bluuebunny/crossref_metadata_2025_split huggingface dataset:
Atomic Hydrogen Assisted Growth of Si-Ge Heterostructures on (001) Si
Authors: Baribeau J.-M. , Lockwood D.J. , Rolfe S.J. , Syme R.W.G. , Labbé H.J. 
Published: September 2012

AbstractA study of the interface chemical and physical abruptness of Si-Ge heterostructures grown on (001) Si by molecular beam epitaxy under atomic hydrogen exposure is reported. Atomic hydrogen (AH) was produced by the dissociation of molecular hydrogen interacting with a hot tungsten filament. Secondary-ion mass spectroscopy (SIMS) of structures made of alternating Ge (0.5 nm)/Si (40 nm) layers demonstrated that AH can effectively suppress Ge surface segregation. The segregation length was reduced from 1.5 nm to about 0.5 nm in films grown at a hydrogen partial pressure of −5 × 10-3 Pa and cell temperature of 2140 °C with an estimated cracking efficiency of ~5%. However, the high hydrogen background pressure had detrimental effects on the physical sharpness of the interfaces. This was evidenced by comparing the interface quality of Si/Ge atomic layer superlattices grown with and without AH exposure. X-ray reflectivity and Raman spectroscopy revealed a significant increase of the interface roughness, although the periodic character and the good crystallinity of the structures were preserved.
Surface Reactions During the Deposition of Ge from Chemical Sources on Ge(100)-(2×1)
Authors: Michael Greenlief C. , Chen Jihong 
Published: September 2012

AbstractThe adsorption and decomposition of diethylgermane, triethylgermane, and digermane on the Ge(100) surface are investigated with the intent of elucidating the surface processes leading to the deposition of epitaxial Ge films. Room temperature adsorption of diethylgermane or triethylgermane leads to the formation of surface germanium hydrides and ethyl groups. The ethyl groups decompose at higher temperatures and form ethylene via a β-hydride elimination reaction. Isotopic labeling experiments are used to confirm this reaction step. This is in contrast to the Si(100) surface where both α- and β-hydride elimination is observed for the decomposition of surface ethyl groups. The adsorption and reaction of digermane with the Ge surface is also determined to help provide a comparison with the ethylgermanes. Low energy electron diffraction is used to evaluate the quality of the deposited germanium films.
Physics and Control of Si/Ge Heterointerfaces
Authors: Fukatsu S. , Usami N. , Sunamura H. , Shiraki Y. , Ito R. 
Published: September 2012

AbstractWe describe physics and control of Si/SiGe heterointerfaces. A clear distinction will be made between the vertical and lateral effects of the Si/SiGe interface from the viewpoint of interface engineering. Ge surface segregation during nonequilibrium MBE growth and surfactant-mediated-growth are highlighted as prominent examples for the vertical effects while interface microroughness is addressed for the lateral effects. The influence of the interface effects on radiative recombination of indirect excitons is described in the context of SiGe-based optoelectronic applications.
Growth of ZnSe-Based Compounds on Ge-Terminated GaAs Surface
Authors: Saitoh T. , Tsujimura A. , Nishikawa T. , Watakabe A. , Sasai Y. 
Published: September 2012

AbstractGrowth of ZnSe-based compounds on the GaAs surface terminated by ultra-thin Ge epitaxial layer was carried out by molecular beam epitaxy and the influence of Ge layer on the growth of ZnSe was investigated. When the thickness of Ge layer was 1 atomic layer (AL), 2-dimensional growth occurred in the initial stage of ZnSe layer growth and anti-phase boundary (APB) free ZnSe layer was obtained. For Ge layer thickness of 10 AL, ZnSe grew 3-dimensionally and APBs were generated in the ZnSe layer. The crystalline quality of ZnMgSSe layer was also strongly influenced by the thickness of Ge layer. These phenomena were identified to be due to the transition of Ge surface structure from single domain to double domain with increasing Ge layer thickness.
Anisotropy in Atomic-Scale Interface Structure and Mobility in Inas/Ga1_Xinxsb Superlattices
Authors: Lew A. Y. , Zuo S. L. , Yu E. T. , Miles R. H. 
Published: September 2012

AbstractWe have used cross-sectional scanning tunneling microscopy to study the atomic-scale interface structure of InAs/Ga, _In.xSb superlattices grown by molecular-beam epitaxy. Detailed, quantitative analysis of interface profiles obtained from constant-current images of both (110) and (1ī0) cross-sectional planes of the superlattice indicates that interfaces in the (1ī0) plane exhibit a higher degree of interface roughness than those in the (110) plane, and that the Ga1-xln xAs interfaces are rougher than the InAs-on-Gal1-xInxSb interfaces. The roughness data are consistent with anisotropy in interface structure arising from anisotropic island formation during growth, and in addition with a growth-sequence-dependent interface asymmetry resulting from differences in interfacial bond structure between the superlattice layers. Roughness data are compared with measurements of anisotropy in low-temperature Hall mobilities of the samples.
Surface Reconstruction and Morphology of Hydrogen Sulfide Treated GaAs (001) Substrate
Authors: Suda Jun , Kawakami Yoichi , Fujita Shizuo , Fujita Shigeo 
Published: September 2012

AbstractWe report several new results in hydrogen sulfide (H2S) treatment of a GaAs (001) substrate. Surface reconstruction and morphology were investigated by in situ reflection high energy electron diffraction (RHEED) and ex situ atomic force microscopy (AFM) in terms of the annealing temperature and the H2S irradiation sequence. A (4 × 3) GaAs surface was obtained by annealing the substrate under H2S irradiation (4 × 10-7 Torr). The surface was atomically flat, i.e., large terraces with monolayer steps were clearly observed. A (2 × 6) S-terminated GaAs surface was obtained by irradiation H2S at 300°C on a Ga-terminated surface, which was formed by annealing at 580°C in high vacuum. The molecular beam epitaxy (MBE) growth of ZnSSe-based semiconductors on the (4 × 3) surface results in high quality structures such as a novel ZnSSe/ZnMgSSe tensile-strained quantum well (QW).
Surface Roughening and Composition Modulation of ZnSe-related II-VI epitaxial films
Authors: Tomiya Shigetaka , Tsukamoto Hironori , Itoh Satoshi , Nakano Kazushi , Morita Etsuo , Ishibashi Akira 
Published: September 2012

AbstractWe have investigated ZnSSe and ZnMgSSe epitaxial layers lattice-matched to GaAs (001) substrates grown by molecular beam epitaxy using atomic force microscopy and transmission electron microscopy. Under II-rich conditions with c(2x2) surface reconstruction, surface morphology exhibited corrugation aligned in the [1ī0] direction and composition modulation was observed in the same [1ī0] direction. Under VI-rich condition with (2x1) surface reconstruction, the surface morphology becomes rounded grain-like and composition modulation was not observed. The formation of composition modulation is associated with the surface corrugated structures.
Direct Bandgap Quantum Wells on GaP
Authors: Lee Jong-Won , Schremer Alfred T. , Fekete Dan , Shealy James R. , Ballantyne Joseph M. 
Published: September 2012

AbstractCurrently, there are no direct-bandgap alloy semiconductors that can be grown lattice-matched to GaP substrates. A strained layer of GaInP can be grown on GaP, however, with difficulties. First, GaInP is an indirect-bandgap material for In concentrations up to ∼30%. Second, the band alignment between GaInP and GaP is type-II for In concentrations up to ∼60%. The Mathews-Blakeslee critical thickness of GaInP layer on GaP is prohibitively small in the useful In concentration range. GaInP is known to grow in an ordered phase in certain growth conditions. By changing the growth conditions, a heterojunction of ordered GaInP and disordered GaInP can be grown. The conduction band offset going from a disordered GaInP phase to an ordered GaInP phase has been reported to be about 150 meV. Using a layer of ordered GaInP, a QW with type-I band alignment may be grown on GaP for a wider range of composition.We have grown a series of approximately 60 Å thick GaP/GaInP/GaP strained quantum wells of various compositions using OMVPE. Strong photoluminescence, which exhibited an unusual temperature dependence, has been observed on many samples. A study of the QW’s using X-ray diffraction, TEM, and variable temperature PL reveals behaviors consistent with direct bandgap GaInP quantum wells containing ordered and disordered domains.
Formation of Large Conduction Band Discontinuities of Heterointerfaces Using CdF2 AND CaF2 on Si(111)
Authors: Izumi Akira , Matsubara Noriyuki , Kushida Yusuke , Tsutsui Kazuo , Sokolov Nikolai S. 
Published: September 2012

AbstractWe proposed use of a new CdF2/CaF2 heterointerface for the formation of large conduction band discontinuities to apply quantum effect devices fabricated on Si substrates. Resonant tunneling diodes using this heterointerface on Si were fabricated and negative differential resistance whose P/V current ratio of 24 at highest was observed at room temperature.
Comparison of the Morphological and Optical Characteristics of InP Islands on GalnP/GaAs (311)A and (100)
Authors: Pelzel R. I. , Reaves C. M. , DenBaars S. P. , Weinberg W. H. 
Published: September 2012

AbstractWe have studied the effect of surface orientation on the optical and morphological characteristics of coherently-strained InP islands grown on GaInP/GaAs. The differences between islands grown on the (100) orientation and the (311)A orientation are studied. Islands grown on the (311)A orientation are more dense than the islands grown on the (100) orientation. For the (100) orientation, the island height distribution is bimodal peaked at 20 Å and 220 Å. For the (311)A orientation, the island height distribution is also bimodal peaked at 15 Å and 60 Å. Photoluminescence measurements for the (311)A orientation show a peak at 1.9 eV attributed to small islands. This peak is shifted to higher energies in comparison to the corresponding peak for the (100) orientation which is at 1.77 eV. This peak shift is due to the fact that the small islands on the (311)A orientation are smaller than the corresponding islands on the (100) orientation.
Structural Investigations of Self-Assembled Ge-Dots by X-Ray Diffraction and Reflection
Authors: Darhuber A.A. , Holy V. , Stangl J. , Bauer G. , Schittenhelm P. , Abstreiter G. 
Published: September 2012

AbstractSelf-organized Ge-dots on (001)-oriented Si-substrates have been studied using two-dimensionally resolved high resolution x-ray diffraction and reflectivity. The degree of the vertical correlation of the dot positions ("stacking") has been derived as well as a lateral ordering of the dots in a (disordered) square array with main axes parallel to ]100] and ]010].
Improvement of InGaP/GaAs Heterointerface Quality by Controlling AsH3 Flow Conditions
Authors: Fukai Yoshino K. , Hyuga Fumiaki , Nittono Takumi , Watanabe Kazuo , Sugahara Hirohiko 
Published: September 2012

AbstractThis paper examines the conduction band offset, ∆Ec, and interface charge density, σ, of disordered InGaP and GaAs heterointerfaces by controlling the AsH 3 cover time and flow rate at the growth interval from GaAs to InGaP. Short AsH, cover time (0.05 min) creates high ΔEc of 0.2 eV and low σ of 6.3×l0 10cm −2. Extending the AsH 3 cover time by 50 times cuts ΔEc to almost 0 eV and increases σ by one order. Interface morphology for long-AsH3 -cover-time samples observed by atomic force microscopy shows a terrace structure on GaAs surface, which means the surface is As rich. These results suggest that an As-poor GaAs surface is essential to achieving high-quality InGaP/GaAs heterointerfaces.
Direct Formation of Fine Structure by Low Energy Focused Ion Beam
Authors: Chikyow T. , Shikanai A. , Koguchi N. 
Published: September 2012

AbstractGaAs micro crystals in line were grown on a sulfur-terminated GaAs surface by low energy focused ion beam. Ga ions, picked out from a liquid Ga ion source, were accelerated up to 10 KV to obtain a focused ion beam. The ions were given a positive bias to reduce their kinetic energy by retarding lens.The Ga ions landed on the surface softly and formed a series of Ga droplets. By subsequent As molecule supply to the Ga droplet, GaAs micro crystals in line were grown. This method was found to be useful to make fine structures directly on the semiconductor materials.
Surface Adsorption Kinetics of Ga Wire Arrays on Si(112)
Authors: Prokes S.M. , Glembocki O.J. 
Published: September 2012

AbstractThe growth and energetics of Ga chains on a Si(112) facet surface have been investigated. Low energy electron diffraction (LEED) and Reflectance Difference Anisotropy (RDA) experiments have been performed in UHV to examine the kinetics of the Ga atom chain formation process along the Si steps. This is a self-limiting process for substrate temperatures in the 400°C to 500°C range, since the binding energy of the metal atoms at the step edges is greater than that on the (11l)-type terraces. At saturation coverage, the Ga chains exhibit sixfold periodicity along the step edges, but below saturation, these chains exhibit fivefold periodicity. A model has been suggested from these results in which the periodicities of the chains are determined by the metal atom vacancies, which balance the tensile stress created by the larger metal atoms. We have used RDA to study the time evolution of the surface kinetics and changes in the surface reconstruction of Ga deposited on these facet (112) Si surfaces, as a function of substrate temperature and Ga deposition rate. The RDA measurement is shown to be sensitive to the formation of both the 5×1 as well as 6 × 1 reconstructions and to island formation at low substrate temperatures. The diffusion-controlled Ga line formation process at low temperatures has also been characterized as well as the evaporation controlled regime, which is evident at substrate temperatures over 400°C.
Ultra Thin SiO2 Mask Layer for Nano-Scale Selective-Area Pecvd of Si
Authors: Park J. W. , Yasuda T. , Ikuta K. , Kuo L.H. , Yamasaki S. , Tanaka K. 
Published: September 2012

AbstractWe discuss the applicability of ultrathin SiO2 layers as a mask for low-temperature selective-area deposition of Si. Thin oxide layers with estimated thickness ranging from 4 to 20 Å were formed by oxidizing H-terminated Si(100) surfaces by a remote plasma exposure at room temperature. Low-temperature selective-area deposition was carried out using two different techniques: flow-modulated plasma-enhanced chemical vapor deposition (FM-PECVD) using SiH4 and H2, and very low pressure CVD (VLPCVD) using Si2H4. We show that the ultra-thin plasma oxide layers exhibit good properties for a use as a passivating mask layer, and that the oxide layer can be patterned directly by E-beam irradiation. These results open up a possibility to realize Si-nanostructures formation by selective-area processing. Degradation of the oxide layer by plasma processing is also discussed.
Interfacial Arsenic from Wet Oxidation of AlxGa1-xAs/GaAs: Its Effects on Electronic Properties and New Approaches to Mis Device Fabrication
Authors: Ashby Carol I.H. , Sullivan John P. , Missert Nancy A. , Newcomer Paula P. , Hou Hong Q. , Hammons B.E. , Hafich Michael J. , Baca Albert G. 
Published: September 2012

AbstractThree important oxidation regimes have been identified in the temporal evolution of the wet thermal oxidation of AlxGa1-xAs (1 ≥ x ≥ 0.90) on GaAs: 1) oxidation of Al and Ga in the AlxGa1-xAs alloy to form an amorphous oxide layer, 2) oxidative formation and elimination of elemental As (both crystalline and amorphous) and of amorphous As2O3, and 3) crystallization of the oxide film. Residual As can result in up to a 100-fold increase in leakage current and a 30% increase in the dielectric constant and produce strong Fermi-level pinning and high leakage currents at the oxidized AlxGa1-xAs/GaAs interface. The presence of thermodynamically-favored interfacial As may impose a fundamental limitation on the application of AlGaAs wet oxidation for achieving MIS devices in the GaAs material system.
Nitridation of Si(111)−7×7 Surface by Low Energy Nitrogen Ions : STM Investigation
Authors: Sook Ha Jeong , Park Kang-Ho , Soo Yun Wan , Lee El-Hang , Park Seong-Ju 
Published: September 2012

AbstractThe surface structure of Si(111) post-annealed at 980 °C after nitrogen ion induced nitridation has been investigated by using a scanning tunneling microscope (STM) and low energy electron diffraction (LEED). The LEED and STM results indicated the formation of ordered domain of quadruplet structure in the silicon nitride layer. The LEED pattern taken from the nitrated Si(111) surface showed a coexistence of 7×7 domain with quadruplet one. In the STM image taken from the same surface, a three directional periodicity with a periodic arrangement of white protrusions was observed in the local area of silicon nitride island and its symmetry directions were rotated about 10° with respect to those of Si(111) surface. In addition to the quadruplet structure of the silicon nitride island, meta-stable structures such as 9×9, c(4×2), and 2×2 as well as 7×7 phase boundaries were observed to have been formed on the Si(111) surface during the rapid cooling of nitrated surface from the post-annealing temperature of 980 °C. The investigation of the surface structure of nitrated Si(111) showed that the surface nitrated at high temperature had better epitaxial silicon nitride layer than that post-annealed after nitridation at room temperature.
Chemically Stable Semiconductor Surface Layers Using Low-Temperature Grown GaAs
Authors: Janes D.B. , Hong S. , Kolagunta V. R. , McInturff D. , NG T.-B. , Reifenberger R. , West S.D. , Woodall J.M. 
Published: September 2012

AbstractThe chemical stability of a GaAs layer structure consisting of a thin (10 nm) layer of low-temperature-grown GaAs (LTG:GaAs) on a heavily n-doped GaAs layer, both grown by molecular beam epitaxy, is described. Scanning tunneling spectroscopy and X-ray photoelectron spectroscopy performed after atmospheric exposure indicate that the LTG:GaAs surface layer oxidizes much less rapidly than comparable layers of stoichiometric GaAs. There is also evidence that the terminal oxide thickness is smaller than that of stoichiometric GaAs. The spectroscopy results are used to confirm a model for conduction in low resistance, nonalloyed contacts employing comparable layer structures. The inhibited surface oxidation rate is attributed to the bulk Fermi level pinning and the low minority carrier lifetime in unannealed LTG:GaAs. Device applications including low-resistance cap layers for field-effect transistors are described.
Spectroscopic Investigation of Lithium Intercalation in Thin Films of Anatase Titanium Dioxide
Authors: Van De Krol R. , Goossens A. , Schoonman J. 
Published: September 2012

AbstractThin films of anatase TiO2 have been deposited on tin-doped indium oxide (ITO) and Sb-doped tin oxide using electron beam evaporation. Subsequently these samples have been mounted into an electrochemical cell. Assuming a composition of LixTiO2 with x being 0.5 or 1, voltammetric measurements show that all lithium is present within the first 15 or 7.5 nm of the TiO2 film, respectively. Stepped potential experiments in combination with optical transmission measurements show that de-intercalation is much faster than intercalation. Differential absorption spectra as a function of intercalation potential suggest that the observed dark coloring of intercalated anatase can be attributed to electron traps at Li+ sites. This contradicts assumptions made in literature that the coloring mechanism of anatase is based on intervalence charge transfer from Ti4+ to Ti3+.
Interface properties of Si3N4/Si/n-GaAs metal-insulator-semiconductor structures grown on GaAs(111)B substrate
Authors: Park D.G. , Diatezua D. M. , Chen Z. , Mohammad S. N. , Morkoç H. 
Published: September 2012

AbstractWe present characteristics of Al/Si3N4/Si/n-GaAs metal-insulator-semiconductor (MIS) interfaces grown on GaAs(111)B prepared with a combination of in situ molecular beam epitaxy (MBE) and chemical vapor deposition (CVD) techniques . The density of the surface states in the high 1010 eV-1 cm-2 near the GaAs midgap for the GaAs grown at 575°C and 625°C was obtained. The MIS structure with GaAs homoepitaxial layer grown at 625°C, showing smoother surface morphology than the surface grown at 575 °C, exhibited small hysteresis which was as small as 30 mV under a field excursion of 1.5 MV/cm. The presence of a 1 MHz frequency response at 77 K suggests that the traps be within 60 meV of the conduction band edge of GaAs.
Characterization of GaAs Surfaces Subjected to A Cl2/Ar High Density Plasma Etching Process
Authors: Eddy C.R. , Glembocki O.J. , Shamamian V.A. , Leonhardt D. , Holm R.T. , Butler J.E. , Thoms B.D. , Pang S.W. , Ko K.K. , Berg E.W. , Stutz C.E. 
Published: September 2012

AbstractHigh density plasma etching of III-V compound semiconductors is critically important to the development of advanced optoelectronic and high frequency devices. Unfortunately, the surface chemistry of these processes is not well understood. In an effort to monitor surface processes and their dependence on process conditions in a realistic etching environment, we have applied mass spectroscopic techniques for the study of GaAs etching in Cl2/Ar chemistry. Etch product chlorides were monitored, together with optical measurement of the surface temperature by diffuse reflectance spectroscopy, as pressure (neutral flux), microwave power (ion flux) and rf bias of the substrate (ion energy) were varied. Observations from the spectroscopic techniques were correlated with ex situ surface damage assessments of unpassivated surfaces by photoreflectance spectroscopy. As a result, insights are made into regions of process conditions that are well suited to anisotropic, low damage etching.
Interfacial Layer Formation of a Heat Treated Teos Based Oxide Prepared by a Pecvd Technique
Authors: Lee T.J. , Jeong D.S. , Song C.S. , Lee S.Y. , Park C.H. 
Published: September 2012

AbstractAn interfacial layer is formed between the TEOS(tetraethylorthosilicate) based oxide and silicon substrate when the oxide is thermally treated and it shows unique properties by leaving a unremovable layer in an H F(hydrofluoric acid) dipping. While the interface formed in the temperature range of 950 - 1100 °C demonstrates hydrophilic state, it renders the surface hydrophobic in the higher range of 1150 - 1200 °C. Its characteristics are analyzed by ESCA and the measurement of water contact angle on the silicon surface after stripping the oxide.
Suppression of Surface SiO2 Layer and Solid Phase Epitaxy of Amorphously Deposited Si Films using Heating-Up Under Si2H6 Environment
Authors: Choe Tae-Hee , Kim Se-June , Choi Woon , Kim Hyoung-June 
Published: September 2012

AbstractA novel technique to realize a selectively grown Si epitaxy layer has been developed. This technique consists of deposition of amorphous Si with oxide-free Si surface, selective solid phase epitaxial (SPE) growth on Si windows, and etching of uncrystallized amorphous Si on SiO2 layer. Formation of surface oxide can be effectively suppressed by flowing Si2H6 gas during heating-up stage to the deposition temperature. This method enables us to grow epitaxial layer without any high temperature cleaning procedures. Substantially higher growth rate of vertical SPE on Si windows over lateral SPE on SiO2 regions allows the growth of thick SPE layer with a minimized lateral overgrowth. With a proper etching solution, the remaining amorphous Si on SiO2 layer can be readily etched to form a selectively defined epitaxial layer on Si windows.