bluuebunny/crossref_metadata_2025_split huggingface dataset:
Infrared Spectroscopy of Impurities in ZnO Nanoparticles
Authors: Hlaing Oo W. M. , McCluskey M. D. 
Published: June 2019

AbstractSemiconductor nanoparticles have a range of potential applications in electronic, optoelectronic and spintronic devices. Zinc oxide (ZnO), a wide-bandgap semiconductor, has emerged as an important material for such applications. In this work, impurities in ZnO nanoparticles were investigated with infrared (IR) spectroscopy, and the results show the presence of CO2 impurities in ZnO nanoparticles. Isotopic substitution was used to verify the frequency assignment and the results demonstrate conclusively that the impurities originate from the precursors. Isochronal annealing experiments were performed to study the formation and stability of the CO2 molecules. In addition to unintentional CO2 impurities, we intentionally introduced hydrogen into ZnO nanoparticles. Our results show that post-growth annealing in hydrogen dramatically changes IR transmission, reflection and electrical properties of the nanoparticles.
Conductivity Enhancement in Thin Silicon-on-Insulator Layer Embedding Artificial Dislocation Network
Authors: Ishikawa Yasuhiko , Yamauchi Kazuaki , Yamamoto Chihiro , Tabe Michiharu 
Published: June 2019

AbstractA nanometer-scale dislocation network is artificially formed in thin top Si layer of silicon-on-insulator (SOI) structure, and effect of the dislocation network on the transport property is examined from the viewpoint of nanodevice applications. The artificial network of screw dislocations was formed in the Si layer using a wafer bonding of a pair of (001) SOI wafers with a slight misalignment of the in-plane crystalline directions to cause a lattice mismatch. The transmission electron microscopy clearly revealed the formation of dislocation network at the bonding interface with the period less than ∼20 nm. The dislocation network was found to enhance the conductivity in the Si bicrystal layer more than one order of magnitude in comparison with that in the monocrystal layer free from the dislocations. The enhanced conductivity is probably derived from an increased concentration of electrons around the dislocations due to the formation of donor-like gap states.
Silicon Single-Electron Pump and Turnstile: Interplay with Crystalline Imperfections
Authors: Ono Yukinori , Fujiwara Akira , Takahashi Yasuo , Inokawa Hiroshi 
Published: June 2019

AbstractThe single-electron device (SED), which has quantum dot(s), or island(s) in its core, enables the control of electron motion on the level of an elementary charge. The single-electron pump and turnstile are members of the SED family and enable single-electron transfer synchronized with the gate clock. They have the potential for extremely low error rates of electron transfer and are thus expected to be building-block devices for future information processing and electrical metrology. We have been pursuing the fabrication of Si-based SEDs using CMOS technology with the help of electron-beam lithography and have recently demonstrated a Si single-electron pump and turnstile. They are composed of one Si quantum dot and two tiny MOS gates and have dramatically increased the operation temperatures, which opens up the possibility of the practical use of the pump and turnstile.Another path to realizing single-electron transfer, which we will discuss here, might be to use a localized state in the Si bandgap instead of quantum dots. The localized states could in principle be donor/acceptor levels or any other states created by crystalline imperfections. They are free from the problem of the critical size control of the quantum dots, which might lead to a new era of single-electronics in combination with the rapidly developing research field of “dopant engineering”.
Bubbles and Cavities Induced by Rare Gas Implantation in Silicon Oxide
Authors: Ntsoenzok E. , Assaf H. , Ruault M.O. 
Published: June 2019

AbstractIn this pioneering study, we have extended noble-gas implant-induced cavity generation in Si and other semiconductors to a dielectric, viz., SiO2 by implanting a variety of inert gas species. It has been seen that helium and neon do not induce bubbles/cavities in SiO2, regardless of implantation parameters and nature of the sample. Krypton and xenon implantation however result in bubbles/cavities formation in the oxide layer. In the case of Xe a minimum threshold dose of about 1016 cm-2 is needed for their formation. Characterization by cross-section transmission electron microscopy (XTEM) and Rutherford backscattering spectrometry (RBS) showed that bubbles/cavities remain even after a 1100°C anneal, while Xe strongly desorbs out at that temperature. C-V measurements reveal that the effective dielectric constant K is reduced from 3.9 SiO2 for bulk SiO2 to < 2.6, thus making this technique very attractive for low-k applications in Si technology.
A New Post Annealing Method for AlGaN/GaN Heterostructure Field-Effect Transistors Employing XeCl Excimer Laser Pulses
Authors: Ha Min-Woo , Lee Seung-Chul , Park Joong-Hyun , Seo Kwang-Seok , Han Min-Koo 
Published: June 2019

AbstractA new post annealing method employing excimer laser pulses is proposed to improve the transfer characteristics and the breakdown voltage of the unpassivated AlGaN/GaN heterostructure field-effect transistor (HFET) and the passivated one. The XeCl excimer laser pulses with wavelength of 308 nm anneal the AlGaN/GaN HFET after the Schottky gate metallization. The interface defects between the Schottky gate metal and a GaN layer is decreased by the lateral heat diffusion of the laser pulses. Our experimental results show that the drain current and the maximum transconductance of the unpassivated AlGaN/GaN HFET after laser pulses annealing are 496 mA/mm and 134 mS/mm while a virgin device shows 434 mA/mm and 113 mS/mm, respectively. The proposed method anneals effectively the SiO2 passivated AlGaN/GaN HFET and the leakage current of the passivated device is decreased from 483 nA to 29 nA.
Hydrogen Diffusion in Boron-Doped Hydrogenated Amorphous Silicon Films: Crystallization and Induced Structural Changes
Authors: Kail F. , Hadjadj A. , Cabarrocas P. Roca i 
Published: June 2019

AbstractWe have studied the evolution of the structure of boron-doped hydrogenated amorphous silicon films exposed to a hydrogen plasma. From the early stages of exposure, hydrogen diffuses and forms a thick H-rich subsurface. At longer times, hydrogen plasma leads to the formation of a microcrystalline layer via chemical transport without crystallization of the initial layer. We observe that the hydrogen content increases in the films during a plasma exposure and once the microcrystalline layer is formed hydrogen diffuses out of the sample accompanied with a decrease in the boron content. This effect can be attributed to the electric field developed within the heterojunction a-Si:H/μc-Si:H that drives the positively charged hydrogen atoms in the boron-doped layer towards the μc-Si:H layer.
Fabrication of Silicon Carbide PIN Diodes by Laser Doping and Planar Edge Termination by Laser Metallization
Authors: Tian Z. , Quick N.R. , Kar A. 
Published: June 2019

AbstractSilicon carbide PIN diodes have been fabricated using a direct write laser doping and metallization technique. Trimethyaluminum (TMA) and nitrogen are precursors used to laser dope p-type and n-type regions, respectively, and μ4.3 mm p-type doped junction and 4 mm ntype doped junction are fabricated in semi-insulating 6H-SiC wafers. Rutherford backscattering studies show that no amorphization occurred during the laser doping process. A planar edge termination is fabricated by laser metallization in argon ambient to form a high resistivity layer. With this termination, the leakage current of the PIN diodes can be suppressed effectively compared to that of diodes without edge termination. The performance of the diodes can also be tailored by shrinking the active area of the diode and by conventional annealing.
Photoelectron Emission Technique for the Surface Analysis of Silicon Wafer Covered with Oxide Film
Authors: Sakurai Takao , Momose Yoshihiro , Kudou Masanori , Nakayama Keiji 
Published: June 2019

AbstractA new analysis method using the photoelectron emission yield spectra near threshold has been developed to characterize solid surfaces exposed to ambient air. The application of the analysis method to the yield spectra for a Si (100) wafer surface covered with a native oxide film revealed that three emission peaks are cumulated on the basic yield spectrum line for the silicon. It was indicated that these peaks have a Gaussian-shaped density distribution and the energy levels are located at 5.37, 5.68, and 6.02 eV below the vacuum level, respectively.
Identification and Characterization of Submicron Defects for Semiconductor Processing
Authors: Liu Wei , Fausz Aime , Svoboda John , Butcher Brian , Williams Rick , Schauer Steve 
Published: June 2019

AbstractAuger Electron Spectroscopy (AES) is one of the few techniques that has surface sensitivity and small analysis volume to make it the ideal analytical technique for the compositional characterization of submicron defects. However, the integration of defect inspections at only a few processing steps during device fabrication results in the detection of many buried defects. In order to identify these defects, it is necessary to determine their composition. Combined with Focused Ion Beam (FIB) technique to expose the cross section of the buried defect, Auger analysis provides accurate identification of buried defects that are critical for quickly ramping to higher yields and recovering from yield excursions. This paper reports two examples of the use of AES combined with FIB to diagnose processing problems.
Optical and Electrical Characterization of Quantum Dot Infrared Photodetector Structure Treated with Hydrogen-Plasma
Authors: Nam H.D. , Song J.D. , Choi W.J. , Lee J.I. , Yang H.S. 
Published: June 2019

AbstractWe have carried out hydrogen-plasma (H-plasma) treatments on a quantum dot infrared photodetector (QDIP) structure, with a 5-stacked InAs dots in an InGaAs well structure and a Al0.3Ga0.7As/GaAs superlattice barrier. The sample structures were grown by molecular beam epitaxy. The H-plasma treatment has been carried out at 150 °C for 3 min – 40 min with 40 sccm of H2 gas flow rate and 10 W of RF power. After H-plasma treatment, photoluminescence (PL) intensities of the samples were slightly reduced compared to that of as-grown sample, without any changes in their PL peak position. The dark currents of H-plasma treated samples were much smaller by many orders of magnitudes than that for as-grown sample. The sample exposed to Hplasma for 10 min showed the lowest dark current, enabling the observation of photocurrent with a wide spectrum between 3 – 12 μim at 11 K.
Blistering and Splitting in Hydrogen-implanted Silicon
Authors: Ntsoenzok E. , Assaf H. , Ashok S. 
Published: June 2019

AbstractWe implanted hydrogen in silicon with energies ranging from 500 keV to 2 MeV for implant depths varying from 6.1 to 48.4 μm according to TRIM (transport of ions in matter) 2003. After implantation, a 600 °C thermal annealing was applied to all samples. It is found that for depths lower than 9 μm there is no lift-off of a free-standing silicon layer; only a blistering phenomenon is seen. Increase in the implanted dose or thermal budget does not improve the situation. However, for depths ≥9 μm (9 - 50 μm in this study) thermal annealing results in effective detachment of ultra-thin free-standing layers. This technique hence provides high quality thin Si layers for semiconductor technology.
Erbium Doped Silicon Single- and Multilayer Structures for LED and Laser Applications
Authors: Krasilnik Zakhary F. , Andreev Boris A. , Gregorkiewicz Tom , Jantsch Wolfgang , Klik Mark A.J. , Kryzhkov Denis I. , Krasilnikova Ludmila V. , Kuznetsov Viktor P. , Przybylinska Hanka , Remizov Dmitry Yu. , Shengurov Vladimir G. , Shmagin Viacheslav B. , Stepikhova Margarita V. , Timoshenko Victor Yu. , Vinh Nguyen Q. , Yablonskiy Artem N. , Zhigunov Denis M. 
Published: June 2019

AbstractThe paper is a brief retrospective review of our contribution to the Si:Er problem in the last decade. It contains a description of the experimental facilities, results of the light emitting media (Si:Er and Si1-xGex:Er) research and device applications.
GaN:Eu Interrupted Growth Epitaxy (IGE): Thin Film Growth and Electroluminescent Devices
Authors: Munasinghe Chanaka , Steckl Andrew , Nyein Ei Ei , Hömmerich Uwe , Peng Hongying , Everitt Henry , Fleischman Zack , Dierolf Volkmar , Zavada John 
Published: June 2019

AbstractThe GaN:RE phosphor development plays a major role in the GaN:RE AC thick dielectric electroluminescent (TDEL) device optimization. In this paper we report on EL devices fabricated using Eu-doped GaN red phosphors films grown by interrupted growth epitaxy (IGE). IGE consists of a sequence of ON/OFF cycles of the Ga and Eu beams, while the N2 plasma is kept constant during the entire growth time. IGE growth of GaN:Eu resulted in significant enhancement in the Eu emission intensity based primarily at 620.5nm. The increase in the material crystallinity observed with the IGE phosphors appears to be the dominant cause of the emission enhancement. Thick dielectric EL devices fabricated on glass substrates using IGE-grown GaN:Eu have resulted in luminance of ∼1000 cd/m2.
Study of Optical Gain in Thick GaN Epilayers by Variable Stripe Length Technique
Authors: Tamulaitis G. , Mickevic J. , Shur M. , Fareed Q. , Gaska R. 
Published: June 2019

AbstractWe report on the gain study in high-quality thick GaN layers using the Variable Stripe Length (VSL) technique. The layers were grown by Migration Enhanced Metal Organic Chemical Vapor Deposition (MEMOCVDTM). The amplification of light was investigated for the propagation directions along the layer surface (perpendicular to the c-axis of the crystal) and perpendicular to the layer (along the c-axis) for the layers with thicknesses up to 11 νm. By fitting the experimental stripe length dependence of the edge luminescence with one-dimensional description of light amplification in medium with positive gain, peak gain coefficients of up to 7300 cm-1 were estimated in GaN at the excitation power density of 2 MW/cm2. We discuss limitations of the VSL technique due to the assumption of one-dimensional light propagation and strong influence of gain saturation in a high-gain medium. The contribution of new gain modes after saturation of the highest-gain modes was observed. The optical gains in GaN samples with different carrier lifetimes (obtained using time-resolved photoluminescence and light-induced transient grating techniques) were compared.
Synthesis and Unprecedented Electro-Optic Response Properties of Twisted π-System Chromophores
Authors: Kang Hu , Facchetti Antonio , Jiang Hua , Zhu Peiwang , Marks Tobin J. 
Published: June 2019

AbstractA series of unconventional twisted intramolecular charge-transfer (TICT) chromophores was designed and synthesized. These chromophores exhibit ultra-large first hyperpolarizabilities. The structural characteristic that promotes this unusual nonlinear optical response is a sterochemically enforced reduction of the D- π-A conjugation that enforces zwitterionic behavior in the ground state and provides a low-energy, large-oscillator strength intramolecular excitation feature. The consequence is that molecules with relatively small numbers of π-electrons exhibit responses far larger than those of traditional planar π-conjugated chromophores. At 1907 nm, non-resonant νβ values as high as -466,000 × 10-48 esu are observed.
Highly Fluorinated Hybrid Glasses doped with (Erbium-ions/CdSe Nanoparticles) Designed for Advanced Laser Amplifiers
Authors: Choi Kyung M. , Rogers John A. 
Published: June 2019

AbstractBridged polysilsesquioxanes were synthesized by modifying the Si-O-Si polymeric network to produce highly nanoporous glasses for facile and uniform doping of nanoparticles. By taking advantages of void volumes created through the molecular modification technique, we designed and synthesized hexylene- and fluoroalkylenebridged polysilsesquioxanes doped with both Er+3 ions/CdSe nanoparticles for amplifier applications. Significant enhancement in fluorescence intensity at 1540 nm has been observed from the fluoroalkylene-bridged glass. Analysis by nuclear magnetic resonance (NMR) indicates a dramatically enhanced degree of condensation and a low level of hydroxyl environment in the fluoroalkylene-bridged hosts. The presence of CdSe nanoparticles, by virtue of their low phonon energy, also appears to significantly influence the nature of the surrounding photoluminescence environment of Er+3 ions in those organically modified hosts, resulting in the increased photoluminescence intensity.
Fabrication of Er3+/Pr3+ Co-doped Soda-lime Glass Thin Films Using RF Magnetron Sputtering Method and Optical Property Characterization
Authors: Shin Sang-Hoon , Kim Sung-Dae , Moon Jong-Ha , Kim Jin Hyeok 
Published: June 2019

AbstractEr3+/Pr3+ co-doped soda-lime glass thin films have been fabricated using RF magnetron sputtering method and their structural and optical properties have been studied. Deposition rate, crystallinity, and composition of glass thin films were investigated by scanning electron microscopy, transmission electron microscopy, and electron probe micro area analysis. Refractive index, birefringence and binding characteristics have been investigated using a prism coupler and x-ray photoelectron spectroscopy. Er3+/Pr3+ co-doped soda lime glass thin films were prepared by changing substrate temperature (room temp.∼550 ), RF power (90W∼150W), and Ar/O2 gas flow ratio at processing pressure of 4mTorr. Glass thin films could be obtained at the optimized processing condition at 350, RF power (130W), and gas flow (Ar:O2=40:0) with maximum deposition rate of 1.6νm/h. Refractive index increased from 1.5614 to 1.5838 and birefringence increased from 0.000154 to 0.000552 as the content of Pr3+ increased. Binding energy of Pr3d increased as the content of Pr3+ increased.
Luminescence of Rare Earth Doped Si/ZrO2 Co-Sputtered Films
Authors: Rozo C. , Fonseca L. F. , Resto O. , Weisz S. Z. 
Published: June 2019

AbstractEr3+, Nd3+ and Tm3+ doped Si/ZrO2 thin films have been prepared by rf co-sputtering. The films are 5 inches long and divided into 50 sections or positions, labeled from P1 to P50. The target configuration is such that the main target is ZrO2 (181.46 cm2), the rare earth (RE) oxide pellet (1.43 cm2) is placed on the main target below the middle of section of the film and the Si chip (6.67 cm2 or 6.00 cm2) is placed on the main target below one end of the film (P40 to P50). The films were annealed to 700°C. The Er3+4I13/2→4I15/2 emission was detected but no 4I13/2→4I15/2 emission was detected. The 4I13/2→4I15/2 emission shows a narrow peak at 1527 nm (FWHM = 6.5 nm for P20) with two weaker side bands from 1430 nm to 1500 nm and from 1550 nm to 1600 nm. The Nd3+4F3/2→4I9/2, 4F3/2→4I11/2, and 4F3/2→4I13/2 emissions were detected being the 4F3/2→4I11/2 peaked at 1065 nm (FWHM = 39.5 nm for P30) the strongest. The 4F3/2→4I9/2 emission is relatively weak, less than one-fourth the peak intensity of the 4F3/2→4I1/2 emission but is broad (FWHM = 92 nm for P30). No Er3+4I13/2→4I15/2 emission or Nd3+4F3/2 emissions were detected for the Si rich ends of the respective films, being the emission stronger from the Si poor end of the film towards the middle of the film. The maximum Er3+4I13/2→4I15/2 emission is for P20 and the maximum peak intensity for the Nd3+4F3/2→4I11/2 emission is for P30. The excitation wavelength dependence behavior for the Nd3+4F3/2→4I11/2 emission is that typical of energy transfer from the Si nanoparticles to the emitting Nd3+ ions. The excitation wavelength behavior for the Er3+4I13/2→4I13/2 emission reflects a mix of energy transfer from the Si nanoparticles and strong absorption for excitation wavelengths of 488.0 nm and 514.5 nm. The Tm3+ doped Si/ZrO2 thin film does not exhibit infrared (IR) PL from the 3H4 emission or the 3F4→3H6 emission. The intense band from 500 nm to 800 nm observed for all of the RE doped Si/ZrO2 films, due to defects in ZrO2, barely permits the detection of the Tm3+3H4→3H6 emission which is best observed for P35.
Erbium-doped Amorphous- Si-C-O Matrix (a-SiCxOy:Er) - A Novel Silicon-based Material for Near-infrared Optoelectronic Applications
Authors: Gallis Spyros , Huang Mengbing , Nikas Vasileios , Efstathiadis Harry , Eisenbraun Eric , Kaloyeros Alain E. , Nyein Ei Ei , Hommerich Uwe 
Published: June 2019

AbstractWe have synthesized amorphous- SiCxOy (a-SiCxOy) (x, y: 0 - 1.65) materials via thermal chemical vapor deposition (TCVD) at 800°C using a single source oligomer, 2,4,6-trimethyl-2,4,6-trisila-heptane (C7H22Si3) and ultra-high purity oxygen (O2). The Er-doped SiCxOy materials exhibited a strong room-temperature photoluminescence (PL) at ∼1540 nm at an excitation wavelength of 496.5 nm. Furthermore, the infrared PL intensity was found to be highly dependent on the compositions of carbon and oxygen, with the maximum PL intensity obtained for an Er-doped SiC0.50O1.00 thin film, which exhibited a ∼20-times enhancement in the PL intensity as opposed to the Er-doped SiO2 control samples.The PL intensity decreased significantly as the matrix evolves into either the SiC-like or SiO2-like material. Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS) were used to characterize the local elemental electronic environment in a-SiCxOy. Our work indicates a strong correlation between the emission of Er luminescence and the formation of Si-C-O bonding in materials.
Nanocrystalline Rare Earth-doped Gallium Nitride Phosphor Powders
Authors: Hirata G.A. , Tao J. , Chen P. , Mishra K.C. , McKittrick J. 
Published: June 2019

AbstractWe report on the fabrication and luminescent properties of rare earth-doped gallium nitride (GaN) phosphor powders. Single phase GaN and GaN:RE3+ powders were prepared by using a novel chemical route.In this work a new method for the synthesis of high purity, single phase doped GaN powders is reported. (Ga1-xREx)N powders are obtained by dissolving metal nitrates (Ga(NO3)3, (RE(NO3)3) in deionized water and an organic fuel (hydrazine) in order to form a gallium/RE amorphous/nanocrystalline powder. The RE-oxide powders are then reacted with heated ammonia at different temperatures and processing times producing GaN:RE phosphors. X-ray diffraction analysis showed that single phase GaN powders are formed. Preliminary results show (Ga0.95Eu0.05)N powders are luminescent, with the main emission occurring at 611 nm which is due to the 5Do→7F2 transitions in Eu3+. High-purity GaN powders are obtained according to Xray photoelectron spectroscopy (XPS) chemical analysis. Low-temperature cathodoluminescence and photoluminescence measurements indicate that the emission at λ=611 nm is originated from energy transfer from the host to the rare earth ion and to a direct excitation to the Eu3+ electronic levels.This method can be used to obtain red-luminescence GaN:Eu3+ and other rare earth (e.g. Er, Tb, Tm)-doped GaN powders to produce green and blue luminescence as well.