bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid Thermal Annealing of GaAs/AlGaAs Coupled Double Quantum Wells
Authors: Koteles Emil S. , Elman B. , Armiento C. A. , Melman P. , Chi J. Y. , Holmstrom R. J. , Powers J. , Owens D. , Charbonneau S. , Thewalt M. L. W. 
Published: March 2011

ABSTRACTThe effect of rapid thermal annealing (RTA) on the shapes of silicon dioxide capped symmetric coupled double GaAs/AlGaAs quantum wells (CDQW) has been investigated. In contrast to previous results on single quantum wells in which increases in exciton energies were observed after RTA, large decreases in exciton energies were seen in CDQWs. Furthermore, there was clear evidence, in the excitation spectrum and in increases in the lowest energy exciton lifetime, of asymmetry present in the heterostructure after RTA.
Local Atomic Interdiffusion in CdTe/HgCdTe Multilayered Structures
Authors: Kim Y. , Ourmazd A. , Feldman R. D. , Rentschler J. A. , Taylor D. W. , Austin R. F. 
Published: March 2011

ABSTRACTWe combine chemical lattice imaging with digital pattern recognition to study atomic interdiffusion at individual CdTe/HgCdTe interfaces in multi-quantum well structures. In this way we obtain quantitative composition profiles for “as grown” samples, and investigate their development as a function of annealing temperature. Our results indicate that interdiffusion depends on the position of the quantum well with respect to the surface, beginning first at quantum wells close to the surface, and proceeding towards the substrate. Our approach allows the quantification of interdiffusion as a function of time, temperature, and distance from the surface. The implications of these results for the stability of CdTe/HgCdTe structures, and the interpretation of X-ray data are discussed.
Phase Separation and Atomic Ordering in Epitaxial Layers of III-V Compound Semiconductors
Authors: Mahajan S. , Shahid M. A. 
Published: March 2011

ABSTRACTMIcrostructural characteristics of phase separated and ordered ternary and quaternary layers of Ill-V compound semiconductors grown by a variety of techniques are highlighted. It is argued that the fine scale contrast modulations seen in a number of layers arise from a two-dimensional, surface spinodal decomposition at the growth temperature. On the other hand, coarse contrast modulations could result from accommodation of asymmetrical strains associated with the twodimensional decomposition.Long range atomic order is observed in a variety of layers grown by different techniques and co-exists with phase separation. In InGaAs and InGaAsP layers, grown on (001) InP substrates, ordering is observed only on the two {111} planes that contain the line of intersection of the {111}in plane with the (001) InP surface. As a result of ordering, periodicity along the 〈111〉 direction is doubled. Also, the influence of growth temperatures and growth rates on ordering characteristics in GalnP and (Ga, Al) InP layers is reported.
Inversion Domain Boundary Dislocations in Heteroepitaxial Films
Authors: Cheng T. T. , Pirouz P. , Ernst F. 
Published: March 2011

ABSTRACTTransmission electron microscope (TEM) images of inversion domain boundaries (IDB) show fringe contrast, thus indicating a relative displacement between the two adjoining domains. When the IDBs are facetted, different facets may have different displacement fault vectors. This implies that when the facetting changes from one plane to another, there should be a dislocation at the intersection of the planes. This is termed an “inversion domain boundary dislocation” and it will have a Burgers vector b=R1–R2 where R1, and R2 are the fault vectors of the two facets. Experimental results for facetted IDBs and IDB dislocations in SiC grown heteroepitaxially on (001) silicon are presented.
I-V, C-V, and Hall Effect Studies of Indium-Doped Lpe GaAs
Authors: Chen J.F. , Xie K. , Wie C.R. 
Published: March 2011

ABSTRACTWe have studied the effects of In doping on the electrical properties of a liquid phase epitaxially (LPE) grown GaAs. The I–V characteristics of Au-GaAs Schottky diodes show, for the layer with In concentration of 2.4 × 1019 cm−3, an ideality factor close to 1.04 over more than seven decades of current. For the same sample, the reverse I–V characteristics are close to an ideal Schottky diode and can be fitted by a theoretical curve, combining the thermionic field emission and thermionic emission. The electrical improvement is closely related to the low etch pit density and other structural improvements. This indicates that, as in the LEC growth, In has effects on the reduction of disloation density in the LPE grown GaAs epi-layer. For doping levels higher than 6×1019 cm−3, an excess forward current is produced at low voltages and low temperatures. A large leakage current is observed under the reverse bias. This property is attributed to a high field effect, with field emission via a trap state as the most likely cause. Hall measurements showed that the ratio of free-carrier concentration ND−NA to the total-carrier concentration ND+NA increased with increasing In concentration.
GaAs on Si Grown by Mbe: Progress and Applications for Selectivity Doped Heterojunction Transistors (SDHTs)
Authors: Chand Naresh , Van Der Ziel J. P. , Weiner J. S. , Sergent A. M. , Lang D. V. 
Published: March 2011

ABSTRACTRecent progress of GaAs-on-Si technology is reviewed and the importance of initial nucleation is emphasized. Growth initiation with a Ga prelayer at a suitable low temperature combined with migration enhanced epitaxy and in-situ thermal annealing has a prospect of giving substantially improved material quality. During the initial growth, use of the minimum necessary As4/Ga flux ratio is found to be critical. The random alignment of the major axis of the oval defects is suggested to be an alternative simple technique to detect the presence of antiphase domains. Patterned growth or post growth patterning releases tensile stress only if the growth edges are free. GaAs-on-Si was completely relaxed from stress by post-growth patterning to 5 μm × 5 μm size patterns. Steps on the surface due to substrate misorientation do not affect the two dimensional electron gas (2DEG) transport properties in AlGaAs/GaAs selectively doped heterojunction transistor (SDHT) structures. For a sheet density of 1012 cm−2, the 2DEG mobility >50,000 cm2V−1s−1 at 77 K was obtained on Si substrates, which is sufficient for fabrication of high performance SDHTs. The study shows that GaAs-on-Si has a great potential for SDHT technology.
Formation of High Quality GaAs/Si Hetero-Structure by Solid Phase Epitaxy
Authors: Miyao M. , Shimada T. , Nishid A. , Inada T. , Tamura M. , Ishino M. , ohbu I. 
Published: March 2011

ABSTRACTImprovements of crystal quality in GaAs/Si heterostructure by solid phase epitaxy (SPE) are described. RBS and TEM measurements indicate that high density defects are located near the GaAs/Si interface after “2-step MBE”. Utilization of post SPE process (amorphization plus regrowth) significantly improve crystal qujali ty at the GaAs/Si interface, although a small stress field is introduced. In addition a new relation between photoluminecence intensity ratio and stress field is established. This provides a useful too] for measuring small stresses remaining in the GaAs/Si hetero-structure.
Thermal Annealing Effects in the Strained (Ga, In) as Layer
Authors: Choi Y-W. , Kim H.M. , Rajeswaran G. , Wie R. 
Published: March 2011

ABSTRACTWe have studied the ternary (Ga, In)As layers in GaInAs/GaAs heterostructure systems after conventional furnace annealing or rapid thermal annealing (RTA). Measurement was done by the double crystal X-ray rocking curve technique (XRC) and the Auger Electron Spectroscopy technique (AES). X-ray rocking curves show an asymmetric shoulder in the GaInAs epilayer peak indicating a smaller lattice spacing near the surface. Epilayer peaks of encapsulated samples also show an asymmetric shoulder which is perhaps due to the tensile stress in the epilayer caused by the encapsulant film. AES depth profiles for 600°C, 15 minutes proximity annealed sample show that the concentrations of Ga, In, and As are not uniform over about 60 nm depth, showing a Garich and In, As-deficient surface. For 700°C, 20 seconds a RTA treated sample shows no such non-uniformity.
The Influence of the Arsine Source on the Purity of InGaAs Grown by Hydride VPE
Authors: Noel Buckley D. , Matthiesen M. M. 
Published: March 2011

ABSTRACTThe relatively high background carrier concentration obtained in unintentionally doped epitaxial layers of III-V materials imposes a limitation on applications of the hydride VPE process. It is usually attributed to impurities in the gas sources. Results are presented for InGaAs grown by hydride VPE using a range of growth conditions. Carrier concentrations and growth rates for the various samples were determined using, respectively, Polaron electrochemical profiler measurements and scanning electron microscopy. It is shown that the observed background carrier concentration increased with increasing input mole fraction of arsine under conditions of constant growth rate. This strongly implicates the arsine feed gas as a predominant source of impurity. Attempts to purify the arsine feed gas using sodium alumina-silicate molecular sieves are described. Polaron electrochemical profiler measurements and Hall effect measurements on samples grown both with and without molecular sieves in the arsine feed line are presented. From a comparison of the corresponding values of carrier concentration and mobility it is shown that Type 4A molecular sieves were not effective in removing dopant impurities from the 4% arsine-hydrogen mixture used.
Ion Implantation and Characterization of III-V Materials
Authors: Wilson R. G. , Rensch D. B. 
Published: March 2011

ABSTRACTWe have implanted most dopant elements into GaAs, GaP, InP, and InSb, to energies from 10 to 700 keV, and a few up to 2.4 MeV, in random and channeled orientation, annealed some of these implants, and measured the depth distributions using secondary ion mass spectrometry (SIMS) . We have calculated values of Rm, Rp, ΔRp, γ1, β2, using an LSS formulation, and measured these same profile parameters for the experimental profiles using a Pearson IV computer fitting routine. We describe a study of the fabrication of self-aligned W-gate FETs in GaAs using Si-implanted channels and source/drains, and a buried p implant (Be or Mg) to compensate the backside (tail) of the Si profile. The implant profiles and electrical device characteristics, including the effects on AVt of various implant conditions, are discussed.
Ion Implantation Damage and its Annealing Characteristics in an AlAs/GaAs Layer Structure
Authors: Cullis A. G. , Jacobson D. C. , Poate J. M. , Chew N. G. , Whitehouse C. R. , Pearton S. J. 
Published: March 2011

ABSTRACTThe implantation of Ar+ ions into AlAs/GaAs layered samples is shown to give very different damage structures in the two materials. While the GaAs is relatively easily amorphised, the AlAs is quite resistant to damage accumulation and remains crystalline for the ion doses employed in these investigations. The behaviour of the different damage structures when subjected to rapid thermal annealing treatments is described in some detail. It is demonstrated that differences in the initial damage state have a strong influence upon the nature of lattice defects produced by annealing.
Some Applications of Ion Beams in III-V Compound Semiconductor Device Fabrication
Authors: Donnelly J. P. , Anderson K. K. , Woodhouse J. D. , Goodhue W. D. , Yap D. , Gaidis M. C. , Wang C. A. 
Published: March 2011

ABSTRACTIon-beam-assisted etching of GaAs/AlGaAs and InP/GaInAsP, ion-beam disordering of GaAs/AlGaAs multiple-quantum-well structures, and ion implantation in InP are discussed.
Mg+ Ion Implantation into GaAs : Annealing and Photoluminescence Properties
Authors: Takeuci Yoshinori , Makita Yunosuke , Mori Masahiko , Ohnishi Nobukazu , Shibata Hajime , Matsumori Tokue 
Published: March 2011

ABSTRACTMg ion-implantation was carried out into very pure GaAs made by molecular beam epitaxy, in which the dose of Mg atoms, [Mg] was varied from l×1015 to 1×1020 cm−3 . As a method of characterization, low temperature photoluminescence (PL) studies were carried out as a function of [Mg]. A new emission, denoted by [g-g] was observed between bound exciton emissions and the emission due to 1 and-to-acceptor pairs. It was found that [g-g] appears around [Mg]= 2×1016 cm−3 and becomes a dominant emission at [Mg] over l×1017 cm−3. A significant shift of [g-g] towards the lower energy side with increasing [Mg] was reproducibly obtained and its PL properties were carefully investigated in terms of annealing temperature, TA and excitation density. Results revealed that the implanted Mg atoms become optically active at TA over 600 [g-g] was suggested to be acceptor-acceptor pair, which is consistent with the theoretical explanation that its radiative mechanisms is ascribed to the pair between excited-state acceptors. The systematic energy shift inherent to [g-g] was attributed to the growing ionization energy of the pair with increasing pair distance.
Electrical Activation Behavior of Ion Implanted Silicon in Gallium Arsenide During Rapid Thermal Annealing
Authors: de Souza J.P. , Sadana D.K. , Hovel H.J. 
Published: March 2011

ABSTRACTRapid thermal annealing (RTA) (800–1000°C, 1–60 s) was performed on capless and silicon nitride (SixNy) capped GaAs samples implanted with Si (30 keV, 4.5×1013cm−2 ) and SiF+ (50 keV, 4.5×1013cm−2 ). The maximum activation for the Si+ implants saturated at 25% (capless) and 42% (capped) and that for the SiF+ implants saturated at 20% (capless) and 35% (capped). The activation degraded at temperatures > 825°C due to surface decomposition in the capless annealing case and at > 925°C due to the cap failure in the capped annealing case. For all the RTA conditions studied here, higher activation always occurred with the Si+ rather SiF+ implants. An activation energy of 0.48 eV for the annealing process was determined from the electrical data. It was also observed that the heating and/or cooling rates can significantly influence the electrical activation.
Evolution of the GaAs(001) Surface Physico-Chemical Characteristics and Electrical Properties of the Si3N4/GaAs Interface with the NH3Photolysis Treatment of the GaAs Surface.
Authors: Guizot J.L. , Alnot P. , Perrin J. , Allain B. 
Published: March 2011

ABSTRACTCleaning treatments of GaAs(001) by UV decomposition of NH3 has been studied by means of X-ray photoemission spectroscopy (XPS) and X-ray photoelectron diffraction (XPD). This photolysis treatment is shown to decompose the surperficial oxides and to remove the carbon of contamination. The surface cleaning is followed by the formation of gallium nitride overlayers. When used prior to UVCVD silicon nitride deposition, this treatment is shown to improve the electrical characteristics of the Si3N4/GaAs MIS structure.
Downstream Plasma Activated Etching of IIIV Compound Semiconductorsa
Authors: Iyer R. , Lile D.L. 
Published: March 2011

ABSTRACTWe have demonstrated a novel downstream plasma activated vapor phase etching of III-V compound semiconductors using ethylene di bromide as the etchant. Highly reproducible surfaces and etch rates were obtained by monitoring the reaction process with a mass spectrometer. Etch rates on InP of up to 4500Å/min, at temperatures as low as 160°C, at an rf power input of 25 watts were achieved with no evident damage to the surface as indicated by PL measurements. Apparent activation energy measurements seem to suggest that the etch products might be organometallic in nature, in contrast to inorganic etch products seen in most etching studies. Etching is partially anisotropic and resulted in smoother surfaces when H2 was used as the carrier gas for the etchant instead of N2.
Thin-Film Encapsulants for Thermal Processing of GaAs
Authors: Molarius J.M. , Kolawa E. , Morishitaal K. , Pan E.T-S. , Tandon J.L. , Nicolet M-A. 
Published: March 2011

ABSTRACTDuring heat treatment of GaAs there is a tendency for arsenic to evaporate. This process can have deleterious consequences and must be controlled during the annealing of GaAs by using encapsulants. In this work we use a Cr collector to catch the evaporated atoms. This collector is placed on top of GaAs or GaAs/cap during annealing. We survey the effectiveness of W, Hf and HfN as capping materials for thermal annealings of 10 min. for 450–700 C and compare them to Si3N4. The backscattering spectrometry results show that Si3N4 and W were excellent caps up to 700 C for 10 min. No evaporation was defected through HfN either, but hillock formation was detected on the surface. Hf failed because of its chemical reaction with GaAs at 650 C, 10 min.
A Comparative Study of Te- and Ge-Based OHMIC Contacts on GaAs
Authors: Wuyts K. , Vantomme A. , Silverans R.E. , Van Hove M. , Van Rossj M. 
Published: March 2011

ABSTRACTThe formation of furnace processed Te- and Ge-based ohmic contacts on n-GaAs was investigated using Rutherford Backscattering Spectroscopy and electrical measurements. Contact resistivities obtained with the Ni/Au/Te metallization were comparable to those of the standard Ni/AuGe scheme, the lowest value for both metallizations being 5.10−6Qcm2. The onset of ohmicity of the Au/Te scheme varied from 480°C to 550°C by changing the Au/Te thickness ratio. The diffusion characteristics of the contacting metals were studied on GaAs as well as on SiO2 substrates. Arguments in favor of the model explaining the nature of the contacts by the formation of a heterojunction-like structure are adduced.
Organometallic Vapor Phase Epitaxial Growth of ZnGeAs2 and (ZnGeAs2)xGe1−x on GaAs
Authors: Solomon G. S. , Posthill J. B. , Timmons M. L. 
Published: March 2011

ABSTRACTEpitaxial single crystal (001) chalcopyrite-structure ZnGeAs2 and single crystal (100) zinc blende-structure (ZnGeAs2)xGe1−x alloys have been grown by organometallic vapor phase epitaxy on (100) GaAs. Selected area electron diffraction was used to determine the crystal structure for several Zn:Ge molar flow ratios. Bulk chemical composition was determined by electron microprobe and correlated to crystal lattice constants obtained from x-ray diffraction. Due to the lattice mismatch between chalcopyrite-structure ZnGeAs2 and the GaAs substrate, the epitaxy is elastically strained, compressing the a-lattice constant and elongating the c-lattice constant. Optical absorption and transmission spectroscopy indicate the zinc-blende-structure material has an indirect band gap of approximately 0.6 eV, whereas the chalcopyrite ZnGeAs2 has a direct band gap of 1.15 eV. Secondary ion mass spectroscopy reveals significant Zn diffusion into the GaAs substrate if the Zn:Ge molar flow ratio exceeds the ratio required for stoichiometric chalcopyrite-structure crystal growth.
Measurement of Mobility Profile in GaAs MESFET's by Schottky Barrier Technique with Gate Current Correction
Authors: Qi Xiang , Lichun Wang , Jinsheng Luo 
Published: March 2011

ABSTRACTThe mobility profile of electrons in active layer of GaAs MESFET has an inportant effect on the device performance. The mobilities at layers of different depth can be measured by changing the negative gate bias, but the electron mobility near the surface can't be measured yet due to the depletion of electrons in the surface layer. This paper introduces a differential d.c. equivalent model, in which the Schottky barrier can be forward biased and the gate current correction is properly included. Applying this model, we can precisely calculate the drift and gecmetrical magnetic resistance mobilities very close to the surface layer.
Sheet Density and Well Thickness Effects on Photoluminescence from Pseudomorphic HEMT Structures
Authors: Colvard C. , Nouri N. , Lee H. , Ackley D. 
Published: March 2011

ABSTRACTLow temperature photoluminescence was studied in a large number of pseudomorphic HEMT's having an InxGa1−xAs quantum well. The spectra show strong qualitative differences when the Fermi level is above or below the second conduction subband, and in the latter case they are power dependent. A slight enhancement is seen at the Fermi edge only when it lies close to the higher subband. Excellent agreement is found between the measured Fermi energy and the two-dimensional carrier density in the well.
A Mathematical Model of the Gas-Phase and Surface Chemistry in GaAs Mocvd
Authors: Coltrin Michael E. , Kee Robert J. 
Published: March 2011

AbstractThis paper presents a detailed mathematical model of the coupled gas-phase chem- istry, surface chemistry, and fluid mechanics in the MOCVD of GaAs from trimethylgallium and arsine in a rotating-disk reactor. The model predicts steady-state deposition rates as a function of susceptor temperature and partial pressure of the reactants. Rate constants in the model have been adjusted to match experimental deposition rates from the literature.
Highly Strained InAsxPl-X/InP Quantum wells Prepared by Flow Modulation Epitaxy
Authors: Schneider R. P. , Wessels B. W. 
Published: March 2011

AbstractFlow modulation techniques have been used to prepare highly strained InAsxPl-x/InP quantum well structures in an atmospheric pressure organometallic vapor phase epitaxial reactor. The compositions of the pseudomorphic wells ranged from x=0.40 to 0.74, corresponding to biaxial compressive strains of 1.3-2.4%. Well thicknesses ranged from 2 to 26 monolayers. The flow modulation growth conditions were found to have a strong influence on interface formation in the wells. For wells grown under optimized modulation conditions, low-temperature photoluminescence spectra revealed peak-splitting of the emission from the thinnest wells. This splitting is attributed to emission from regions in the wells with atomically smooth interfaces over areas greater in lateral extent than the exciton diameter. The full-width at half-maximum of the peaks is in the 6-15 meV range, comparable to the best reported values for lattice- matched InGaAs(P)/InP quantum wells grown by any technique, and is independent of well thickness or composition.
The Role of Arsine in Reducing Carbon in Triethylarsenic Grown GaAs Films
Authors: Speckman D.M. , Wendt J.P. 
Published: March 2011

AbstractVery high carbon impurity levels (1018-1021cm−3) in GaAs films grown using triethylarsenic (Et3As) and trimethylgallium (Me3Ga) can be dramatically reduced by substituting a portion of the Et3As reagent with arsine during growth. Gallium arsenide epilayers grown at a deposition temperature of 560°C, a total V/III ratio =10, and the Group V reagent consisting of a mixture of Et3As and arsine, were found to exhibit carbon levels of only 5-7×1015cm−3for Group V mixtures ranging from 0-65% Et3As. All of these films were n-type, except for those grown using 100% arsine, which were p-type. The reduction in carbon incorporation in films grown using Et3As and arsine as co-reagents is shown to result from a unique, synergistic, reaction chemistry involving the two arsenic reagents. In particular, the decomposition of arsine to provide carbon-free, active arsenic fragments for growth is greatly enhanced by the presence of Et3As as a co-reactant.
Metalorganic Chemical Vapor Deposition of High Quality GaAs and AlGaAs Using Tertiarybutylarsine
Authors: Haacke G. , Watkins S. P. , Burkhard H. , Calbick C. J. , Quick J. 
Published: March 2011

AbstractThis paper discusses recent improvements achieved in the growth of epitaxial layers of GaAs and AlGaAs using the liquid arsine substitute tertiarybutylarsine (TBA) and metal alkyls. The high purity TBA now available yields undoped GaAs with residual donor/acceptor concentrations in the low 1014 cm−3 range. Under optimized growth conditiorp the layers are either n-type and have 77*K mobilities up to 85,000 cm2 //Vs or they are compensated or p-type. For aluminum gallium arsenide, layers grown with TBA have properties similar to arsine-grown material as demonstrated by low temperature photoluminescence (PL). The PL efficiencies and line widths of the TBA-grown AlGaAs samples are comparable to those prepared with arsine.