bluuebunny/crossref_metadata_2025_split huggingface dataset:
Point-Defect Migration in Crystalline Si: Impurity Content, Surface and Stress Effects
Authors: Coffa S. , Libertino S. , La Magna A. , Privitera V. , Mannino G. , Priolo F. 
Published: April 2011

ABSTRACTThe results of several recent experiments aimed at assessing the room temperature migration properties of interstitials (D) and vacancies (V) in ion implanted crystalline Si are reviewed. We show that combining the results of ex-situ techniques (deep level transient spectroscopy and spreading resistance profilometry) and in-situ leakage current measurements new and interesting information can be achieved. It has been found that at room temperature I and V, generated by an ion beam, undergo fast long range migration (with diffusivities higher than 10−1 cm2/sec) which is interrupted by trapping at impurities (C, O) or dopant atoms and by recombination at surface. Analysis of two-dimensional migration of point defects injected through a photolithographically defined mask shows that a strong I recombination (characterized by a coefficient of 30 μm−1) occurs at the sample surface. Moreover, we have found that the strain field induced by an oxide or a nitride mask significantly affects defect migration and produces a strong anisotropy of the defect diffusivity tensor. Finally, using in-situ leakage current measuremens, performed both during and just after ion irradiation, the time scale of point defect evolution at room temperature has been determined and defect diffusivities evaluated. The implications of these results on our current understanding of defect and diffusion phenomena in Si are discussed.
Epitaxially Grown N+ Phosphorus Collector Peaks In Highfrequency hbt's with Implanted Emitters
Authors: Visser C. C. G , Nanver L. K. , Bogaard A. Van Den 
Published: April 2011

AbstractThe boron out-diffusion into the Si collector of SiGe HBT's with implanted emitters is compensated by an epitaxially grown n+ phosphorus peak effectively positioned adjacent to the as-grown boron peak. Detrimental barrier formation is suppressed in devices with base sheet resistance 3.3 k.Ω and cut-off frequency of 31 GHz.
Characterization of SiGeC Using Pt(SiGeC) Silicide Schottky Contacts
Authors: Peterson Jeff J. , Hunt Charles E. , Robinson McDonald , SCott Robin 
Published: April 2011

AbstractMaterial and electrical characterization of n-type and p-type Si1-x-yGex Cy epitaxial layers on Si(100) was performed using silicided platinum Schottky contacts. XRD studies show Pt silcidation of SiGeC proceeds from non-reacted Pt to Pt2(SiGeC) and completes with the Pt(SiGeC) phase similar to Pt/Si silicides, but Pt silicide reactions with SiGeC are shown to require higher temperatures than Pt reactions with Si. Electrical characterization of Pt(SiGeC) contacts to n-type Sil1-x-yGexCx/Si shows rectifying behavior with constant barrier heights of 0.67eV independent of composition, indicating Fermi level pinning relative to the SiGeC conduction band is occurring. Pt(SiGeC) contacts to p-type Si1-x-yGexCy/Si are also rectifying with barrier heights that track the variation of the SiGeC energy bandgap.
Ellipsometry Studies, Optical Properties, And Band Structure of Gel.1-yCy, Ge-RICH Si1-x-yGexCy, And Boron-Doped Si1-xGexAlloys
Authors: Junge Kelly E. , Lange Ruidiger , Dolan Jennifer M. , Zollner Stefan , Humlfcek Josef , Dashiell M. W. , Hits D. A. , Orner B. A. , Kolodzey James 
Published: April 2011

AbstractWe measured the pseudodielectric function (PDF) of Ge1-yCy and Ge-rich Si1-x-yGexCy alloys from 1.1 to 5.2 eV using spectroscopic ellipsometry. These alloys were grown by molecular beam epitaxy at 6000C on (001) Si substrates. Analytical lineshapes fitted to numerically calculated derivatives of their PDFs determined the critical-point parameters of the E1, E1+Δ1, E0', and E2 transitions. The critical-point energies of the Ge1-yCy alloys were found to be similar to bulk Ge. This indicates that the presence of C in these alloys only has a small influence on the band structure. For some samples, the amplitude of the PDF is much lower than in bulk Ge, which can be attributed to surface roughness and explained within the framework of the Kirchhoff theory of diffraction or using effective medium theory. The degree of surface roughness indicated by optical measurements was confirmed by atomic force microscopy. We also studied bulk Czochralski-grown Si1-xGex alloys (0<x<0.28) doped with boron. Due to doping, the critical points shift to lower energies as reported previously for bulk Si and Ge.
Light Emission From Erbium Doped Si1-x XGe1Heterostructures
Authors: Evans-Freeman J H , Naveed A T , Huda M Q , eaker A R , oughton D C , right A C 
Published: April 2011

AbstractUHVCVD-grown SiO.s 7Ge0.13/Si heterostructures have been implanted with erbium, and photoluminescence and electroluminescence centred on 1.54ýim have been studied. Implantation conditions were chosen so that the erbium concentration profile was flat over the spatial location of the SiGe quantum well region. We demonstrate that the technology of implantation and regrowth is feasible even when Si/SiGe interfaces are present. We have obtained more intense photoluminescence from erbium implanted SiGe heterostructures than that from a silicon layer implanted with a higher erbium dose. We report forward bias electroluminescence from the Er doped SiGe/Si heterostructures; the photoluminescence and electroluminescence from these structures demonstrates that the detailed mechanism of excitation is different from the Er:Si case.
Effect of Interface-Related Deep Levels on high Sensitivity of Schottky Diode Photodetector Based on Ultrathin InGaAs Film on Si
Authors: Kvit A. V. , Yakimov M. V. , Konstantinov P. L. , Naidenkov M. N. 
Published: April 2011

AbstractRecently, the Fermi level has been demonstrated to be pinned in GaAs semiinsulating ultrathin (<100 A) films grown at low temperatures [1]. This allows one to construct a detector with “internal” photocurrent amplification. The amplification effect compensates losses in sensitivity due to the small width of light-sensitive layer which absorbs 10 — 50 % of incident radiation. We fabricate photodetector structures with external quantum efficiency more than 1 for visible region. Photogenerated carriers in the GaAs layer are effectively separated by the built-in electric fields formed by the Schottky barrier and by the charge at the GaAs/Si interface. In this work, we show the relationships between spectral sensitivity of the metal-InGaAs/Si structures and In content. We observed the red shift in the photocurrent spectra with increasing In concentration, although photosensitivity of such structures dropped drastically. This shift demonstrates that the thin InGaAs film is actually responsible for photosensitivity. Despite the low photoluminescence intensity, the lowtemperature PL spectra indicate that band gap decreases with indium flux rising during MEE growth. The surprise was that the decrease of the film thickness caused the increase of photosensitivity. The GaAs(20 A)-InGaAs (20 A)/Si structure was the most sensitive one. We also observed high quantum efficiency in near-UV region (up to 0.8). We determined activation energy of elctron and hole traps and their concentration profiles by DLTS. The centers localized on interface between polar and nonpolar semiconductors are responsible for Fermi-level pinning in III-V semiinsulating materials and act as an electron trap with activation energy 0.59 eV. The origin of deep levels is discussed.
Using Growth Kinetics for Nanoengineering of Si-Ge Surfaces
Authors: Goldfarb I. , Briggs G. A. D. 
Published: April 2011

AbstractIn this work we explore how various growth characteristics of Ge on Si(001) can be used to fabricate structures for potential nanodevices. In the first example, the self-assembling tendency of germanium for three-dimensional islanding on Si(001) is considered, e.g. for application in devices based on quantum dots and wires. We aimed at achieving a detailed understanding of dot nucleation and growth mechanisms from germane. By controlling the deposition parameters, such as the germane pressure and substrate temperature, arrays of dots and antidots can be created on the grown surface, and further modified by post-deposition anneals. While lower temperature deposition leads to randomly distributed dots (i.e. small and coherent three-dimensional clusters with pyramidal shapes), a higher temperature deposition results in formation of antidots (i.e. pyramidal pits), which, in turn, are gradually replaced by the clusters, if the deposition is allowed to continue. The difference is caused by the different hydrogen behaviour at the respective temperature ranges. The germanium tendency to incorporate preferentially at the step and island edges is another beneficial property, which can be used to align the dots along step edges, creating wires rather than dots, or to fabricate ultrasmall Si-Ge heterojunctions, of a less than 10 nanometer size.
Toward RF System-Level Integration: Process Integration Issues in Sige BICMOS
Authors: Freeman G. , Schonenberg K. , Ahlgren D. , Jeng S-J. , Nguyen-Ngoc D. , Stein K. , Colavito D. , Subbanna S. , Harame D. , Meyerson B. 
Published: April 2011

AbstractThe SiGe HBT, integrated with CMOS devices on the same chip, will be the first integrated device combination to realize the long-standing technology goal of fabricating RF systems on a chip. It has been demonstrated that the HBT device can replace the standard GaAs front-end of RF systems and take advantage of the reduced cost available from Si technologies in 200–300mm wafers. However, the SiGe HBT can only be part of a large-scale RF system on a chip when, in the same technology, NFETs and PFETs are provided for low power, low frequency digital logic, and a suite of resistors, capacitors, diodes, and inductor passive elements are provided for the high frequency analog circuitry. Furthermore, all these elements must be manufacturable defect-free at medium and high levels of integration.This paper covers keyprocess integration issues confronting technologists when integrating a SiGe HBT device with the requisite CMOS and passive elements and at the same time maintaining very high GaAs-like performance. Topics to be discussed are 1) a review of high-performance HBT device integration schemes employed to date and integration issues with each scheme, 2)integration issues in epitaxial cleaning and growth techniques, 3) integration issues influencing crystal defects, and 4) integration issues with passive elements. Status of the IBM SiGe BiCMOS technology will be presented to illustrate the first successful integration of this set of devices into
a manufacturable process.
The Application of Novel Chemical Precursors for the Preparation of Si-Ge-C Heterostructures and Superlattices
Authors: Nesting David C. , Kouvetakis John , Lorentzen Julie , Menéndez José 
Published: April 2011

AbstractWe have investigated new synthetic methods to Si-Ge-C materials by UHV-CVD and novel chemical precursors. The reactions of (SiH3)4C and (GeH3)4C with GeH4 and SiH4 produce diamond structured materials with the general formula (CSi4)xGey and (CGe4)xSiy respectively. These reactions demonstrate the application of novel C-H free precursors that incorporate Si4C and Ge4C building blocks to prepare single phase materials containing a significant amount of carbon (5–6 at.%). They also indicate the remarkable degree of compositional control provided by the precursor to incorporate the Si4C and Ge4C molecular framework into the solid state. A range of Si1-x-yGexCy compositions were also prepared pseudomorphically on [1 0 0] Si at 450–500 °C via reactions of (SiH3)4C with mixtures of GeH4 and Si4. The (Si2Ge)31C6 composition appears to display ordering of the Ge and Si atoms in the structure. The incorporation of C in the Si planes seems to provide local strain centers which facilitate the formation of this ordered phase.
Limitations to the use of Sb as a Surfactant During SiGe MBE
Authors: Jernigan Glenn G. , Silvestre Conrad L. , Fatemi Mohammad , Twigg Mark E. , Thompson Phillip E. 
Published: April 2011

AbstractThe use of Sb as a surfactant in suppressing Ge segregation during SiGe alloy growth was investigated as a function of Sb surface coverage, Ge alloy concentration, and alloy thickness using xray photoelectron spectroscopy, x-ray diffraction, and transmission electron microscopy. Unlike previous studies where Sb was found to completely quench Ge segregation into a Si capping layer, we find that Sb can not completely prevent Ge segregation while Si and Ge are being co-deposited. This results in the production of a non-square quantum well with missing Ge at the beginning and extra Ge at the end of the alloy. We also found that Sb does not relieve strain in thin films but does result in compositional or strain variations within thick alloy layers.
Carrier Transport and Velocity Overshoot in Strained Si On Sige Heterostructures
Authors: Ferry David K. , Formicone Gabriele , Vasileska Dragica 
Published: April 2011

AbstractWe examine the velocity overshoot effect in strained Six on Six-Ge1-x heterostructures. We also investigate the performance of surface-channel strained-Si MOSFETs for devices with gate lengths representative of the state-of-the-art technology. The Ensemble Monte Carlo method, self-consistently coupled with the 2D Poisson equation solver, is used in the investigation of the device performance. Our simulations suggest that, in short-channel devices, velocity overshoot is very important. In fact, when velocity overshoot occurs, it greatly affects the carrier dynamics and the current enhancement factor of both surface-channel strained-Si and conventional Si MOSFETs.
Loading Effects During Low-Temperature Seg Of Si And SiGe
Authors: De Boer W. B. , Terpstra D. , Dekker R. 
Published: April 2011

AbstractSelective Epitaxial Growth (SEG) of Si and SiGe suffers from pattern sensitivity. The growth rate and layer composition change with the pattern and the window size. In relation to growth at atmospheric pressure, the sensitivity to the window size is suppressed at reduced pressure, whereas some growth rate effects of a more global nature become more visible. The Si growth rate decreases when the area of exposed silicon on the wafer and the susceptor decreases. SiGe shows the opposite behavior: its growth rate increases with decreasing silicon area. Another difference between Si and SiGe is the range over which the loading effects are active. The influence of a large silicon area on the Si growth rate can be felt inches away, whereas the SiGe growth rate is affected over a much shorter distance. In common epi reactors the wafer rests on a susceptor, which extends beyond the wafer, exposing a large Si-coated surface area around the circumference of the wafer. Consequently, the Si growth rate varies unacceptably across the wafer. A sacrificial polysilicon layer has been successfully applied to improve the growth rate uniformity across the wafer.
A Selective/Non-Selective Epitaxy Process For A Novel Sige Hbt Architecture
Authors: Schiz J. , Bonar J. M. , Shburn P 
Published: April 2011

AbstractA selective/non-selective epitaxy process for a novel self-aligned SiGe HBT structure is described. It is shown that damage in the silicon substrate induced by reactive ion etching can be effectively removed and that this allows the growth of high quality selective and nonselective epitaxy. Control of the base thickness and doping can be maintained during selective and non-selective epitaxy, thereby demonstrating the feasability of producing the self-aligned HBT structure.
Photoluminescence Of Sisnc Alloys Grown On (100) Si Substrates
Authors: Wright N. , Khan A.T. , Berger P.R. , Guarin F.J. , Iyer S.S. 
Published: April 2011

AbstractPhotoluminescence (PL) of SiSnC alloys grown on Si (100) substrate by molecular beam epitaxy (MBE) has been investigated. The following epitaxial layers were investigated. The samples were similar in structure, and consisted of a 200 Å Si buffer layer grown on a (100) Si substrate followed by the respective alloy layer; a 4500 Å Si0.955Sn0.03C0.015, a 1500 Å Si0.9Sn0.04, or a 1500 Å Si0.985C0.015. The layer composition was measured by Rutherford back scattering spectrometry (RBS) and confirmed by x-ray diffraction analysis (XRD). X-ray diffraction measurements of the layers confirmed the Sn and C were substitutional and the layers were pseudomorphic and coherently strained. The Si0.955Sn0.03C0.015 alloy layer was found to be strain compensated. PL spectra of all the layers revealed band edge luminescence as well as a very sharp peak at 0.767 eV superimposed on a very broad peak that exhibited excitonic behavior. The addition of C to the alloys resulted in a reduction of the bandgap, contrary to what is predicted by Vegard's Law. However, the addition of Sn results in a reduction in the bandgap, which was attributed to the bulk alloy effect and residual strain. The luminescence feature at 0.767 eV was found to be much more intense in alloys that contain carbon. We have observed quite similar deep-level well resolved PL spectra for SiGe, SiC, SiSn, SiGeC, SiSnC, and SiGeSnC alloy layers grown by MBE on Si (100) substrates. Previous studies on PL of silicon have reported a peak at 0.767 eV to be associated with oxygen (P line) and the broad peak to carbon/oxygen complexes.
Growth and Characterization of Epitaxially Stabilized Pseudomorphic α-Sn/Si Heterostructures
Authors: Min Kyu Sung , Atwater Harry A. 
Published: April 2011

AbstractGrowth and structural characterization of ultrathin, coherently strained oc-Sn/Si quantum well heterostructures have been performed. Severe Sn segregation to the surface during growth, which prevents growth of these structures at ordinary Si epitaxy temperatures, has been minimized by substrate temperature and growth rate modulations during molecular beam epitaxy. Single Sn/Si quantum wells grown with Sn coverage up to 1.4 ML have been verified to be pseudomorphic by transmission electron microscopy and X-ray rocking curve analysis. Similarly, pseudomorphic superlattices with up to 10 periods of 1 ML Sn/7.7 nm Si have been verified to be free of extended defects.
Single Crystal Gd203 Films Epitaxially Grown on GaAs - A New Dielectric for GaAs Passivation
Authors: Hong M. , Kwo J. , Kortan A. R. , Mannaerts J. P. , Wu M. C. , Lay T. S. , Sergent A. M. 
Published: April 2011

AbstractSingle crystal Gd2O3 dielectric thin films were epitaxially grown on GaAs. The Gd2O3 film has a cubic structure isomorphic to Mn2O3, and is (110) oriented in single domain on the (100) GaAs surface. The oxide film has low leakage current densities ˜ 10–9 – 10–10 A/cmT2 at zero bias. Typical breakdown field is 4 MV/cm for an oxide film 185 Å thick, and >10 MV/cm for an oxide less than 50 Å thick. Both accumulation and inversion layers were observed in the Gd2O3-GaAs metal oxide semiconductor (MOS) diodes using capacitance-voltage (C-V) measurements, with an interfacial density of states around 1011 cm–2 eV–1.
Lattice Engineering Using Lateral Oxidation of Alas: an Approach to Generate Substrates With New Lattice Constants
Authors: Chavarkar P.M. , Zhao L. , Keller S. , Black K.A. , Hu E. , Speck J. , Mishra U. 
Published: April 2011

AbstractWe demonstrate a new approach to the growth of dislocation free lattice-mismatched materials on GaAs substrates using Al2O3 interlayers obtained by lateral oxidation of AlAs. This is achieved by generating relaxed low threading dislocation density InGaAs templates which are mechanically supported but epitaxially decoupled from the host GaAs substrate. This process uses the phenomena of relaxation of strained coherent hypercritical thickness (h > hcritical,) layer in direct contact with an oxidizing Al-containing semiconductor (i.e. AlAs or AlGaAs). 5000 Å In0.11Ga0.89As layers were then grown on the In0.2 Ga0.8As/Al2O3/GaAs template which acts as a pseudo-substrate (lattice-engineered substrate). The epitaxial layers are partially relaxed and have extremely smooth surface morphology. Further TEM micrographs of these epitaxial layers show no misfit dislocations or related localized strain fields at the In0.2Ga0.8As/Al2O3 interface. The absence of misfit dislocations or local strain contrast at the In0.2Ga0.8As/Al2O3 interface is attributed to both reactive material removal during the oxidation process and the porous nature of the oxide itself. We propose that the strain relaxation in In0.3Ga0.7As is enhanced due to the absence of misfit dislocations at the In0.2Ga0.8As/A12O3 interface.
Growth of Improved GaAs/Si: Suppression of Volmer-Weber Nucleation for Reduced Threading Dislocation Density
Authors: Taylor P. J. , Jesser W.A. , Simonis G. , Chang W. , Lara-Taysing M. , Bradshaw J. , Clark W. , Martinka M. , Benson J.D. , Dinàn J.H. 
Published: April 2011

AbstractThe growth of reduced dislocation density GaAs/Si is performed by a novel two-step technique where the first epitaxy step takes place at 75° C and the second is performed at 580° C. The initial deposition is single crystal, continuous, and planar such that there is no contribution to the dislocation density from Volmer-Weber island coalescence and no trapping of dislocations in pinholes. Using this new growth technique, a reduced dislocation density the order of 106/cm2 was obtained. The improved crystallinity is indicated by the more narrow x-ray full-width-at-half-maximum (FWHM) value of 110 arcseconds. GaAs p-i-n diodes were grown on the reduced dislocation density GaAs/Si and it was found that the resistivity of the intrinsic region for the heteroepitaxial diodes was similar to homoepitaxial ones for small mesa sizes.
Strain Relaxation During Heteroepitaxy on Twist-Bonded Thin Gallium Arsenide Substrates
Authors: Kopperschmidt P. , Senz S T. , Scholz R. , Kästner G. , Gösele U. , Velling P. , Prost W. , Tegude F.-J. , Gottschalch V. , Wada K. 
Published: April 2011

AbstractWe realized “compliant” substrates in the square centimeter range by twist-wafer bonding of an (100) GaAs handle wafer to another (100) GaAs wafer with a several nm thick epitaxially grown GaAs layer followed by an appropriate back-etch procedure. The twist angle between the two GaAs wafers was chosen between 4 and 15 degrees. The twisted layers were characterized by area scanned X-ray diffraction, optical and electron microscopy and atomic force microscopy. Occasionally we observed regions showing pinholes in the transferred thin twistbonded GaAs layer.After epitaxial deposition of 300 nm InP and InGaAs films with different degrees of mismatch on these substrates, transmission electron microscopy revealed grains which are epitaxially oriented to either the substrate or the twist-bonded layer. The grain boundaries between the twisted and untwisted grains probably collect threading dislocations, thus reducing their density in the areas free of boundaries.