bluuebunny/crossref_metadata_2025_split huggingface dataset:
Amorphous Silicon Films from Dichlorosilane and SiH4 for Solar Cells
Authors: Payne A. M. , Wagner S. 
Published: April 2011

AbstractWe have deposited amorphous silicon films from mixtures of dichlorosilane (SiH2C12, DCS), and silane (SiH4) and made the first p-i-n solar cells using i-layers of this material. We measured optical and electronic transport properties of the DCS-derived films and relate them to the solar cell performance. The DCS cells are compared to standard cells made with SilH4.
A Simple Optical Properties Modeling of Microcrystalline Silicon by the Effective Medium Approximation Method
Authors: Cho Woo Yeong , Cho Hyun-Mo , Lim Koeng Su 
Published: April 2011

AbstractThe optical properties of microcrystalline silicon (μc-Si) were estimated using the EMA (Effective Medium Approximation) method. This modeling was based on two-phase mixture, amorphous silicon (a-Si) and crystalline silicon (c-Si) with volume fractions of fa and fc respectively. From this modeling, it could be possible to understand that μc-Si has lower light absorption characteristics than a-Si over all solar spectrum by considering hydrogen involvement in embedded a-Si part of μc-Si and crystalline volume fraction. Also, it is proposed that p-type μc-Si is superior to n-type μc-Si because of its high optical gap of Eo4 and its low absorption coefficient spectrum shape.
Intrinsic N-Type Modulation Doping in Inp-Based Heterostructures
Authors: Chen W.M. , Buyanova I.A. , Buyanov A. , Bi W.G. , Tu C.W. 
Published: April 2011

AbstractWe propose and demonstrate a new doping approach, i.e. intrinsic doping, for n-type modulation doping in InP-based heterostructures. Instead of the conventional method of n-type doping by shallow donor impurities, grown-in intrinsic defects are utilized to provide the required doping without external doping sources. The success of this approach is clearly demonstrated by our results from InGaAs/InP heterostructures, where the required n-type doping in the InP barriers is provided by Pin antisites, preferably introduced during off-stoichiometric growth of InP at low temperatures (LT-InP) by gas source molecular beam epitaxy. A twodimensional electron gas (2DEG) is shown to be formed near the InGaAs/InP heterointerface as a result of electron transfer from the LT-InP to the InGaAs active layer, from studies of Shubnikov-de Haas oscillations and photoluminescence. The concentration of the 2DEG is determined to be as high as 1.15×1012 cm−2, where two subbands of the 2DEG are readily occupied.
Complementary Hfet Technology for Low-Power Mixed-Mode Applications
Authors: Baca A. G. , Sherwin M. E. , Zolper J. C. , Dubbert D. F. , Hietala V. M. , Shul R. J. , Sloan L. R. , Hafich M. J. 
Published: April 2011

AbstractDevelopment of a complementary heterostructure field effect transistor (CHFET) technology for low-power, mixed-mode digital-microwave applications is presented. An earlier digital CHFET technology with independently optimizable transistors which operated with 319 ps loaded gate delays at 8.9 fJ is reviewed. Then work demonstrating the applicability of the digital nJFET device as a low-power microwave transistor in a hybrid microwave amplifier without any modification to the digital process is presented. A narrow band amplifier with a 0.7 × 100 μm nJFET as the active element was designed, constructed, and tested. At 1 mW operating power, the amplifier showed 9.7 dB of gain at 2.15 GHz and a minimum noise figure of 2.5 dB. In addition, next generation CHFET transistors with sub 0.5 μm gate lengths were developed. Cutoff frequencies, ftof 49 GHz and 11.5 GHz were achieved for n- and p-channel FETs with 0.3 and 0.4 μm gates, respectively. These FETs will enable both digital and microwave circuits with enhanced performance.
Investigation of Deep-Level Defects in 10 Mev Electrons Irradiated Si-Gaas
Authors: Wu Fengmei , Zhao Zhouying , Li Haifeng 
Published: April 2011

AbstractThe deep-level defects in 10 MeV electron irradiated undoped semi-insulating (SI) LEC GaAs were investigated. The results show that the density of EL2 (Ec-0.83eV) and EL12 (Ec-0.69eV) defects increases and the density of EL6 (Ec-0.39eV) and EL3 (Ec-0.58eV) defects decreases in irradiated SI-GaAs at higher fluence levels. At lower fluences, we observe decrease in density of EL2 and EL12 defects, however, the density of the EL6 and EL3 defects is increased. It could be related mainly to the dissociation of the EL2 and EL12 defects. The influence of 10 MeV electrons irradiation on the resistivity will also be discussed.
High Quality In1-x(Gax)AsyP1-y/InP Compressive Strained Quantum Well Structures Grown by LP-MOCVD
Authors: Zhu J. T. , Clawson A. R. , Yu P. K. L. 
Published: April 2011

AbstractWe report the results of the growth of InAsyP1−y /InP and In0.86Ga0.14AS0.51P0.49/ In0.86Ga0.14As0.33P0.67 compressive strained multiple quantum wells (CSMQW) structures grown by low pressure metalorganic chemical vapor deposition (LP-MOCVD). Our studies showed high quality 1.06 μm InAs0.21P0.79/InP CSMQW structure with 6 periods can be obtained when the growth temperature is around 650°C and the pressure in the reactor is about 20 Torr. When the well thickness and composition are tuned for wavelength around 1.30 μm, the quality of this structure degrades. By employing 1.1 μm wavelength, lattice-matched InGaAsP as the barrier layers and setting the growth temperature at 600 °C, high quality 1.30 μm wavelength In0.86Ga0.14AS0.51P0.49/ In0.86Ga0.14As0.33P0.67 CSMQW materials with 10 periods can also be obtained. The materials were characterized with high resolution x-ray rocking curves, room and low temperature photoluminescence (PL). The 15K full-width-at-half-maximums (FWHM) of the PL peaks for 1.06 μm InAs0.21P0.79/InP and 1.30 μm In0.86Ga0.14AS0.51P0.49/ In0.86Ga0.14As0.33P0.67 CSMQW structures are 5.6 meV and 4.97 meV, respectively, which are among the smallest FWHMs reported up to date for these kinds of MOCVD growth materials. Buried heterostructure lasers at 1.3 μm wavelength have been obtained with the CSMQWs as the active layer.
Luminescence Decay of the 1.54 μm Emission from Erbium in Silicon
Authors: Hartung J. , Evans J. H. , Dawson P. , Sciioles A. P. , Taskin T. , Huda M. Q. , Jeynes C. , Peaker A. R. 
Published: April 2011

AbstractPhotoluminescence of silicon implanted with erbium and oxygen was measured in the time domain focussing on the temperature and excitation density dependence of the intra-4f-shell emission from Er3+. The decay of this luminescence is similar for the different optically active crystal field split Er-centres. At low temperatures the luminescence transients consist of a fast initial non-exponential component followed by slower exponential behaviour. An increase in excitation density results in a higher proportion of the luminescence decaying with the faster decay time. Our results indicate a relation of the fast component to nonradiative processes. Auger recombination is proposed as a possible mechanism.
Defect Engineering in SI:ER Technology
Authors: Sobolev N. A. , Alexandrov O. V. , Bresler M. S. , Emtsev V. V. , Gusev O. B. , Poloskin D. S. , Shek E. I. 
Published: April 2011

AbstractRecent results contributing to our understanding of mechanisms of defect formation and excitation of Er luminescence in Si:Er system are presented. An essential role of non-equilibrium intrinsic point defects in Er-related defects formation for both implanted and in-diffused Si:Er structures is demonstrated.The data of electroluminescence (EL) measurements evidence that the Er3+ excitation occurs via capture of free excitons on neutral Er-related donor centers with subsequent Augerrecombination of bound excitons.
Growth Conditions of Erbium-Oxygen-Doped Silicon Grown by MBE
Authors: Stimmer J. , Reittinger A. , Abstreiter G. , Holzbrecher H. , Buchal Ch. 
Published: April 2011

AbstractWe report on a systematic study of the growth parameters of erbium-oxygen-doped silicon grown by molecular beam epitaxy. The surface quality of the grown layers was measured in situ by RHEED. The samples were characterized by photoluminescence measurements and SIMS. An Er-O-doped Si light emitting diode grown with the optimized parameters is presented.
Exafs and X-ray Ctr Scattering Characterization of Er Doped in InP by Omvpe
Authors: Tabuchi M. , Kawamura D. , Fujita K. , Matsubara N. , Yamada N. , Ofuchi H. , Ichiki S. , Fujiwara Y. , Takeda Y. 
Published: April 2011

AbstractEr-doped semiconductors are considered to be important for optical communication systems since one of the prominent luminescent peaks of Er is in the minimum absorption region of silica based fiber and wavelength of the luminescence is insensitive to the ambient temperature. In this work, OMVPE grown InP samples uniformly and δ-doped with Er were investigated by EXAFS and X-ray CTR measurements. The EXAFS measurement revealed that the uniformly doped Er atoms in InP grown at 580°C formed NaCl-structure ErP, and at 530°C occupied the In-sites. The X-ray CTR measurement revealed that the δ-doped Er atoms in InP at 530'C formed NaCl-structure ErP. In the sample, the total number of Er was analyzed to be about 0.171ML(monolayer), and the FWHM of Er distribution was about 5ML. By comparing the results of PL measurement with those of the EXAFS and the X-ray CTR measurements, it was suggested that the Er atoms on In-sites show high efficiency of luminescence and the Er atoms in the NaCl-structure ErP low efficiency.
Activation of Yb Luminescence in GaAs by Group VI Elements Codoping
Authors: Konnov V. M. , Larikova T. V. , Loyko N. N. , Dravin V. A. , Ushakov V. V. , Gippius A. A. 
Published: April 2011

AbstractYb in GaAs is generally believed to be optically inactive due to very low fraction of Yb in substitutional position. In the present work it is demonstrated that Yb can be rendered optically active in GaAs if it is incorporated in three-component complexes (Yb+O+S/Se/Te).
Segregation and Trapping of Erbium in Silicon at a Crystal-Amorphous or Crystal-Vacuum Interface
Authors: Polman A. , Serna R. , Custer J. S. , Lohmeier M. 
Published: April 2011

AbstractThe incorporation of erbium in silicon is studied during solid phase epitaxy (SPE) of Erimplanted amorphous Si on crystalline Si, and during Si molecular beam epitaxy (MBE). Segregation and trapping of Er is observed on Si(100), both during SPE and MBE. The trapping during SPE shows a discontinuous dependence on Er concentration, attributed to the effect of defect trap sites in the amorphous Si near the interface. Trapping during MBE is described by a continuous kinetic growth model. Above a critical Er density (which is lower for MBE than for SPE), growth instabilities occur, attributed to the formation of silicide precipitates. No segregation occurs during MBE on Si(111), attributed to the epitaxial growth of silicide precipitates.
Excitation and Recombination Processes in rare Earth Doped II–VI Semiconductors
Authors: Godlewski M. 
Published: April 2011

AbstractRare Earth (RE) doped II–VI semiconductors are currently used for production of thin film light emitting electroluminescence devices. The excitation and recombination processes in RE activated wide band gap II–VI semiconductors (ZnS, ZnSe, SrS and CaS) are reviewed. Mechanisms relevant for obtaining bright photoluminescence (energy transfer processes, RE ionisation and exciton binding), electroluminescence (impact excitation and impact ionisation) and cathodoluminescence are described based on the recent experimental results. Efficiency of the light emission from RE doped II–VI materials is limited by several processes of nonradiative recombination. The Auger-type energy transfer processes and electric field- or thermally-activated processes responsible for 4f-4f nonradiative recombination of RE ions are discussed.
Ion Beam Epitaxy of in-situ Er-O Co-Doped Silicon Films
Authors: Matsuoka Morito , Tohno Shun-Ichi 
Published: April 2011

AbstractErbium-doped silicon films are grown by ion beam epitaxy (IBE) using an electric-mirror sputtering-type metal ion source in ultrahigh vacuum. In-situ erbium doping with concentrations ranging from 1×1016 to 6×1020 cm−3 is achieved by sputtering the erbium metal pellet with ions extracted from the silicon metal ion source. The oxygen concentration in the films is also controlled in-situ over the range from below 1×1018 to 2×1020 cm−3 by using argon gases containing 1 ppb to 100 ppm of oxygen impurities. The erbium incorporation probability drastically increases (by two or more orders of magnitude) when oxygen is contained in the argon gas during film growth. Erbium is selectively oxidized in the Si host. Erbium segregation and precipitation formation are well suppressed by the oxidation. Sharp and well-split photoluminescence is clearly observed in as-deposited films grown typically at 480°C with oxygen co-doping.
Electroluminescence of Erbium in Oxygen Doped Silicon
Authors: Lombardo S. , Campisano S. U. , Van Den Hoven G. N. , Polman A. 
Published: April 2011

AbstractIt is demonstrated room-temperature electroluminescence at 1.54 μm in erbiumimplanted oxygen doped silicon (27 at. 0), due to intra-4f transitions of the Er3+. The luminescence is electrically stimulated by biasing metal-(Si:O,Er)-p+ silicon diodes. The 30 nm thick Si:O,Er films are amorphous layers deposited onto silicon substrates by chemical vapour deposition of SiH4 and N20, doped by ion implantation with Er to a concentration up to ≈ 1.5 at.%, and annealed in a rapid thermal annealing furnace. The most intense electroluminescence is obtained in samples annealed at 400°C in reverse bias under breakdown condition and it is attributed to impact excitation of erbium by hot carriers injected from the Si into the Si:O,Er layer. The electrical characteristics of the diode are studied in detail and related to the electroluminescence characteristics. A lower limit for the impact excitation cross-section of ≈6×10−16 cm2 is obtained.
Photothermally Assisted Dry Etching Of GaN
Authors: Leonard R. T. , Bedair S. M. 
Published: April 2011

AbstractPhotoassisted dry etching of GaN in HC1 by 193 nm ArF excimer laser is developed as apotential alternative process to eliminate the ion damage and surface roughness which occur inetching techniques that involve an energetic ion beam impinging the surface. A directed stream ofHC1 etchant with background pressure of ∼ 5 × 10−4 Torr, sample surface temperature between 200 to 400°C, and laser fluence of 10 to 20 mJ/ pulse combine to produce etching. The photoassistedetching reaction under these process conditions is thermal in nature, with activation energy near 1.2kcal/ mol. Increases in laser fluence results in increase of etch rate, but the surface also becomesrougher. Distinct etch features can be produced with smooth surfaces at expense of etch rate.
Beta Silicon Carbide Pn Junction Diodes
Authors: Coleman J. C. , Harris G. L. , Poker D. B. 
Published: April 2011

AbstractBeta silicon carbide (3C-SiC) diodes have been fabricated using ion implantation as the selective doping technique. Previous work on 3C-SiC diodes have exhibited properties such as low reverse breakdown voltages and high ideality factors. Also, 6H and 4H SiC diodes have been reported. This paper studies a different procedure to produce better 3C-SiC diodes for use in the electronics industry. Current versus voltage, capacitance versus voltage and temperature versus voltage tests were conducted on the devices.Isolation between devices is a prominent concern when building integrated circuits. Proton bombardment is the preferred planar process for forming isolation regions in gallium arsenide (GaAs) due to the lack of a stable native oxide. Hydrogen and boron in GaAs have exhibited good electrical isolation between devices. This paper investigates using proton bombardment to form isolation regions in 3C-SiC. Cubic SiC samples are implanted with a variety of implant doses, ranging from 1 × 1014 to 1 × 1015 ions / cm2 , and implant energies ranging from 150 to 300 keV. Hall measurement tests were performed to study the characteristics of the implanted material.
TEM and PL characterisation of MBE-grown epitaxial GaN/GaAs
Authors: Xin Yan , Brown P. D. , Boothroyd C. B. , Preston A. R. , Humphreys C. J. , Cheng T. S. , Foxon C. T. , Andrianov A. V. , Orton J. W. 
Published: April 2011

AbstractMBE-grown epitaxial GaN deposited at 700°C on {001}, {111}A and B GaAs has been characterised using the combined techniques of transmission electron microscopy (TEM) and photoluminescence (PL). On both { 111 } A and 111 B GaAs substrates, single crystal wurtzite GaN was formed, but with very high densities of threading defects. Best epitaxy occurred on 111B GaAs in accordance with PL measurements. An amorphous phase was identified at the GaN/{ 111 }A GaAs interface and the GaN epilayer evolved in this instance with the same Nterminated growth surface as for the case of growth on 111 B GaAs, as determined by convergent beam electron diffraction (CBED). Growth on {001} GaAs produced highly faulted columnar grains of zincblende GaN. Conversely, growth on {001} GaAs under an additional arsenic flux at 700°C resulted in the deposition of single crystal zincblende GaN with a high density of stacking faults and microtwins. Thus, the microstructure of epitaxial GaN depends very much on the detailed growth conditions and substrate orientations used.
Improved Aluminum Nitride Thin Films Grown By Mocvd From Tritertiarybutylaluminum And Ammonia
Authors: Metzger T. , Born E. , Stimmer R. , Rieger W. , Dimitrov R. , Lentz D. , Angerer H. , Ambacher O. , Stutzmann M. 
Published: April 2011

AbstractAIN thin films were grown on c-plane sapphire by metalorganic chemical vapor deposition from tritertiarybutylaluminum and ammonia at 1050°C. These films exhibit a full width at half maximum of the 002 X-ray rocking curve below 200 arcsec indicating high epitaxial quality. By measuring asymmetric reflections, a structural disorder of the lattice mainly due to edge dislocations can be observed. For further investigations, atomic force microscopy and photothermal deflection spectroscopy were performed. In order to study the effect of increasing AIN layer thickness on the optical and structural properties of GaN in an AIN/GaN heterostructure, AIN thin films with increasing thickness ranging from 0.02 to 0.36 μm were used as sublayers for the deposition of 0.75 μm thick GaN layers. Photoluminescence, micro- Raman and X-ray diffraction measurements confirm the relaxation of biaxial compressive stress in the GaN layers due to different thermal expansion coefficients by increasing AIN layer thickness. The pressure dependence of the band gap shift was determined as 24 meV/GPa for biaxial compressive stress. Our results indicate that the growth of AIN with metal organic chemical vapor deposition from tritertiarybutylaluminum and ammonia is a promising method for obtaining high quality epitaxial films.
Properties Of Homoepitaxially Mbe-Grown Gan
Authors: Suski T. , Krueger J. , Kisielowski C. , Phatak P. , Leung M. S. H. , Liliental-Weber Z. , Gassmann A. , Newman N. , Rubin M. D. , Weber E. R. , Grzegory I. , Jun J. , Bockowski M. , Porowski S. , Helava H. I. 
Published: April 2011

AbstractBulk single crystals of GaN were used for epitaxial growth of GaN films by molecular beam epitaxy. Low temperature photoluminescence yields much higher intensity emission in the near bandedge region for epitaxial films with respect to the situation in bulk crystals. Character of this luminescence changes also. Dominant band-to-band transitions in the bulk crystals are exchanged by bound exciton and/or donor-acceptor pair transitions observed in the epitaxial layers. We will compare the obtained results with the available data on the homoepitaxial samples grown by metalorganic chemical vapor deposition method and discuss the importance of establishing the basic information on energetic positions of excitonic transitions in stress free samples.
Origin of High-Conductivity Layer Near the Surface in As-Grown Diamond Films
Authors: Yamanaka Sadanori , Hayashi Kazushi , Okushi Hideyo , Kajimura Koji 
Published: April 2011

AbstractIn order to clarify the origin of p-type high-conductivity layers (HCL) near the surfaces of as-grown diamond films prepared by chemical vapor deposition, we have investigated the properties of Schottky junctions fabricated from HCL. The Schottky junctions between Al and HCL of undoped homoepitaxial films with step-flow growth showed high-rectification properties. The forward current-voltage characteristics of the junctions in the temperature range between 83 K and 400 K are found to be described by the thermionic-field emission theory. Analysis indicates that thin enough depletion layer is formed at the junction by a high concentration (∼1018/cm3) of acceptors existing in HCL due to hydrogenation. The origin of HCL is the acceptors related to incorporated hydrogen near the surface.
High Quality P-Type Gan Films Grown By Plasma-Assistedmolecular Beam Epitaxy
Authors: Myoung J. M. , Kim C. , Shim K. H. , Gluschenkov O. , Kim K. , Yoo M. C. 
Published: April 2011

Abstractp-type GaN films were grown on a (0001) sapphire substrate by the plasma-assisted molecular beam epitaxy. A low-contamination, high-power efficiency inductively coupled radio frequency plasma source was used, which was developed at the University of Illinois. Using an MBE system equipped with this plasma source, high-quality p-type GaN films were grown without post-growth treatment. X-ray rocking curve measurements for (0002) diffraction showed a full width at half maximum of less than 7 arcmin. The highest room-temperature hole concentration obtained was 1.4× 1020 cm−3, and for the same sample, the mobility was 2.5 cm2/Vs It is believed that the Mott-Anderson transition occurred in this sample resulting in a metallictype conductivity in the impurity subband. Low-temperature photoluminescence had a blue emission band and no deep-level transitions, indicating the high quality of the grown films. Uniformity of the Mg doping was confirmed by secondary ion mass spectrometry.
Laser Wavelength Dependent Properties of BN Thin Films Deposited by Laser Ablation
Authors: Suda Y. , Nakazono T. , Ebihara K. , Baba K. 
Published: April 2011

AbstractBoron Nitride (BN) thin films are deposited on heated (650 °C ) silicon (100) substrates using Nd:YAG (532 nm) and KrF excimer (248 nm) laser ablation. The laser beam is focused on the hBN targets. The films are grown using a laser repetition rate of 10 Hz atenergy density 3.8 J/cm2. Argon gas is mixed with the reactant nitrogen gas and the total gas pressure in the chamber during deposition is 20 Pa. Auger Electron Spectroscopy shows that the N/B composition ratio depends on the mixture ratio of nitrogen and the relativeemission intensity of B + (345.1 nm). The surface morphology of the films prepared by the 532 nm laser is rough with large particulates, whereas much smoother surfaces with fewer and smaller particulates are obtained with the 248 nm laser. Fourier Transform IR measurement shows that the cBN phase in the films is enhanced by applying the negative RF self-bias voltage ( ˜ 200 V) on the substrate electrode.