bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth and properties of epitaxial PbSe on Si(111) and Si(100) without buffer layer
Authors: Müller P. , Tiwari A.N. , Zogg H. 
Published: April 2011

Narrow gap IV-VI materials like PbS, PbSnSe and PbSnTe are used for infrared detector device fabrication [1,2]. Earlier an intermediate Ila-fluoride buffer layer, which consisted of a BaF2/CaF2-stack of about 2000 Å thickness, was used to get epitaxial high quality layers on silicon substrates. This buffer is now reduced to a much thinner layer of only about 20 Å thick CaF2, regardless the large lattice mismatch between layer and substrate [3,4,5]. The question therefore arises if high quality IV-VI layers can be grown on Si-substrates without any buffer layer as e.g. in CdTe/Si or GaAs/Si systems.The aim of this work is to grow IV-VI layers directly on Si-substrates without any buffer layers to study the growth kinetics and epitaxial quality. PbSe was chosen as a representant of IV-VI materials, and layers were grown on (111)- and (100)-oriented silicon substrates.
Schottky Diodes on Si1-x-yGexCy Alloys.
Authors: Mamnor M. , Guedj C. , Boucaud P. , Meyer F. , Bouchier D. , Bodnar S. , Regolini J.L. 
Published: April 2011

ABSTRACTWe have recently investigated the properties of W/Si1-xGex films prepared by rapid thermal chemical vapor deposition (RTCVD). The barrier height on p-type, ΦBp, varies as the band gap with the germanium content for totally relaxed films, and increases with strain relaxation, while that on n-type remains rather constant. These results suggest that the Fermi level is pinned relative to the conduction band at the interface of the binary alloy and that the measurement of Schottky barriers is a suitable tool to follow band gap variations. In this work, the effects of carbon incorporation on Schottky barriers have been investigated. The study has been performed on Si1-x-yGexCy films (0≤y≤1.35% with x=10%). The strain retained in the films was determined by X-ray diffraction. Infrared absorption measurements have shown that the carbon is incorporated on substitutional sites. The electrical results indicate the same trends than those observed on the binary alloys, the barrier height on n-type remains rather constant while the barrier height on p-type varies. Adding C leads to an increase of ΦBp, but this increase is too large to be explained in terms of variation of the band gap. The influence of other parameters, such as the doping level and the hole effective mass is discussed.
Phase Separation In III-V Semiconductors
Authors: Hsieh K. C. , Cheng K. Y. 
Published: April 2011

ABSTRACTData are presented to show the morphological instability as well as the occurrence of 1-dimensional phase separation through the spinodal decomposition process in the strained layer heteroepitaxy of short-period superlattices. Biaxial strain has been attributed to be the driving force. With a large net strain in the epitaxial film, > 3.5%, island growth of (InAs)1/(GaAs)1 on GaAs is observed. With a near zero net strain, however, 1-dimensional lateral compositional modulation is observed in the growth of (InAs)2/(GaAs)2 on InP and (InP)2/(GaP)2 on GaAs substrates. Both surface reaction and bulk diffusion take part in forming the ultimate modulation. A small but definitive hydrostatic strain in the metastable Al0.3Ga0.7As film grown at low temperature induces also a 1-dimensional compositional modulation upon annealing at 600°C, a direct evidence of the existence of a miscibility gap in strained AlxGa1-xAs.
Strained Layer Epitaxy on Rough Si Surfaces
Authors: Lowes T.D. , Zinke-Allmang M. 
Published: April 2011

ABSTRACTLattice mismatch associated with heteroepitaxy imposes a significant limitation on the epitaxial compatibility between overlayer and substrate. In lattice mismatched systems the misfit may be accommodated to some extent by strain. However, in order to maintain misfit strain and avoid dislocation generation the epitaxial layer must not exceed a critical thickness. Some success has been reported in avoiding damaged epitaxial layers with thicknesses greater than the critical thickness by overgrowing on patterned or rough surfaces. For the case of Si, surface roughening by energetic Ar+ bombardment as a pre-growth roughening treatment is discussed and assessed. Evolution of surface features as a function of initial substrate treatment, ion accelerating potential, and the duration of bombardment are presented. Stability of the surface features generated by bombardment for typical overgrowth conditions was tested to assess feasibility of this technique for Si heteroepitaxy.
Photoluminescence Characterization of SiGe/Si Quantum-Well Wire Structures
Authors: Nilsson S. , Zeindl H. P. , Wolff A. , Pressel K. 
Published: April 2011

ABSTRACTLow-temperature photoluminescence measurements were performed in order to probe the optical quality of SiGe/Si quantum-well wire structures fabricated by electron-beam lithography and subsequent reactive ion etching, having the patterned polymethylmethacrylate resist as an etch mask. In addition, one set of quantum-well wire structures was post-treated by means of annealing in a hydrogen environment. Our results show that even for the smallest wires of about 100nm in width, the wires exhibit phonon-resolved photoluminescence spectra, similar to that from the molecular beam eptitaxially grown SiGe single quantum well which was used as starting material for the patterning process. After the patterning process a new sharp peak appears in the photoluminescence spectra at 0.97eV in photon energy. Our investigation suggests that this feature is introduced by damage during the patterning process and most probably identical to the G-line, which previously was identified as originating from the dicarbon centre (substitutional carbon-interstitial carbon) in Si. This centre is known to be a very common endproduct of irradiating Si near room temperature which is the case at our patterning process.
Photoreflectance Study of Strained InAIAs/InP Structures
Authors: Hwang Jenn-Shyong , Chou W. Y. , Tyan S. L. , Wang Y. C. , Tung J. H. 
Published: April 2011

ABSTRACTWe have studied the photoreflectance spectra at 300 K from a series of strained In1−xAlxAs/InP (0.42<x<0.57) strained structures grown by molecular beam epitaxy. From the observed Franz-Keldysh Oscillation we evaluate the built-in de electric field and hence the surface potential under different strain. We found that the surface Fermi level is not pinned at midgap under different strainwhich results in contrast to AIGaAs and GaAs. In addition, from the observed dependence of the built-in electric field Fdc and surface potential barrier Vm on the top layer thickness, we conclude that the surface states are distributed over two separate regions within the energy band gap under different strain and the densities of the surface states are as low as (2,71α0.05)x 1011 cm−2 for the distribution near the conduction band and (4.29α0.05)x1011 cm-2 for the distribution near the valence band. The Fermi level is weakly pinned while the top layer thickness is within the characteristic region of each sample.
Grazing-Incidence X-Ray Diffraction Studies of the Relaxation Behavior in Galnas/GaAs Multilayers Grown on GaAs[001]
Authors: Rose Dirk , Pietsch Ullrich 
Published: April 2011

ABSTRACTThe depth profile of the defect structure in strained and partially relaxed Ga0.8In0.2As/GaAs[001] multilayers is investigated with the method of X-ray grazing-incidence diffraction. Both in-plane and out-of-plane parameters are obtained from the subsurface region between five and a few hundred nm.The strength of the method is demonstrated on a sample series with similar thickness of the Ga0.8In0.2As sublayers, ta, but with varying thickness of the GaAs barrier, tb.The degree of relaxation R is directly obtained from the angular position of the in-plane Bragg peaks. For decreasing ta the peak maximum shifts to smaller angles which indicates an increase of R. Additionally the peak width is enlarged. This is explained by the orientational distribution of strain-reduced microdomains which are formed during the relaxation process. Their average size is estimated from the shape of the truncation rods which are recorded at the angular position of the in-plane Braggpeaks. The resulting size of about 100nm is additionally verified by high-resolution X-ray diffraction. The existence of microdomains is caused by a cross-hatched network of 60° misfit dislocations which is confirmed by TEM-measurements.
Determination of the Bonding Configurations of Carbon Acceptors in InxGa1−xAs and AlxGa1−xAs
Authors: Pritchard R. E. , Newman R.C. , Wagner J. , Maier M. , Mazuelas A. , Ploog K.H. , Lane P.A. , Martin T. 
Published: April 2011

ABSTRACTThe local environments of CAs acceptors in InxGa1−xAs and AlxGa1−xAs have been determined from the localized vibrational modes (LVMs) of both isolated CAs impurities and H-CAs pairs using infrared (IR) absorption and Raman scattering techniques. In as-grown layers of InxGa1−xAs (x<0.1), a single LVM due to isolated CAs acceptors was observed. The introduction of hydrogen led to the formation of H-CAs pairs and a single A1−-mode (stretch) and a single A1+-mode (XH) were observed for the InxGa1−xAs layers. All the LVMs were identified with carbon in CAsGa4 cluster configurations implying that less than 5 % of the detectable carbon atoms were present in clusters incorporating one or more CAs-In bonds. For AlxGa1−xAs, five stretch modes and five X-modes of the H-CAs pairs were observed for 0<x<1 and each mode was assigned to configurations for which the originally unpaired CAs had 0,1,2,3 or 4 Al nearest neighbors. These results show that carbon does not appear to form bonds with In atoms for the InxGa1−xAs samples investigated and this can explain the difficulty found in incorporating CAs acceptors in InxGa1−xAs with x>0.1 for some growth techniques. CAs acceptors can form strong bonds with both Al and Ga atoms, however, leading to a high solubility of carbon in AlxGa1-xAs over the full compositional range.
Low Temperature Grown Thin Inalas Step Graded Buffers for Application on Optical Modulator at 1.3 μM
Authors: Shen Lei , Wieder H. H. , Chang W. S. C. 
Published: April 2011

ABSTRACTPreliminary results are described about the growth, structure and properties of multiple quantum well(MQW) Quantum Confined Stark Effect (QCSE) modulators grown on GaAs substrates for operation at 1.3μm in wavelength. Step graded InAlAs buffer layers grown at low temperature by molecular beam epitaxy (MBE) with a total thickness of 0.3 μm are used to relieve the strain caused by the lattice-mismatch between the GaAs substrate and the In0.35Ga0.65As/In0.35Al0.65As MQW heterostructure. X-ray diffraction spectra show that significant lattice relaxation takes place in the buffer. A quantum confined Stark shift of the exciton absorption peak of 48meV was obtained with an applied electric field of 130KV/cm, measured in PIN diode structures consisting of 30 period 95ÅIn0.35Ga0.65As/100ÅIn0.35Al0.65As MQWs on a 3 stage compositionally step graded InxAl1−xAs buffer doped with Si to 5*1017/cm3 grown on a nominally 1018/cm3 n-type doped GaAs substrate.
Study of Highly Strained Single InAs−In0.53Ga0.47As Quantum Wells from Phonon Modes by Raman Scattering
Authors: Quagliano L. G. , Orani D. , Ricci A. , Simeone M. G. , Bruni M. R. 
Published: April 2011

ABSTRACTWe report Raman study of highly strained single InAs−In0.53Ga0.47As quantum wells grown by molecular beam epitaxy (MBE) on InP substrates with the well thickness between 4 and 15 monolayers. We have used Raman spectroscopy to characterize quality, disorder and strain of these structures which are of considerable interest for long wavelength optical communications.In the Raman spectra we have observed an intense narrow line corresponding to the GaAslike LO mode of In0.53Ga0.47As cap layer and a narrow peak due to the LO phonon mode of the InAs layer. These dominant and sharp features characterize the high homogeneity of our samples. In addition to these features we have observed the appearance of distinct peaks with the increase of the InAs layer thickness. In our opinion the presence of these modes is indicative of a slight deterioration of the structural perfection of the sample with the increase of the well thickness. Our investigation shows the ability of Raman spectroscopy to describe these systems and the good quality of our structures.
Measurement and Control of The Indium Composition Profile Near The InGaAs on GaAs Interface During Mbe
Authors: Kaspi Ron , Evans Keith R. 
Published: April 2011

ABSTRACTThe compositional abruptness at both the normal and the inverted InGaAs/Ga(Al)As interface is inherently limited by the surface segregation of In atoms during molecular beam epitaxy. We find, for example, that the intended alloy composition in In0.22Ga0.78As layers is not reached until nearly 35 Å from the normal InGaAs on GaAs interface for growth at 500 °C. We propose and demonstrate a scheme to control and eliminate the compositionally graded region at the normal interface by the artificial formation of an In surface segregated layer (predeposition) prior to the growth of InGaAs.
Mbe Growth and Characterization of (GaAs)l−x(Si2)x and (GaAs)1−x(Si2)x/GaAs Superlattices on GaAs Substrates
Authors: Lee H.P. , Szalkowski F.J. , Zeng X. , Wolfenstine J. , Ager J. W. 
Published: April 2011

ABSTRACTLateral compositional graded (GaAs)1-x(Si2)x alloys were deposited on GaAs substrates in a III-V molecular beam epitaxy (MBE) chamber equipped with a electron-beam Si evaporation source. Single crystal GaAs-Si alloys were formed when the deposition temperature was 600°C or higher. The alloys were characterized by Energy Dispersive X-ray Spectroscopy (EDS), Raman scattering measurement and cross-sectional Transmission Electron Microscopy (XTEM). Dislocation-free (GaAs)1-x(Si2)x films of up to x = 0.07 were deposited. For alloys with x between 0.15 < < 0.25, the morphology deteriorates and a high density of stacking faults and micro-twins were observed.
Progress in Modelling Plasma Etch Processes
Authors: Zarowin C. B. 
Published: April 2011

AbstractThis is a progress report on modelling the first of two aspects of plasma assisted chemical processes; it is shown here that by maintaining a constant plasma geometry, observable plasma parameters can be made to determine ion assisted surface chemistry uniquely because the mean energy of ions bombarding the reacting surfaces are thus also uniquely determined. Furthermore, the theory (1) given here sets the stage for another, given elsewhere (2), whicn shows that the resulting processes (i.e., reactive ion or plasma assisted etching and deposition) follow the same “rules”, as thermally driven cnei.lical vapor transport (CVT) for a fixed mean ion energy. Together, these theories permit a considerably more orderly understanding and application of plasma etch/deposition processes than has oeen previously possible.
Microfabricated Tem Sections
Authors: Deckman H. W. 
Published: April 2011

AbstractA simple convenient technique is described for fabricating 25-5,000Å sized microstructures which are suitable for use as thin sections in transmission electron microscopy. Microstructures are produced by reactive ion beam etching (RIBE) a submonolayer colloidal particle mask, and several effects seen in RIBE are discussed. In particular, it is shown that polymeric deposits formed on vertical side walls can be imaged and etch rates near the surface of some materials can differ substantially from the bulk. The microfabrication technique affords a simple method to study the internal structure of thin deposited films and use of the technique is illustrated with structural studies of amorphous semiconductor superl atti ces.
The Application of Reactive ion Etching to Oxide Films on 150mm Substrates
Authors: Dunfield Stephen , Deacon Tom , Pandhumsoporn Tam 
Published: April 2011

AbstractThe application of reactive ion etching to oxide films on 150mm sub-strates was studied. Etch rates of greater than 450 Å/min for thermal oxide with overall uniformities of less than ±5% have been observed. Selectivity of thermal oxide to polysilicon (20ω per square) has been observed to be in the range of 14:1 to 17:1.
Diagnostics for Process Plasmas
Authors: Dylla H. F. , Manos D. M. 
Published: April 2011

AbstractThis paper reviews the current state-of-the-art of several diagnostic techniques for characterizing, monitoring, and optimizing the properties of process plasmas. The plasma parameters of plasma configurations which are useful for materials processing, such as dc and rf glow discharges, are similar to the parameters of the boundary plasmas in magnetic fusion devices. As a result, much of the large development effort over the last decade on plasma diagnostics for boundary plasmas has direct application in process plasma systems. As particular examples, the authors discuss recent developments of: (1) electrostatic probes for electron density, temperature and power flow measurements; (2) laser fluorescence spectroscopy for ion density and flux measurements; and (3) quantitative plasma mass spectroscopy using quadrupole mass filters.
Spectroscopic Ellipsometry Study of rf-Sputtered a-Ge Films
Authors: Blanco J. R. , Messier R. , Vedam K. , McMarr P. J. 
Published: April 2011

AbstractSputtered amorphous germanium films have been examined by spectroscopic ellipsometry. a technique known to yield the void fraction in the bulk of the film,. (and hence a measure of density, ρcalc) with a high degree of precision, Considering the commonly accepted values of the dielectric function and the directly measured density, ρexpt, of Paul, Connell and Tomkin (1973), as the reference data, we reportf that ρcalc for some a-Ge films can be greater than that of crystalline Ge. Examination of the top surface of the sputter deposited films indicates that the highest densities are achieved under conditions of high energy ion bombardment of the film. This study indicates that a more detailed microscopic model of the structure of a-Ge must be considered.
Plasma Deposited Carbosilicon Films from Silane-Phenylsilane Mixtures
Authors: Cutro J. A. , Haller Ivan 
Published: April 2011

AbstractA series of amorphous silicon/carbon films were deposited from an RF glow discharge in silane-phenylsilane feed gas mixtures with the (ΦSiH3 content varying from 0 to 100 %. The films were characterized with optical and electrical measurements. While the structure of the films deposited from the mixtures contains carbon in more than one configuration the amount of pendant phenyl groups increases as the phenylsilane content of the feed gas is increased. The optical gap, derived from Tauc plots of the absorption spectra, ranges from 1.7 to 2.9 eV, while the refractive index obtained from ellipsometry, ranges from 3.7 to 1.8. The optical gap was found to vary linearly with the carbon atomic fraction in the feed gas, independent of the configuration of carbon atoms in the solid. The refractivity, (n2− 1)/(n2 + 2) , was found to exhibit a similar composition dependence. The room temperature resistivity was observed to increase sharply with increasing carbon content, rising from 107 ohm-cm to 1016 ohm-cm as the ΦSiH3 content of the feed gas was increased from 0 to 25 per cent.
Plasma Deposition of a-Si:H
Authors: Knights John C. 
Published: April 2011

AbstractThere are four easily identified stages in the formation of a hydrogenated amorphous silicon film from an electrical discharge in silane. The first stage is the primary reaction between electrons and silane resulting in a mixture of ions and free radicals. The second stage is the transport of these species to the substrate surface accompanied in parallel by a multiplicity of secondary reactions e.g. ion-molecule, photon-molecule, etc. The third stage is the reaction or adsorption of these species with or onto the substrate surface and the fourth stage is the process by which these species or their reaction products incorporate into the growing film or are reemitted from the surface into the gas phase.
Thermal Nitridation of Silicon in Active Nitrogen
Authors: Giridhar R. V. , Rose K. 
Published: April 2011

AbstractThe dissociation of N2 in a microwave discharge has been studied using a gas phase titration between N(4S) and NO. SF6 added in small concentrations (20–100 ppm of N2) is shown to be an efficient catalyst for dissociating N2. Dissociation fractions [N]/[N2 ] of 4–5% have been obtained. The studies suggest how the partial pressure of atomic nitrogen can be maximized. These results have been applied to thermal nitridation of Si in active nitrogen. A strong dependence of the film thickness on the partial pressure of atomic nitrogen (PN) has been shown. In addition to the nitridation rate, the nitrogen fraction [N]/([N] + [O]) also increases with PN.
The limits of patterning in X-ray lithography
Authors: Cerrina F. 
Published: April 2011

ABSTRACTWe show how the imaging process in proximity X-ray lithography is capable of reaching the sub-100 nm range. However, The use of proximity X-ray lithography is dependent on the mask to form the correct image of the pattern. The joint development of electron beam lithography patterning tools with high-placement accuracy, of a better understanding of the mask mechanical response and of new aligners, clearly indicates that the goal of using X-ray lithography for nanolithography applications is reachable.
Low Thermal Budget Processing Of Organic Dielectrics
Authors: Sharangpani R. , Singh R. , Cherukuri K. C. , Thakur R.P.S. 
Published: April 2011

AbstractLow dielectric constant organic materials are ideal for use as interconnect dielectrics forintegrated circuits. As compared to silicon dioxide, organic dielectrics with K <3.84 reducepower dissipation, crosstilk and RC delays in interconnects. Curing is essential afterdeposition of these materials to initiate polymerization reactions and form films of desirableelectrical properties. For high performance and reliability, low thermal budget processing isa necessity. Rapid isothermal processing (RIP) based on the use of dual spectral sources isa potential technique to lower the thermal budget. In this paper, we demonstrate the role ofphotoeffects in the curing of polyimide films (K∼2.6) using a rapid isothermal processor witha dual spectral source (Tungsten Halogen and vacuum ultra violet (VUV) lamps) as a sourceof optical and thermal energy. Lamp configurations that allowed a greater availability of ultraviolet and vacuum ultra violet photons on the film to initiate physical and chemical processesallowed a lower curing temperature to achieve the same level of immidization. Furthermore, these samples also gave the lowest leakage current and film stress. Therefore, the rapidheating and cooling features of rapid isothermal processing in conjunction with lowerprocessing temperature through the use of high energy photons to enhance surface reactionsgive superior film properties
Low Dielectric Constant Polymers For On-Chip Interlevel Dielectrics With Copper Metallization
Authors: Gutmann Ronald J. , Chow T. Paul , Duquette David J. , Lu Toh-Ming , Mcdonald John F. , Murarka Shyam P. 
Published: April 2011

AbstractLow dielectric constant insulators offer the potential of improved interconnection delay and conductor packing density in advanced ICs, both with current metallization schemes and with future technologies such as copper. While polymer materials are very promising in such applications, significant issues must be addressed before oxide-based materials are replaced in mainstream applications. This invited paper reviews the directions of our program, which has emphasized the use of vapor deposited polymers compatible with uniform deposition over large diameter wafers and copper metallization. Therefore, emphasis is placed on polymer material characteristics compatible with inlaid metal (ie. Dual Damascene) patterning.