bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multilayer AlxGa1−xAs Heterostructures for Second-Harmonic Generation
Authors: Janz S. , Chatenoud F. , Dai H. , Vilks E. , Buchanan M. , Normandin R. , Springthorpe A. J. 
Published: March 2011

ABSTRACTQuasi-phase matching in AlxGa1−xAs heterostructure optical waveguides can be used for efficient second-harmonic (SH) generation. The efficiency of these devices depends on the linear and nonlinear optical properties of the component materials. We present measurements of the SH susceptibility variation in AlxGa1−xAs with Al concentration, for fundamental light at λ = 1.06 μ. The measured SH susceptibility decreases by an order of magnitude as the Al concentration is varied from x = 0 to x = 0.97. These measurements are used to evaluate the SH generation efficiency of AlxGa1−xAs heterostructures as the structural and material parameters are varied.
Vertical-Cavity Optoelectronic Structures: CAD, Growth, and Structural Characterization
Authors: Christensen D. H. , Crochiere S. M. , Pellegrino J. G. , Rai R. S. , Parsons C. A. , Tseng W. F. , Hickernell R. K. 
Published: March 2011

ABSTRACTSimulations of reflectance spectra and electric field distributions for vertical-cavity structures were used in the computer aided design of epitaxial mirrors and lasers. The binary GaAs/AlAs superlattice alloys and AlxGa1−xAs random alloys that compose these structures were grown by molecular beam epitaxy. Photoluminescence, photoreflectance, reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, and double crystal x-ray diffractometry were applied to characterize cavity and Bragg mirror layer thicknesses and alloy composition.
Optical Channel Waveguides in AlGaAs Multiple Quantum Well Structures Formed by Focused Ion Beam Induced Compositional Mixing
Authors: Kumar Mukesh , De Brabander Gregory N. , Chen Peter , Boyd Joseph T. , Steckl Andrew J. , Choo Ahn Goo , Jackson Howard E. , Burnham Robert D. , Smith Stephen C. 
Published: March 2011

ABSTRACTOptical channel waveguiding in AlGaAs multiple quantum well structures formed by compositional mixing implemented by focused ion beam (FIB) implantation is demonstrated. To achieve selective mixing, Si is FIB implanted with a dose of 5×1014 cm−2 followed by RTA at 950°C for 10 s. Raman microprobe spectra are used to characterize the lateral variation of mixing. Propagation loss in a channel waveguide is measured. Measurement of the waveguide mode field distribution allows for the determination of changes in refractive index due to mixing and an approximate mixing depth.
Enhanced photoluminescence from AlGaAs/GaAs superlattice gratings fabricated by Si FIB implantation
Authors: Steckl A. J. , Chen P. , Choo A. G. , Jackson H. E. , Boyd J. T. , Ezis A. , Pronko P. P. , Novak S. W. , Kolbas R. M. 
Published: March 2011

ABSTRACTResults are presented on the fabrication of optical gratings on an Al0.3Ga0.7As/GaAs superlattice (SL) with equal 3.5 nm barrier and well widths, by using locally FIB-enhanced mixing. As the first step, the mechanism of the mixing was studied. Si++ was accelerated to 50 kV and lOOkV and implanted at doses ranging from 1013 to 1015/cm2. A rapid thermal anneal of 10 s at 950°C was utilized. The average Al inter-diffusion coefficient and length were calculated as a function of FIB dose from SIMS depth profiling. The mixing was significantly enhanced by the FIB implantation. The ion dose as low as l×1014/cm2 followed by RTA yields a mixing parameter of ∼90% and results in a two-order of magnitude increase in the diffusion coefficient, to a value of 4.5×10−14cm2/sec, in contrast to 1.3×10−16cm2/sec from RTA-only. The maximum mixing occurred in the region where neither Si ions nor vacancies have their maximum concentration. Instead, it coincides with the location of the positive maximum of the second derivative of the vacancy concentration profile. This fact suggests that in the time frame of RTA and with low dose, the diffusion of nonequilibrium point defects plays a major role in the process of enhancing Al-Ga interdiffusion. DBR optical gratings, consisting of thousands of spacing lines with 350nm period, were fabricated with a lOOkV FIB dose of 2×1013 andl×1014/cm2. Photoluminescence (PL) spectra were taken from the grating region as well as the unimplanted superlattice region. The PL intensity from cavity region of the DBR was about 16 times higher than that from the original SL. This PL enhancement was verified to occur in the cavity region only by spatially scanning over the entire sample. A possible mechanism for this PL enhancement is optical feedback provided by the gratings.
Defect Reduction in GaAs Grown on Si by Using Saw-Tooth-Patterned Substrates
Authors: Zhu Jane G. , Al-Jassim M. M. , Karam N. H. , Jones K. M. 
Published: March 2011

ABSTRACTEpitaxial GaAs layers have been grown on saw-tooth-patterned (STP) Si substrates by metal-organic chemical vapor deposition and analyzed by transmission electron microscopy. The utilization of this special interface feature is effective in suppressing the formation of antiphase boundaries and reducing the threading dislocation density. The growth of GaAs has been studied with the epilayer thicknesses ranging from several hundred angstroms to several microns. Very flat growth front on (100) plane above the STP region is observed. The dislocation density decreases very rapidly in the area farther away from the interface. The dislocation configuration at this STP interface is very different from that at the extensively studied two-dimensional planar interface.
TEM Study of the Growth Modes in ALMBE GaAs Layers on Si
Authors: Vilà A. , Comet A. , Morante J. R. , González L. , González Y. , Briones F. , Ruterana P. 
Published: March 2011

ABSTRACTIn this work, we have compared, by using Transmission Electron Microscopy (TEM) techniques, the initial stages of epitaxial growth of GaAs on Si (100) by conventional MBE and ALMBE, trying to find the conditions necessary to achieve 2D growth at the earliest stage of deposition. Our results show that flat layers with a good surface coverage can be obtained by reducing the GaAs ALMBE deposition temperature down to 200°C.
Crystal Quality and Surface Morphology Improvement of Movpe-Grown GaAs-on-Si Using Tertiarybutylarsine
Authors: MIYAGAKI S. , Ohkubo S. , Takai K. , Takagi N. , Kimura M. , Kikuchi Y. , Eshita T. , Takasaki K. 
Published: March 2011

ABSTRACTWe developed GaAs heteroepitaxy on a Si substrate by metalorganic vapor phase epitaxy (MOVPE) using tertiarybutylarsine (TBAs). In buffer layer growth at 450°C, the surface morphology and crystal quality of TBAs-grown films were slightly inferior to those of AsH3-grown films. At buffer layer growth below 400°C, the quality of TBAs-grown films improved. The GaAs films we grew using TBAs had a better quality than those grown using AsH2.
Growth of InSb/GaAs Layers on YIG-Coated GGG Substrate
Authors: Jelen C. , Charrière S. , Razeghi M. , Leppert V. J. 
Published: March 2011

ABSTRACTWe report the first growth of InSb and GaAs epilayers upon a garnet (YIG = Y3Fe5O12) epilayer. The YIG was deposited using liquid phase epitaxy on a garnet (GGG = Gd3Ga5O12) substrate oriented in the [111] direction. The growth of the GaAs was carried out using laser ablation and no superlattice was used to buffer the lattice mismatch between YIG and GaAs. The growth of InSb was done by low-pressure metalorganic chemical vapor deposition. From x-ray diffraction analysis it was found that the GaAs and InSb were both (110) monocrystalline epitaxial layers.
SiGe Heterojunctions Transistors and Optoelectronic Devices
Authors: Arienzo Maurizio , Comfort James H. , Crabbe Emmanuel F. , Harame David L. , Iyer Subramanian S. , Kesan Vijay P. , Meyerson Bernard S. , Patton Gary L. , Stork Johannes M.C. , Sun Yuan-Chen 
Published: March 2011

ABSTRACTSiGe alloys have been successfully applied to a number of semiconductor devices, including bipolar heterojunction transistors, field effect transistors (FET's), and optoelectronic devices and structures. This review paper will first summarize the results obtained to-date in bipolar transistors, highlighting the design flexibility and the trade-offs offered by SiGe heterojunction technology and bandgap engineering, like junction field/capacitance control, liquid nitrogen operation and complementary processes. The leverage of this technology in high speed circuits will be discussed, including the record 75 GHz fr and 60 GHz fmax heterojunction bipolar transistors, the achievement of sub-25 ps ECL ring oscillator delay, and the doubling of the mobility in p-MODFETs. The applications of this technology to optoelectronic devices, including detectors and waveguides, will also be reviewed, to extend the use of silicon technology to long wavelength communication technology and infrared imaging.
Study of The Transversal Electron Mobility in Heterojunction Bipolar Transistors with Strained SI1−x Gex-Base
Authors: Poortmans J. , Caymax M. , Van Ammel A. , Libezny M. , Nijs J. 
Published: March 2011

ABSTRACTThe effective transversal mobility of the minority carrier electrons in asymmetrically strained p-type Si1−x Gex -layers, grown on a Si (100) substrate, is studied as a function of boron doping concentration and Ge-content x. The experiments are based on the temperature dependence (290 to 400K) of the collector current enhancement of heterojunction bipolar transistors with a pseudomorphic Si1−x Gex-base. The interpretation of these results is based on new insights about the effective density of states in the valence band of these strained layers [1]. We will present first experimental evidence of the theoretical calculations in [1]. From this we will derive then the value of the NcNv -product for the strained Si1−x Gex-alloy. This allows to extract the ratio of the electron mobility in Si and strained Si1−xGex. We found an enhancement of the mobility when the B-doping level is around 1018 cm−3 and 0.08<x<0.16. At higher values of the Ge-content and the doping level, the enhancement is reduced again.
Self-Compensation of Donors in GaAs Grown by MOCVD
Authors: Andreyev Gennady V. , Maslovsky Vladimir M. 
Published: March 2011

ABSTRACTThe variation of luminescence parameters with the tin dopant concentration is considered in GaAs epitaxial layers. It is shown that at typical growth conditions and absence of contamination the deep accepters are generated by self material so that the compensation coefficient (K=Na/Nd) of 0.25 is constant up to critical electron concentration of 2.1018cm−3. The self-compensation is realized by native point defect ofattice which is gallium vacancy. The gallium vacancy is arranged next to the every fourth donor at the distance of 7 A.
Degradation and Recovery of Boron Doped Strained Silicon Germanium Layers After 1-MeV Electron Irradiation
Authors: Ohyama H. , Vanhellemont J. , Trauwaert M.-A. , Poortmans J. , Caymax M. , Clauws P. 
Published: March 2011

ABSTRACT1007×100 μm2 n+− Si/p-Si1−x Gex diodes fabricated on conventional p-type Si substrates are irradiated at room temperature with 1-MeV electrons with fluences from 1.0×1014 to 1.0×1015 e/cm2 in a high voltage transmission electron microscope. The boron concentration and germanium fraction of the Si1−x Gex epitaxial layer used for the diodes in this study are 5×1017 cm−3 and x = 0.12, respectively. The degradation of diodes is investigated by means of current/voltage and capacitance/voltage measurements. The characteristics of the electrically active defects induced in the Si1−x Gex epitaxial layer by irradiation are also examined by using deep level transient spectroscopy and capacitance/temperature measurements. The degradation of the diode performance and the presence of deep levels are investigated as a function of electron fluence. In order to examine the recovery process, an isochronal thermal anneal is performed in the temperature range between 100 and 400°C.
Thermal Stability of the Structural and Electronic Properties of Strain Symmetrized Sim Gen Superlattices and Ungraded, Nearly Relaxed Si1−x Gex
Authors: Dafesh P. A. , Adams P. M. , Arbet-Engels V. , Wang K. L. 
Published: March 2011

ABSTRACTIn this study, photoreflectance (PR) spectroscopy and x-ray rocking curves measurements were used to study the variation in strain configuration, defect propagation, structural properties and direct electronic transition energies in Sim Gen superlattices (SL) and nearly relaxed Si1−x Gex buffer layers grown on < 100 > Si as a function of annealing temperature. The in-plane (a│) and perpendicular (a┴) lattice constants of the alloy buffer layers are found to vary only slightly with anneal temperature, TA, up to a temperature To. For TA To, the in-plane strain changed from roughly zero a│ ≈ a┴ (relaxed) or a┴ > a│ (compressive) to a┴ > a│ (tensile). This change in strain configuration is believed to be caused by the difference in thermal expansion coefficients between the epilayer and the Si substrate. The anneal temperature T0 is also correlated with the disappearance of higher order x-ray harmonics from the SL. This point was also correlated with a large energy shift and broadening of the PR spectra from the SL. The shift in energy of the PR spectra is explained in terms of the interdiffusion of Si and Ge at SL heterointerfaces, and to a lesser degree, the strain induced by the above mentioned difference in thermal expansion coefficients. The PR spectra of the alloy E0 transitions are also observed to shift to higher energy with increasing TA.
Broad Band vs Phonon Resolved Luminescence in Si1−xGex/Si Heterostructures Grown by Molecular Beam Epitaxy
Authors: Houghton D. C. , Rowell N. L. , Noel J.-P. , Dion M. M. , McCaffrey J. , Davies M. , Wang A. , Perovic D. D. 
Published: March 2011

ABSTRACTSi1−xGex alloys and multilayers synthesized by solid source MBE on Si(100) substrates have been characterized by low temperature photoluminescence (PL) spectroscopy and transmission electron microscopy (TEM). Phonon resolved transitions originating from excitons bound to shallow impurities were observed in addition to a broad band of intense luminescence. PL spectroscopy over the temperature range 2K to 100K has been used to characterize Si1−xGex/Si heterostructures exhibiting both types of PL spectra. Thin alloy layers exhibited phonon-resolved PL spectra, similar to bulk material, but shifted in energy due to strain and hole quantum confinement. In single quantum wells confinement shifts up to ∼200 meV were observed (1.2 nm wells with x = 0.38) and NP linewidths down to 1.37 meV were obtained. However, the broad PL band (peak energy ∼120meV below the strained bandgap) was predominant when the alloy layer thickness was greater than 2 – 10nm, depending on x, growth temperature, and substrate surface preparation. The strength of the broad PL band was correlated with the areal density of strain perturbations (∼109cm−2 per quantum well; local lattice dilation ∼1.5 nm in diameter) observed in plan-view TEM. The role of MBE growth parameters in determining optical properties was investigated by changing growth temperature, substrate preparation procedures and exploring the effect of surface passivation in a hydrogen ambient. In addition, post growth anneals at temperatures in the range 700°C to 1 100°C were carried out, where interdiffusion removes interfacial asperities and the broad luminescence band decays to zero intensity.
The Effects of Composition on the Spectral Loss Characteristics of SiGe Planar Waveguide Structures
Authors: Zuoya Yang , Weiss B. L. , Shao G. , Namavar F. 
Published: March 2011

ABSTRACTThe effect of the Si:Ge ratio in SiGe/Si heterostructures on the structural and optical properties of SiGe/Si planar waveguide are reported here for Ge concentrations from 1 to 33.6%. The high propagation loss at 1.15 pm is due to band edge absorption, which increases as the Ge concentration increases, while the loss at longer wavelengths (1.523 pm) increases with decreasing Si concentration, due to the reduced optical confinement of the waveguide structure.
Atomic Oxidation of Ultra Thin SiGe Using Afterglow Oxygen Plasma
Authors: Chen P. C. , Lin J. Y. , Hsut Y. J. , Hwang H. L. 
Published: March 2011

ABSTRACTMicrowave remote plasma oxidation system was used to study the oxidation of SiGe samples at low temperatures. The extent of Ge segregation at oxide/SiGe interface was investigated by using SIMS depth profiles. By comparing the segregation factors, the Ge segregation in the samples oxidized by atomic oxygen at 500 °C was much less than that in the samples oxidized without plasma at 950 °C. The Ge segregation has been largely suppressed by atomic oxygen oxidation at lower temperature.
Use of Valved, Solid Group V Sources for the Growth of GaAs/GaInP Heterostructures by Molecular Beam Epitaxy
Authors: Johnson F. G. , Wicks G. W. , Viturro R. E. , Laforce R. 
Published: March 2011

ABSTRACTWe report on the first growth of GaAs/Ga0.5In0.5P heterostructures by conventional molecular beam epitaxy using solid-source valved crackers to supply both the arsenic and the phosphorus fluxes. By regulating the group V fluxes with the cracker needle valves, arsenide-phosphide heterostructures were successfully grown with virtually no group V intermixing between layers. For comparison, similar heterostructure samples were grown using only the mechanical shutters to switch between group V fluxes, and the resulting layers were severely intermixed. The amount of group V intermixing was shown to be independent of whether As2 or As4 fluxes were used to grow the layers. A GaAs/Ga0.5In0.5P multiple quantum well sample was also grown using the valved crackers. Photoluminescence peaks were clearly observed from 40 Å, 80 Å, and 300 Å GaAs quantum wells, but no luminescence was detected from a 20 Å well. An 80Å GaAs/ 80Å Ga0.5In0.5P superlattice was grown, and superlattice satellite peaks were observed in the X-ray rocking curves. The appearance of misfit dislocations suggests localized intermixing at the interfaces.
Production of GexSi1−x, and SiC Films on Si Substrates Using Particle-Beam Technologies
Authors: Kagadey V. A. , Ladizhensky O. B. , Lebedeva N. I. , Matin E. N. , Proskurovsky D. I. , Yakovleva L. V. , Zaporozhchenko V. I. 
Published: March 2011

ABSTRACTThe paper presents the results of preliminary experiments on the production of GexSi1−x/Si structures using deposition of a thin Ge film on a Si substrate, implantation of Si ions and rapid electron-beam annealing. The conditions under which monocrystalline layers form have been found. It is supposed that the large depth of Ge penetration into Si is due to enhanced diffusion of Ge conditioned by the high density of point defects in the doped Si. It has been established that high-dose implantation of C ions into Si and subsequent electron beam annealing result in the formation of a monocrystalline layer of the SiC phase in the case of pulsed (∼0.7 μs) heating and liquid-phase recrystallisation and a polycrystalline SiC layer in the case of prolonged annealing.
Fabrication Process of Porous Silicon-Based Optoelectronic Devices
Authors: Kalkhoran Nader M. 
Published: March 2011

ABSTRACTA patterning process compatible with conventional Si electronics technology, which has resolution better than 5 μm, has been developed in order to perform selected-area anodic etching for producing luminescent porous Si layers (PSL). Correlations between the anodic etching and photolithographic parameters have been identified, and their effects on the resolution and luminescence of porous Si layers have been studied. Finally, the first monolithic processing, i.e.,. true wafer-scale integration, of a Si-based visible light-emitting diode (LED) and a photodetector using conventional Si technology has been demonstrated.
VUV- and Soft X-Ray-Induced Optical Luminescence and X-Ray Absorption Fine Structures of Porous Silicon
Authors: Sham T. K. , Jiang D. T. , Coulthard I. , Lorimer J. W. , Feng X. H. , Tan K. H. , Frigo S. P. , Rosenberg R. A. , Houghton D. C. , Bryskiewicz B. 
Published: March 2011

ABSTRACTOptical luminescence in porous silicon induced by soft X-ray and vacuum UV excitation with energies in the vicinity of the Si K-edge (1838 eV) and the Si L-edge (99 eV) has been observed. The luminescence has been used, together with total electron yield, to record X-ray absorption fine structure (XAFS) in the near-edge region of both Si edges. The near- edge spectra recorded simultaneously with either luminescence or total electron yield were compared, and the implications of these measurements for the structure of porous silicon are discussed.
Blue II-VI laser Diodes and light Emitting Diodes
Authors: Gunshor R. L. , Nurmikko A. V. , Otsuka N. 
Published: March 2011

ABSTRACTThe use of a nitrogen rf plasma source for p-type ZnSe grown by MBE, has allowed a variety of pn junction based devices to be realized. The pn junctions have been combined with (Zn,Cd)Se quantum wells to implement semiconductor injection lasers, operating in the blue/green portion of the spectrum, which were reported by 3M and the Brown/Purdue group in the summer of 1991. In the past year the field has moved rapidly. In particular, we can now report CW operation at low temperatures as well as pulsed operation at room temperature (490nm) using a Zn(S,Se)-based device configuration. Laser power output per facet for some designs is above 300 mW, and threshold current densities are as low as 1000A/cm 2 at room temperature. Lasing was demonstrated from devices grown on both p and n-type GaAs substrates. X-ray rocking curves of theII-VI regions exhibit FWHM values below 20 arcsec for specific samples. Dislocation densities are less than 105 cm−2, below the threshold of TEM plan view imaging. The blue LEDs provide power outputs in excess of 100μW while exhibiting external quantum efficiencies of 0.1% at room temperature.
Blue Lasers Based on II-VI Semiconductor Heterostructures
Authors: Yu Z. , Ren J. , Lansari Y. , Gossett K. J. , Sneed B. , Bowers K. A. , Cook J. W. , Schetzina J. F. 
Published: March 2011

ABSTRACTProperties of blue laser diodes based on ZnSe-related II-VI semiconductor heterostructures are reported. At 77 K, continuous-wave (cw) operation has been achieved for lasers emitting at wavelengths as short as 470.4 nm (2.635 eV), while pulsed laser emission has been observed up to ∼200 K, for samples with uncoated facets. Measured turn-on voltages for stimulated emission at 77 K were as low as 12 V for some of the laser diodes due to improved ohmic contacts. For some particular devices, differential quantum efficiencies as high as 36% per (uncoated) facet have been obtained at 77 K.
“On the Growth - and Annealing - Temperature Dependence of the Electrical Properties of Ga0.51In0.49P/GaAs Heterostructures Grown by Mombe”
Authors: Paloura E. C. , Ginoudi A. , Frangis N. , Christou A. 
Published: March 2011

ABSTRACTWe study the effect of growth temperature (TG) and post-growth rapid thermal annealing (RTA) on the electrical properties of Schottky diodes fabricated on undoped, lattice-matched Ga0.51In0.49P/GaAs heterostructures. The samples were grown by metalorganic molecular beam epitaxy (MOMBE) in the temperature range 480 – 560°C. Ga0.51In0.49P grown in this temperature range undergoes spinodal decomposition, as shown by cross-section TEM analysis. The dislocation-free epilayers grown at TG≤520°C are characterized by a deep electron trap with an activation energy of 800meV while growth at higher temperatures renders trap-free films. Furthermore, the Schottky barrier ideality factor (n) depends strongly on TG and takes the best value of 1.4 for TG=540°C, while the barrier height remains nearly constant at about 0.75eV. Finally, upon capped rapid thermal annealing the value of n improves while the trap concentration decreases significantly. Based on the presented experimental evidence we can propose that MOMBE growth at 540°C renders films with improved electrical properties.