bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fundamental Issues in Heteroepitaxy (Condensed from the Doe Panel Report)
Authors: Peercy P. S. 
Published: March 2011

AbstractThe Department of Energy’s Council on Materials Science convened a Panel charged with assessing the present scientific understanding of epitaxial growth and identifying fruitful research opportunities in this area. The Panel, chaired by Paul S. Peercy, a member of the Department of Energy’s Council on Materials Science and of the Solid State Sciences Committee, was composed of scientists in materials science, physics, and chemistry from academia, government labs and industry. Panel members were: Ernst G. Bauer, Brian W. Dodson, Daniel J. Ehrlich, Leonard C. Feldman, C. Peter Flynn, Michael W. Geis, James P. Harbison, Richard J. Matyi, Pierre M. Petroff, Paul S. Peercy, Julia M. Phillips, Gerald B. Stringfellow and Andrew Zangwill. The Panel met in January, 1989; its activities were supported by the Materials Sciences Division of Basic Energy Sciences. Deliberations emphasized artificially structured materials and resulted in a Panel Report which has been submitted to the Journal of Materials Research. With permission from the Department of Energy, this article excerpts from the report.
Ge Transport and Epitaxy on [111] Si in the Ge/Pd2Si/Si System
Authors: Hong Q. Z. , Zhu J. G. , Xia W. , Mayer J. W. 
Published: March 2011

AbstractSolid phase epitaxy in the amorphous(a)-Ge/Pd2Si/Si system has been investigated in the temperature range of 600 to 750 °C. The top Ge started to migrate into the suicide layer at 600 °C. After longer time annealing the mixed Ge released from the suicide matrix and formed a laterally uniform epitaxial Ge70Si30 layer on the [111] Si substrate. A minimum yield of 0.1 was achieved for a 800 Å-thick Ge70Ge30 layer.
Characterization of ErAs/GaAs and GaAs/ErAs/GaAs Structures
Authors: Zhu Jane G. , Palmstrøm Chris J. , Mounier Suzanne , Barry Carter C. 
Published: March 2011

AbstractA series of ErAs/GaAs and GaAs/ErAs/GaAs epilayers have been grown on (100) GaAs substrates by molecular-beam epitaxy. Misfit dislocations at the ErAs/GaAs interface have been analyzed using the weak-beam technique of transmission electron microscopy. The microstructure of GaAs/ErAs/GaAs layers have been characterized using conventional and high-resolution electron microscopy. Twinning inside the upper GaAs layer is the major defect. Although the desired epitactic (100) GaAs on (100) ErAs does dominate, small grains of GaAs with (111) or {122} orientations have been observed at the GaAs/ErAs heterojunction.
Epitaxial growth of Matched Metallic ErP0.6 As0.4 layers on GaAs
Authors: Guivarc'h A. , Le Corre A. , Caulet J. , Guenais B. , Minier M. , Ropars G. , Badoz P.A. , Duboz J.Y. 
Published: March 2011

AbstractSuccessful growth of (001 )ErP0.6As0.4 single crystal film on (001) GaAs has been demonstrated. The epitaxial metallic layers reproducibly showed lattice mismatch below 5 10-4. This is, to our knowledge, the first report of a stable, epitaxial and lattice-matched metal/compound semiconductor heterostructure. The ErP0.6As0.4/n-GaAs diodes yielded excellent I-V characteristics with an ideality factor of 1.1 and barrier height of 0.88 eV. For a 240 A-thick film, metallic behavior was observed with resistivities of 25 and 86 µΩcm at 1.5 K and room temperature, respectively. As the other Er compounds ErP, ErAs, ErSb and ErSi2, ErP0.6As0.4 presents an abrupt drop in resistivity in the vicinity of the liquid helium temperature, due to a paramagnetic to antiferromagnetic phase transition.
Strained InGaAs/GaAs quantum wells with a 1.3 µm bandedge at room temperature
Authors: Melman P. , Elman B. , Jagannath C. , Koteles Emil S. , Silletti A. 
Published: March 2011

AbstractThe fabrication of long wavelength opto-electronic devices on GaAs substrates is an attractive method for the monolithic integration of optical and electronic devices on a single chip for applications in telecommunications. InGaAs strained layer quantum wells provide one way of engineering the bandgap needed for 1.3 µm devices at room temperature. We have grown and characterized quantum well structures with bandgap of .96 eV using a novel technique, called spatial strain separation, to avoid the stringent limitation of critical thickness which limits the achievable bandgap in this material system. Moreover we have studied the stability of such structures with respect to thermal processing, including oven and rapid thermal annealing. We have observed no degradation of the quantum wells after thermal annealing as judged from the PL spectra shown here.
Pulsed Laser Atom Probe Analysis of III-V Compound Semiconductor Epilayers.
Authors: Mackenzie Ross A. D. , Alex Liddle J. , Grovenor Chris R. M. , Cerezo Alfred 
Published: March 2011

AbstractThe pulsed laser atom probe has been used to characterise the fine scale chemistry of a range of III-V ternary and quaternary compound semiconductors (GaInAs, AlInAs, GaAlInAs) grown, using MOCVD techniques, on indium phosphide substrates. It has been observed that there are fine scale chemical fluctuations in some specimens on a scale of typically 10–20 nm. The fluctuations appear to be a result of localized clustering of the group III components in the epilayer. In quaternary material there is evidence for different degrees of clustering for different components. It is suggested that this compositional fluctuation is a consequence of clustering occuring above a miscibility gap. The existence of a TEM contrast mechanism inherent to the material has the effect of making TEM an unreliable indicator of fine scale compositional variations in these systems.
Electrical Properties of Mesa Diodes on Epitaxial GaAs/Si
Authors: Jiao K.L. , Soltyka A.J. , Anderson W.A. , Vernon S.M. 
Published: March 2011

AbstractDeep level transient spectroscopy (DLTS), current-voltage- temperature (I-V-T), capacitance-voltage-temperature (C-V-T), C-T and photoreflectance spectroscopy (PRS) were used to compare the electrical properties of GaAs p-n junctions epitaxially grown by MOCVD on GaAs and Si substrates. EL2 was detected for both GaAs/GaAs and GaAs/Si structures. For GaAs/Si, a continuous distribution of trap levels was also observed which could be ascribed to misfit defects. I-V-T data revealed the saturation current of GaAs/Si diodes to be four orders in amplitude higher than for GaAs/GaAs ones. Different temperature dependences were found in saturation current density, barrier height and capacitance between the two structures. A multistep tunneling model is utilized in explaining the results for GaAs/Si. C-T measurements indicated the free carriers not to be frozen-out for GaAs/Si at the freeze-out temperature of GaAs/GaAs. A defect- induced bandgap tailing effect might be responsible for this effect, verified by PRS tests.
Metastable Electronic Effects in Amorphous Semiconductor Superlattices
Authors: Kakalios J. 
Published: March 2011

AbstractThis paper reviews some of the novel electronic effects observed in amorphous semiconductor superlattices. Quantum size effects have been reported in compositionally modulated amorphous semiconductors based upon optical absorption and tunneling studies. However, the quantum well effects are in direct conflict with transport data estimates of the inelastic scattering length. In doping modulated amorphous semiconductors, a large persistent photoconductivity PPC is observed, which cannot be explained by the field separation model alone, but rather requires the presence of a defect which undergoes a large lattice relaxation upon trapping a charge (similar to the DX center). Studies of npnp amorphous silicon multilayers have enabled a microscopic determination of the process responsible for PPC.
Structural Properties and Thermal Evolution of Fe/Ti Multilayers
Authors: Rodmacq B. , Hillairet J. , Laugier J. , Chamberod A. 
Published: March 2011

AbstractX-ray diffraction, electrical resistivity and dimensional variation measurements have been performed in order to characterise the structural and transport properties of Fe/Ti multilayers both in the as-prepared state and during thermal annealing. For small periods, the multilayers consist of hep Ti and amorphous iron-rich layers. Increasing the period leads to the crystallisation of the Fe-rich layers, which correlates with a sudden decrease of the electrical resistivity. Depending on the period (that is on the initial structure of the layers), very different types of evolution are observed upon annealing, corresponding to either interdiffusion or preferential diffusion of one of the species.
Magnetic Aftereffect in Compositionally-Modulated Ni/Cu Multilayers Prepared by Electrodeposition and by Sputtering
Authors: Bennett L.H. , Swartzendruber L.J. , Atzmony U. , Lashmore D.S. , Abdul-Razzaq W. 
Published: March 2011

AbstractA relaxation of the magnetization following a rapid change in the magnetic field has been found in a compositionally-modulated Ni/Cu multilayer produced by sputtering. This finding demonstrates that the relaxation previously found in compositionally-modulated alloys produced by electrodeposition is a property of the material and not an artifact of the electrodeposition process.
Characterization of Modulation Doped Pseudomorphic AlGaAs/InGaAs/GaAs Hemt Structures by Electron Beam Electroreflectance and Photoluminescence
Authors: Herman M. H. , Ward I. D. , Kopf R. F. , Pearton S. J. , Jones E. D. 
Published: March 2011

AbstractWe have investigated the optical transitions present in MBE-grown modulation doped pseudomorphic AlxGa1-xAs/InyGa1-yAs/ GaAs HEMT structures of 120Å InGaAs thickness, y values 0 to 0.28, and x values 0.20 to 0.30. From both 300K electron beam electroreflectance (EBER) and 4K photoluminescence (PL) measurements we observe transitions from the InGaAs strained quantum well layer. The intensity and lineshape of the InGaAs transition in both optical spectra are affected by processing temperatures, and provides an indication of the quality of the HEMT.In addition to strong, sharp features arising from the GaAs substrate and the superlattice buffer, the EBER data shows important characteristics of the AlGaAs layer which are unavailable from the PL. The latter include the presence of Franz-Keldysh oscillations, from which the crystal quality, composition, and electric field strength within the AlGaAs can be assessed. Specifically, when the growth temperatures are excessive, the disappearance of the Franz-Keldysh oscillations appears to be associated with outdiffusion of In from the strained layer, and consequent deterioration of active device performance.
Electric Field Effects on the Optical Properties of InxGa1-xAs/GaAs Strained Quantum Wells and Superlattices
Authors: Gibb K. , Lacelle C. , Roth A.P. , Soucail B. , Dupuis N. , Voisin P. , Hua B.Y. , Fortin E. 
Published: March 2011

AbstractWe have used photoluminescence excitation and photocurrent spectroscopy to investigate the electronic properties of InxGa1-xAs/GaAs strained layer quantum wells and superlattices. In quantum wells, sharp excitonic transitions between discrete energy levels are observed both in excitation and near flatband photocurrent spectra whereas superlattices show heavy-hole to conduction miniband transitions at the Brillouin mini-zone centre and edge, directly giving the electron miniband width. Applying a longitudinal electric field to the quantum wells produces a red shift of the excitons due to the quantum confined Stark effect, while in superlattices, photocurrent spectra at finite applied electric fields show for the first time in this system, the effects of Wannier-Stark quantization. The analysis of the spectra provides a precise determination of the band offset.
Hot-Carrier Effects on Optical Properties of GaAs/AlxGai1-xAs Quantum Wells
Authors: Chen W.M. , Holtz P.O. , Monemar B. , Sundaram M. , Merz J.L. , Gossard A.C. 
Published: March 2011

AbstractWe report on a study of hot-carrier effects on optical properties of GaAs/AlxGa1-xAs quantum wells, by photoluminescence (PL) spectroscopy in the presence of a microwave (MW) field. Both doped and undoped, multiple quantum wells (MQWs) and single quantum wells (SQWs), grown by molecular beam epitaxy (MBE), show a profound enhancement of free exciton (FE) and bound exciton (BE) (for the doped wells) PL emissions with MW irradiation. This is attributed to effects of hot-carriers induced by the MW electric field. The mechanism responsible for the strong enhancement in PL intensity of the QWs in the presence of hot-carriers is studied, and is discussed in terms of an enhanced carrier trapping by the QWs as a consequence of the MW-induced heating of the photo-excited free carriers in the AlxGa1-xAs barriers.
Anisotropic Transport in InGaAs/GaAs Heterostructures Grown by Movpe
Authors: Sun Qing , Morris D. , Lacelle C. , Roth A.P. 
Published: March 2011

AbstractAnisotropic electron transport has been observed in InxGa1-xAs/GaAs heterostructures grown by MOVPE on (001) and intentionally misoriented GaAs substrates. The low field electron mobilities in two perpendicular directions are found to be higher in the [110] direction than in the [110] direction. The ratio of µ[110]/µ[110] derived from Hall measurements is related to the degree of substrate misorientation as well as epilayer composition. Finally, the photoluminescence spectra are polarized along orthogonal <110> directions. These anisotropic properties are directly related to the anisotropy of [110] and [110] dislocations due to lattice mismatch between the substrates and the layers.
Application of GaAs-AlGaAs Superlattice Structure for Fabricating High Breakdown Voltage Power MISFET
Authors: Liu W.C. , Lour W.S. , Wang R.L. , Sun C.Y. , Hsu W.C. 
Published: March 2011

AbstractA new power MISFET with undoped GaAs-Al0.3Ga0.7As superlattice gate “insulator” and buffer structure has been fabricated successfully. The superlattice gate “insulator” exhibits a much higher gate breakdown voltage( >35V) with very low prebreakdown leakage current and a lower gate capacitance (C ). Due to the existence of gate “insulator”, a higher carrier concentration can be employed in the active channel which improves the output drain current capability and transconductance. If the gate length is reduced to 1 um, a higher transconductance up to 330 mS/mm can be expected.The insertion of superlattice buffer structure, between active channel and buffer layer offers an excellent carrier confinement barrier and gives an interface degraded region smaller than 40A. In addition, the superlattice buffer structure can getter greatly deep level impurities and defects from substrate or buffer layer. In summary, the proposed MISFET structure is suitable for high power, high frequency and low noise applications.
Theory and Experiment: Defect Stabilization of Diamond Films Through Multiple-Regrowth
Authors: Bar-Yam Y. , Moustakas T. D. 
Published: March 2011

ABSTRACTThe growth of diamond is now known to occur by chemical vapor deposition at low pressure even though diamond is thermodynamically unstable to graphite under these conditions. A new quasi-equilibrium theory is discussed which describes how the rapid multiple regrowth of layers with a large concentration of vacancies may stabilize nucleation and growth of diamond. Accurate theoretical calculations show that vacancies raise the energy of graphite more than diamond thus reversing the usual energy balance and leading to the growth of diamond films. One prediction of this theory is that electron rich conditions enhance both growth and nucleation. Experiments display the enhanced growth and nucleation. Raman measurements on diamond films also suggest the presence of a large concentration of defects in the resulting films.
Effect of Doping with Nitrogen and Boron on Cathodoluminescence of CVD-Diamond
Authors: Yokota Y. , Kawarada H. , Hiraki A. 
Published: March 2011

ABSTRACTWe have investigated cathodoluminescence (CL) of nitrogen- and boron-doped CVD diamonds compared with type Ib and undoped CVD diamonds. The CL spectrum of nitrogen-doped CVD diamond shows some luminescent centers, which are not observed in undoped one. Especially 2.15 eV (575 nm) and 1.67 eV (GRl) centers are prominent. CVD diamond doped with both nitrogen and boron shows a similar CL spectrum to boron-doped CVD diamond at lower concentration of nitrogen, and shows a spectrum composed of the centers obtained by nitrogen-doping and by boron-doping at higher concentration of nitrogen. Highenergy electron irradiation to nitrogen-doped CVD diamond produces an intense luminescent center having a zero-phonon line at 3.19 eV, and the following annealing make the emission of 2.15 eV center much more intense.
Electrical Properties of Homoepitaxial Diamond Films
Authors: Gildenblat G. Sh. , Grot S. A. , Hatfield C. W. , Wronski C. R. , Badzian A. R. , Badzian T. , Messier R. 
Published: March 2011

ABSTRACTWe describe the electrical characteristics of boron doped homoepitaxial diamond films fabricated using a plasma assisted CVD process, formation of ohmic contacts, high temperature (580°C) Schottky diodes, and a rudimentary diamond MESFET. We also report reversible changes of the conductive state of the diamond surface by various surface treatments for both natural and thin-film diamonds.
Electrical Contacts to Polycrystalline B Doped Diamond Films
Authors: Nishimura K. , Das K. , Iwase M. , Glass J. T. , Kobashi K. 
Published: March 2011

ABSTRACTB doped diamond films were synthesized by microwave plasma CVD and electrical contacts were fabricated by R F sputtering. Rc was obtained for Pt, Ni, TaSi2, and Al asdeposited contacts at room temperature. Pt gave the minimum Rc and Al gave the maximum Rc of the metals investigated on films containing a carrier concentration of 5 × 1018/cm3. The minimum Rc, 8.6 × 10−4 Ω cm 2, was obtained on heavily B doped diamond films with a carrier concentration of 2.7 × 1020/cm3. After nnealing at 400 °C, the Rc of Pt contacts on B doped diamond films with a resistivity of 2×104 Ω1 cm decreased by approximately one order of magnitude.
Doping Effect in Hydrogenated Amorphous Carbon Thin Films by Ion Implantation
Authors: Wong S. P. , Peng Shaoqi 
Published: March 2011

ABSTRACTHydrogenated amorphous carbon (a-C:H) thin films have been prepared by rf glow discharge decomposition of C6H5CH3gas at 13.6 MHz. Multi-energy boron or phosphorus implantation into these films has been performed to achieve a relatively flat impurity profile and the doping effect as a function of implanted impurity concentration has been studied. It is found that there are critical values of the implanted boron and phosphorus concentration below which there is no significant change observed in the electrical conductivity activation energy Ea, and the room temperature conductivity σRTincreases only slightly with the impurity concentration. When the critics values are reached, there are first an abrupt decrease in Eaand an abrupt increase in σRT. Then Eadecreases and σRTincreases gradually with further increase in impurity concentraton. The values of the critical concentrations are also found to be dependent on the substrate temperature during deposition. The critical concentrations are lower for lower deposition substrate temperatures. Preliminary results on the comparison between the doping effects by B+and BF2implantation show that the doping efficienty by BF2implantation is much higher.
Optical Band Gap of Diamond-Like Carbon Films as a Function of RF Substrate Bias
Authors: Pastel P. W. , Varhue W. J. 
Published: March 2011

ABSTRACTDiamond-like carbon films have been deposited with a low temperature 2.45 GHz electron cyclotron resonance plasma enhanced chemical vapor deposition system. The bombarding ion energy was independently controlled with a RF bias to the substrate. The production rate of reactant species and the impinging ion energy are decoupled with this system. The optical band gap decreased from 2.7 to 1.2 eV as substrate bias was increased from 0 to -140 V.
Step-Controlled Epitaxial Growth of SiC
Authors: Matsunani Hiroyuki , Ueda Tetsuzo , Nishino Hironori 
Published: March 2011

ABSTRACTVapor phase epitaxial(VPE) growth of SIC on 6H-SiC substrates has been carried out at 1500°C or below. On well-oriented (0001)Si faces, twin crystalline 3C-SiC with double positioning boundaries was grown, whereas on off-oriented (0001)Si faces, single crystalline 6H-SiC was grown with a very smooth surface. This temperature is more than 300°C lower in comparison with that for 6H-SiC VPE growth reported previously. By the introduction of offorientation, the density of surface steps is increased. Crystal growth occurs through lateral growth from the steps. The surface morphology of grown layers on off-oriented substrates, however, varied with the offdirection and the polarity of substrates. Grown layers are characterized by etch-pits observation, photoluminescence(PL) measurements and reflection high energy electron diffraction. On the basis of these experimental results, the growth mechanism on (0001)Si and (0001)C faces of 6H-SiC is discussed. P-type doping is tried, and electrical and PL properties are examined. Pn junction fabrication is also studied.
Growth of 6H-SiC on CVD-Grown 3C-SiC Substrates
Authors: Yoo Woo Sik , Matsunami Hiroyuki 
Published: March 2011

ABSTRACTPolytype control and crystal growth on 3C-SIC substrates have been investigated by using a sublimation growth technique. Single crystalline 3C-SiC(100) films (∼10μm thick) grown on Si (100) were used as substrates after removing Si by etching with a HF+HNO3 mixture. Polytypes of crystals grown on 3C-SiC(100) were examined by photoluminescence, Raman scattering, X-ray diffraction and reflection high energy electron diffraction analyses. Polytypes of grown crystals change from cubic 3C-modification to hexagonal 6H-modification with temperature increase. 6H-SiC(0114) was grown on 3C-SiC(100) substrates at high temperatures. For the first time, polytypes of grown crystals were controlled to be 3C- and 6H-modifications, and the reproducibility of polytype control was confirmed through many growth runs. 6H-SiC ingots up to 20mm in diameter and 10mm in length were grown on 3C-SiC for 6 hours. The growth mechanism of 6H-SiC on 3C-SiC was discussed based on experimental study of thermal stability of 3C-SIC. Electrical properties of 6H-SiC ingots were investigated.
Epitaxial Thin Film Growth and Device Development in Monocrystalline Alpha and Beta Silicon Carbide
Authors: Davis Robert F. , Palmour J. W. , Edmond J. A. 
Published: March 2011

ABSTRACTHigh purity monocrystalline β-SiC films have been chemically vapor deposited on Si (100) and α-SiC (0001) by numerous groups around the world using SiH4 and C3H8 or C2H4 carried in H2. Films grown on nominal Si (100) contain substantial concentrations of dislocations, stacking faults and inversion domain boundaries; those deposited on α-SiC (0001) contain primarily double positioning boundaries. Both types of boundaries may be eliminated by using off-axis orientations of the respective substrates. However, the films grown on off-axis a substrates were the a(6H) polytype. Schottky diode, p-n junction, MESFET, MOSFET and HBT devices have been fabricated with encouraging results for future commercial applications. The barrier heights and ideality factors of Au Schottky diodes on β-SiC ranged from 0.9—1.15 eV and 1.2—1.6, respectively. However, the reverse leakage currents were much lower and the breakdown voltages considerably higher at all temperatures for the diodes on the α-SiC films. MESFETs fabricated using the diodes in the alpha films were superior to those in beta with the transconductance being more than 15 times greater in the former. Enhancement-and depletion-mode MOSFETs exhibited better behavior in terms of saturation, drain voltage and high temperature operation. All films produced on a-SiC substrates were superior to those produced in beta films grown on Si.