A subset of these studies have focussed on the interfacial roughness and it has been shown that increased step density reduces electron mobility.[1, 2 ] Although supporting the correlation of mobility with step density, the data presented here shows thermally oxidized Si/SiO2 interfaces to be significantly flatter than previously assumed.
Position-Sensitive Atom Probe and Stem Analysis of the Microchemistry of GaInAs/Inp Quantum Wells
Authors: Liddle J. Alex , Long N.J. , Norman A.G. , Cerezo A. , Grovenor C.R.M. 
Published: March 2011

ABSTRACTThe recently developed techniques of pulsed laser atom probe microanalysis (PLAP) and position sensitive atom probe (POSAP) have been applied to the study of quantum well interfaces in samples that have also been well characterised by the more conventional techniques of TEM and STEM. These techniques have the potential for providing chemical information with a spatial resolution of better than 2nm, but the atom probe has the ability to independently resolve morphological and microchemical features of interfaces in three dimensions.This paper presents results taken from GaInAs/lnP MOCVD-grown samples, comparing information on well composition, and on the chemical abruptness and morphological roughness of interfaces using complementary analysis techniques. We have concentrated on obtaining reliable quantitative data on the phosphorous content of the GaInAs wells and on the gallium and arsenic contents of the InP barrier layers.
Correlation Between Defect Production and Excitonic Emission in the Irradiated ZnSe-ZnS Strained-Layer Superlattices
Authors: Sekoguchi Maki , Taguchi Tsunemasa 
Published: March 2011

ABSTRACTThe effects of thermal heat-treatment, N+ -ion, Ar+ -ion, γ-ray and electron-beam irradiations have been studied on MOCVD-grown ZnSe-ZnS strained-layer superlattices (SLSs) by means of low-temperature photoluminescence and X-ray diffraction measurements. As-grown SLS structure seems to be stable against the heat-treatment compared to ZnSe thin film, but after the defects are introduced in the SLS by irradiation, additional fluctuation at the interface between the ZnSe well and the ZnS barrier layers takes place. However, no significant intermixing and the changes of strain can be detected in the irradiated SLS.
Deep Level Transient Spectroscopy of Defects Induced by the Combination of CF4Reactive Ion Etching and Oxidation in Metal-Oxide-Silicon Capacitors.
Authors: Vuillaume Dominique , Gambino Jeff P. 
Published: March 2011

ABSTRACTMetal-Oxide-silicon (MOS) capacitors have been fabricated on CFbreactive ion etched silicon (n and p types) in order to study the defects at the Si-Si02interface and in the bulk of the substrate, produced by the combination of reactive ion etching (RIE) and oxidation. Bulk defects and fast interface states are analysed by Deep Level Transient Spectroscopy (DLTS) and the slow interface states in the oxide layer near the interface are probed by Tunnel-DLTS. A density of fast interface states in the range 1010-1011cm−2eV−1is observed for capacitors (both n and p types) fabricated with either dry or wet oxidations, and is probably due to disrupted or strained bonds at the Si-SiO2interface. The observation of bulk defects in the wet-RIE oxide samples but not in the dry-RIE oxide samples may be related to the shorter oxidation time for wet oxides (31mn) compared to dry oxides(190mn) and explained by a greater annealing of RIE induced defects during the dry oxidation. The bulk traps are identified to be related to carbon contamination, in SiC form, introduced during RIE. Finally, an increase of the slow interface states density is observed for the n-type dry oxide samples.
Interaction of Oxygen with Native Chemical Defects in CuInSe2 Thin Films
Authors: Noufi Rommel , Cahen David 
Published: March 2011

ABSTRACTWe formulate a consistent defect chemical model of the effect of air/02 anneals on CuInSe2 polycrystalline thin films. The model centers on O-induced neutralization of (near) surface donor states in CuInSe2 grains. The simplest identification of these states is with ionized Se vacancies, due to coordinatively unsaturated In on grain surfaces and boundaries.
A Model for Interdiffusion at Metal Semiconductor Interfaces: Conditions for Spiking
Authors: Hellman Olof C. , Herbots Nicole , Eng David C. 
Published: March 2011

ABSTRACTWe have derived a dynamical model for interdiffusion at aluminum-silicon interfaces which can explain the great variety of rates of interdiffusion observed for this system. The variables addressed by the model include the degree of covalent bonding which occurs at the chemical interface and the local atomic structure of that interface. Local solid solubility data and maximum rates of dissolution are derived analytically, and good agreement is observed between the model and both thermodynamic data for the bulk aluminum-silicon system and kinetic data for reaction rates at differently prepared interfaces. The influence of dopants and structural defects on the predictions of the model is in accord with experimental observations. The model points to some critical conditions for the preparation of thermally stable aluminum-silicon interfaces, which are potentially applicable to other metal-semiconductor systems.
MoirÉ Pattern Studies of Thin Layers Deposited on (001)Si Substrates: Cases of Tisi2 and GaAs.
Authors: Rocher A. , Wallart X. , Charasse M.N. 
Published: March 2011

ABSTRACTMoiré pattern images have been used to investigate the crystalline quality of thin films deposited on (100)Si substrates. Observations performed on TiSi2 show a three-dimensional growth process and two different epitaxial modes. In the case of GaAs epilayers, it is shown that the residual strains are not uniformly distributed in the layer. Residual strain and threading dislocations are related to imperfections of the misfit dislocation network.
Spin Relaxation Spectroscopy of the D-Center in Hydrogenated Amorphous Silicon
Authors: Zafar Sufi , Schiff E. A. 
Published: March 2011

ABSTRACTMeasurements of the dependence of the D-center electron paramagnetic resonance absorption signal upon the incident microwave power are reported in undoped hydrogenated amorphous silicon (a-Si:H) for specimens prepared at differing deposition temperatures and also as the state of a given specimen was varied by illumination and subsequent annealing. These measurements are sensitive to electron spin relaxation processes of the D-center. Substantial variation in spin-relaxation behavior was found, corresponding to approximately one order of magnitude in the spin relaxation rate; no significant variations in absorption lineshape were observed. A model for these spin relaxation observations invoking two differing local microstructures near the D-center is proposed. The model indicates that illumination increases the density of defects in one microstructure but can irreversibly diminish the density in a second.
Thermal Equilibrium Defects in Hydrogenated Amorphous Silicon Based Alloy Films
Authors: Xu Xixiang , Morimoto Akiharu , Kumeda Minoru , Shimizu Tatsuo 
Published: March 2011

ABSTRACTBoth the temperature dependence at elevated temperature and the increase after fast cooling from elevated temperature of the density of dangling bonds are measured by ESR for undoped hydrogenated amorphous silicon–based alloy films, a–Si:H, a–Si1−xCx:H, a–Si1−xNx:H and a–Si1−xOx:H. Both a–Si:H and a–Si1−xCx:H clearly show the increase in the density of dangling bonds at elevated temperature, while the increase is less prominent for a–Si1−xNx:H and a–Si1−xOx:H. The observed results for both a–Si:H and a–Si1−xCx:H are fairly well reproduced by the model recently proposed by Smith et al. The results of CPM measurements combined with those of ESR measurements suggest that the density of charged dangling bonds present in undoped a–Si:H also increases after fast cooling from elevated temperature.
Distribution of Gap States in Highly Photosensitive a-SiC:H
Authors: Akita S. , Nakayama Y. , Yamano M. , Kawamura T. 
Published: March 2011

ABSTRACTThe effect of carbon incorporation into a-Si:H has been investigated in terms of gap states. The shallow and deep states are measured by a combination of two methods of the time-of-flight and the depletion discharge transient spectroscopy. The results show that the carbon incorporation of 10Z into a-Si:H leads to a slight increase in the conduction-band tail states and an extention of the deep states distribution. However, the increase in the shallow states affects little change in the electron transport properties. The origin of the deep states is also discussed.
Low Temperature Characteristics of Hydrogenated Amorphous Silicon Field Effect Transistors
Authors: Bae Byung-Seong , Cho Deok-Ho , Lee Jae-Hee , Lee Choochon , Jang Jin 
Published: March 2011

ABSTRACTWe investigated the temperature dependent characteristics of hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFT's) at temperatures down to 20 K. With decreasing temperature, the threshold voltage increased, the field effect mobility and the on-current decreased. The measured on-currents versus inverse temperature above 80 K are represented as the sum of two exponentially varied currents. It is concluded that on-current is nearest-neighbour hopping between 120 K and 80 K. Below this temperature, the temperature dependence of on-current is explained by variable range hopping and below about 30 K on-current becomes nearly independent of temperature. At very low temperature hopping probability may be governed not by temperature but by temperature independent tunneling, depending on the overlap of the wave function. The explanation of threshold voltage increase at low temperature is given.
From the Understanding of the Reaction Mechanism Towards Optimizing the Deposition Rate and Optoelectronic Properties of a-Si:H
Authors: Veprek S. , Heintze M. , Bayer R. , Jurčik-Rajman N. 
Published: March 2011

ABSTRACTWe present new results of kinetic studies of the deposition of high quality a-Si:H which strongly support the reaction mechanism suggested in our earlier papers: 1. SiH4 → SiH2; 2. SiH2 + SiS4 → Si2H6 (SiH2 + Si2H6 → Si3H6); 3. Si2H6 → 2a-Si:H (Si3H8 → 3a-Si:H). The “SiH3 mechanism”, as promoted by several workers, is in contradiction with these experimental facts.The di- and trisilane, which have a much higher reactive sticking coefficient than monosilane, play the role of reactive intermediates which facilitate the heterogeneous decomposition of silicon carrying species at the surface of the growing film. The values of the reactive sticking coefficient of Si2H6 and Si3H8 depend on the surface coverage by chemisorbed hydrogen; they increase with decreasing surface coverage. Under the conditions of the growth of high quality a-Si:H films the reactive sticking coefficient of disilane amounts to 10−4 to 10−2 which is in a good agreement with recent data of other authors.The rate determining step of the growth of high quality a-Si:H films is the desorption of hydrogen from the surface of the growing film. This can be strongly enhanced by ion bombardment at impact energy of <100 eV. In this way, homogeneous, good quality films were deposited at rates up to 1800 Angströms/min, and there is a well justified hope that this rate can be further increased.
Comments on Electron and Hole Transport in the Band Tail States of Amorphous Silicon at Low Temperatures
Authors: Silver M. , Spear W. E. 
Published: March 2011

ABSTRACTRecent experimental results on the low temperature drift mobility in amorphous silicon are examined on the basis of the approach to hopping transport developed by Silver and Bässler. It is shown on general grounds that the main features of the experimental results cannot be explained by a purely exponential tail state distribution, but are consistent with the distribution used by Spear and Cloude (1988) in model calculations.
Optical Bias Enhanced Transient Photoconductivity in a-Si:H
Authors: Chen Xing , Tai Chen-Yu 
Published: March 2011

ABSTRACTOptical bias enhancement in transient photocurrent, by a factor of more than 10, is observed in a-Si:H films. The transient photocurrent is found to decay exponentially shortly after the light pulse is turned off. The exponential decay constant of the transient current is found to be proportional to (optical bias level)−0.38 at room temperature. A theory based on the multiple trapping model is developed to explain the experimental result. This effect is applied to study the density of state of the sample as well as the process of charge recombination.