bluuebunny/crossref_metadata_2025_split huggingface dataset:
Materials and Device Design with ZnO-Based Diluted Magnetic Semiconductors
Authors: Sato Kazunori , Katayama-Yoshida Hiroshi 
Published: April 2011

ABSTRACTWe propose a materials design to fabricate the transparent and half-metallic ferromagnets in V-, Cr-, Mn+hole, Fe-, Co-, and Ni-doped ZnO based upon ab initio electronic structure calculation. Mn-doped ZnO is anti-ferromagnetic spin glass state, however, it becomes half-metallic ferromagnets upon hole doping. The ferromagnetic state becomes more stable by electron doping in Fe-, Co- or Ni-doped ZnO. From the point of practical applications, it is feasible to realize the half-metallic ferromagnets with high Curie temperature, because n-type ZnO is easily available. We propose the design of new functional devices, such as spin-FET, photo-induced ferromagnets, and spin-injection devices using negative electron affinity in the wide band gap semiconductors.
Relationships Between Microstructure and Reliability in Pzt Mems
Authors: Olson B.W. , Randall L.M. , Richards C.D. , Richards R.F. , Bahr D.F. 
Published: April 2011

ABSTRACTPiezoelectric oxide films, such as lead zirconate titanate (PZT), are now being integrated into MEMS applications. Many PZT derived systems are deposited using a sol-gel process, which can be used in a microelectronics processing route using spin coating as the deposition method. An application of interest for PZT films is in power generation, where a flexing membrane is used to transform mechanical to electrical energy. The current study was undertaken to identify the relationships between the processing, microstructure, and mechanical reliability of these films. Films were deposited onto both monolithic and bulk micromachined platinized silicon wafers using standard sol-gel chemistries, with roughness and grain size tracked using electron and scanning probe microscopy. Mechanical properties were evaluated in a dynamic bulge testing apparatus. Grain size variations in the Pt film between 35 and 125 nm are shown to have little effect on grain size of the subsequent PZT film and the adhesion of the PZT to the Pt film. Only the Pt film with 125 nm grains was shown to undergo any significant interfacial fracture. Fatigue tests suggest film lifetime is primarily limited by the number of pre- existing flaws in the film from processing. Reducing the microcrack density has been shown to produce films and devices that fail at strains of 1.4% and have mechanical fatigue lifetimes in excess of 100 million cycles at strains simulating the operating conditions.
Random Telegraph-like Signals in Ultrathin CMR Films
Authors: Lisauskas A. , Khartsev S. I. , Grishin A. M. 
Published: April 2011

ABSTRACTThe aim of the present paper is to study low frequency (10 Hz - 10 kHz) noise in low dimensional colossal magnetoresistors (epitaxial CMR films). Two contributions in electrical fluctuations were observed: thermal noise, which depends on resistance and temperature, and excess part, which is determined by resistance fluctuations and are mostly related to film microstructure. For films, thicker than the critical thickness, excess noise spectra has 1/fα dependence with α = 1 ± 0.2. In films thinner than the critical one there are random telegraph like signals (TLS) with Lorentzian spectra appear on the background of 1/f noise. Noise spectroscopy reveals the relaxation process in 4.2 nm thick film has thermally activated character with an energy gap of 20 meV at temperatures below 156 K and 78 meV at T > 156 K.
Colossal Temperature Coefficient of Resistivity in Epitaxial Colossal Magnetoresistive La0.67Ca0.33MnO3 Films
Authors: Khartsev S.I. , Grishin A.M. 
Published: April 2011

ABSTRACTEpitaxial La0.67Ca0.33MnO3(LCMO) films have been grown by pulsed laser deposition technique on three single crystal substrates: LaAlO3, SrTiO3, and NdGaO3 having lattice mismatch with LCMO film of + 1.26 %, - 0.9 %, and + 0.18 %. We found the transport colossal magnetoresistive (CMR) properties were improved with the reduction of a film/substrate mismatch. Processing conditions for LCMO film on NdGaO3substrate were optimized as well as post-annealing process was employed to achieve a superior temperature coefficient of resistivity TCR = 35 %K−1 and the magnetoresistance MR = 66 % at 7 kOe. To our knowledge, these are the record CMR parameters achieved so far.
Advances in the Development of Quantum Splitting Phosphors
Authors: Setlur A.A. , Comanzo H.A. , Srivastava A.M. , Beers W.W. , Jia W. , Huang S. , Lu L. , Wang X. , Yen W.M. 
Published: April 2011

ABSTRACTQuantum splitting phosphors (QSPs) are phosphors that could convert VUV radiation into more than one visible photon. These phosphors have the potential to improve the efficacy of current Hg fluorescent lamps and/or Xe lamps by reducing the Stokes shift energy loss after VUV excitation (λexc=185 nm for Hg lamps or 147 nm and 172 nm for Xe lamps provided the emission color of the phosphor matches the eye sensitivity. The current technology in QSPs and their potential limitations will be discussed in this paper. At GE-CRD, we have discovered and developed QSPs that meet the requirements for use in current Hg based fluorescent lamps. The steady state and time resolved optical properties of one of these phosphors, SrAl12O19:Pr3+,Mg2+, has been measured to estimate the maximum quantum efficiency and onset of concentration quenching in this phosphor. The maximum quantum efficiency for SrAl12O19:Pr3+,Mg2+ has been calculated to be ∼125-135% for 185 nm excitation with an upper bound on the Pr3+ doping level of ∼1%.
Enhancement of Photoluminescence from Organic and Inorganic Surface Passivated ZnS Quantum Dots
Authors: El-Khair Hatim Mohamed , Xu Ling , Li Mingha , Ma Yi , Huang Xinfan , Chen Kunji 
Published: April 2011

ABSTRACTZnS quantum dots (QDs) chemically synthesized in PVP stabilizing medium have been coated with Zn(OH)2, SiO2and polystyrene (PS) shells as inorganic and organic passivation agents. to synthesize ZnS/Zn(OH)2, ZnS/SiO2and ZnS/PS QDs. PL properties of inorganically passivated ZnS/Zn(OH)2 and ZnS/SiO2 had reported band edge enhancement of 8-10 times, while organically passivated ZnS/PS QDs exhibit tremendous enhancement of band edge emission as much as 10-15 times,. Therefore inorganic and organic coating can passivate trap states of different energies on the surface of ZnS QDs.
Morphology and Cathodoluminescence of Li-Doped SrTiO3:Pr3+,Ga3+, A Red Phosphor Operating at Low Voltages
Authors: Kim Jin Young , Jeon Duk Young , Kang Seong-Gu , Kang Seung-Youl , Suh Kyung-Soo 
Published: April 2011

ABSTRACTSrTiO3:Pr,Ga phosphor using Li2CO3 as a flux has been investigated as a red phosphor for the application to fluorescent displays operated at low voltage. In SrTiO3:Pr,Ga system, Pr3+can substitute for Sr2+ because the ionic radius of Pr3+almost coincides with that of Sr2+. Previous work, it was found by XRF analysis of SrTiO3:Pr,Ga single crystal that only a small fraction of Pr ions are incorporated in the SrTiO3 lattice. In the present study, the effect of Li addition into SrTiO3:Pr,Ga on the cathodoluminescence (CL) properties was examined at low acceleration voltage. Especially, thanks to the liquid phase of Li2CO3 during the sintering process, doped Li ions act as a lubricant for the efficient incorporation of Pr ions into SrTiO3:Pr,Ga lattice. Furthermore, it is found that the Li addition could enhance the generation of the characteristic emission of Pr-activated SrTiO3phosphors.
Synthesis and luminescence properties of colloidal lanthanide doped YVO4
Authors: Huignard Arnaud , Gacoin Thierry , Chaput Frédéric , Boilot Jean-Pierre , Aschehoug Patrick , Viana Bruno 
Published: April 2011

ABSTRACTAqueous colloidal solutions of well dispersed YVO4:Ln (Ln = Eu, Nd) nanoparticles are synthesized through precipitation reactions at room temperature. In the case of YVO4:Eu, a luminescence quantum yield of 15% is found, which is not as high as in the bulk due to the existence of residual crystalline defects and nonradiative relaxations from the hydroxylated surface. Appropriate hydrothermal annealing and deuteration of the surface allow to rise the yield up to 38%. Incorporation of the nanocrystals into a transparent silica matrix is achieved through preliminary coating of the particles with a functionnalized silicon alkoxide and further dispersion into a sol-gel precursor solution. Such sol-gel materials doped with YVO4:Nd nanocrystals are transparent and exhibit the typical emission at 1.06 μm of the Nd3+ ion.
Nanocrystal Quantum Dots: Building Blocks for Tunable Optical Amplifiers and Lasers
Authors: Hollingsworth Jennifer A. , Mikhailovsky Alexander A. , Malko Anton , Klimov Victor I. , Leatherdale Catherine A. , Eisler Hans –J. , Bawendi Moungi G. 
Published: April 2011

ABSTRACTWe study optical processes relevant to optical amplification and lasing in CdSe nanocrystal quantum dots (NQD). NQDs are freestanding nanoparticles prepared using solution-based organometallic reactions originally developed for the Cd chalcogenides, CdS, CdSe and CdTe [J. Am. Chem. Soc. 115, 8706 (1993)]. We investigate NQDs with diameters ranging from 2 to 8 nm. Due to strong quantum confinement, they exhibit size-dependent spectral tunability over an energy range as wide as several hundred meV. We observe a strong effect of the matrix/solvent on optical gain properties of CdSe NQDs. In most of the commonly used solvents (such as hexane and toluene), gain is suppressed due to strong photoinduced absorption associated with carriers trapped at solvent-related interface states. In contrast, matrix-free close packed NQD films (NQD solids) exhibit large optical gain with a magnitude that is sufficiently high for the optical gain to successfully compete with multiparticle Auger recombination [Science 287, 10117 (2000)]. These films exhibit narrowband stimulated emission at both cryogenic and room temperature, and the emission color is tunable with dot size [Science 290, 314 (2000)]. Moreover, the NQD films can be incorporated into microcavities of different geometries (micro-spheres, wires, tubes) that produce lasing in whispering gallery modes. The facile preparation, chemical flexibility and wide-range spectral tunability due to strong quantum confinement are the key advantages that should motivate research into NQD applications in optical amplifiers and lasers.
Excited State Relaxation Mechanisms in InP colloidal Quantum Dots.
Authors: Rumbles Garry , Selmarten Don , Ellingson Randy E. , Blackburn Jeff , Yu Pingrong , Smith Barton B. , Micic Olga I. , Nozik Arthur J. 
Published: April 2011

ABSTRACTWe report photoluminescence, linear absorption and femto-second transient bleaching spectra for a colloidal solution of indium phosphide (InP) quantum dots at ambient temperatures. The photoluminescence quantum yield is shown to depend not only upon the size of the quantum dots, with larger dots exhibiting higher quantum yields, but also upon the excitation wavelength. At short wavelengths, photoluminescence excitation spectra deviate markedly from the absorption spectra indicating that an efficient non-radiative deactivation pathway becomes prominent at these higher photon energies. We interpret this observation in terms of an inefficient relaxation mechanism between the second excited state and the lowest energy excited state from which the emission emanates. The results are consistent with the existence of a phonon bottleneck.
Chemical mapping of indium rich quantum dots in InGaN/GaN quantum wells
Authors: Sharma N , Cho H K , Lee J Y , Humphreys C J 
Published: April 2011

ABSTRACTIndium clustering in InGaN/GaN multiple quantum wells (MQWs) is believed to be responsible for the high luminescent efficiency of GaN based light emitting diodes. In this paper we show that substantial clustering can be induced by reducing to zero the interruption time between growth of the GaN barrier layer on the InGaN quantum well. Photoluminescence (PL) shows that this has the effect of increasing the luminescence intensity and decreasing the band gap energy (higher indium concentration). The clusters or quantum dots were examined and quantified by energy filtered transmission electron microscopy (EFTEM), which was used to form chemical distribution maps of indium, gallium and nitrogen. In this paper we will show that this technique can accurately calculate the indium concentration and distribution in the quantum wells. The calculations show that InxGa1−xN quantum dots (width = 1.3nm) exhibit an In concentration of up to x = 0.5, which are embedded in a quantum well matrix with x = 0.05.
Optical and Electrical Properties of Cr-SiO Thin Films for Flat Panel Displays
Authors: Wood Richard , Hofstra Peter , Johnson David 
Published: April 2011

ABSTRACTLow temperature fabrication of transparent conducting materials is a key issue in flat panel display production. Though Cr-SiO cermet thin films have predominantly been used as thin film resistors in a variety of microelectronics applications, it is shown in this paper that the material can successfully be used as a transparent to semi-transparent conductor in some applications if the value of the extinction coefficient, k, can be kept low (<0.3). Thus, a detailed study of the interdependence of the resistivity and optical properties of Cr-SiO is presented for the first time within the context of its use in the flat panel display industry. Specifically, Cr-SiO can be employed as part of Luxell's optical interference structure, known as the Black Layer™, US patent 5,049,780, used to increase contrast in TFEL and OLED displays.
Conductance Imaging of the Depletion Region of Biased Silicon PN Junction Device
Authors: Park Jeong Young , Phaneuf R. J. , Williams E. D. 
Published: April 2011

ABSTRACTSimultaneous conductance imaging and constant current mode STM imaging have been used to delineate Si pn junction arrays over a range of reverse bias conditions. Conductance has been obtained by adding a modulation signal to voltages applied in the p and n regions of a model device, and by measuring the modulation signal of the tunneling current with a lock-in amplifier. Both constant current and conductance imaging ofthe electrically different regions (n, p, and depletion zone) show a pronounced dependence on applied pn junction bias. The conductance contrast is mainly due to electrically different behaviors of metal-gap-semiconductor junction which are determined by the tip-induced band bending of the oxide-passivated silicon surface.
Demonstration of the state-of-the-art of formation and characterization of ultra-shallow junctions
Authors: Borden P. , Al-Bayati A. , Madsen J. , Lazik C. , Carey P. , Bechtler L. , Mayur A. 
Published: April 2011

ABSTRACTDoping process windows are becoming very narrow as VLSI technology nodes scale to smaller and smaller dimensions. The time and cost required to develop new doping methods and the desire to re-use equipment will make it likely that current methods will be applied as long as possible. This means that existing process tools will have very tight stability and uniformity requirements, and metrology will be required to drive process control. The paper describes the state-of-the-art of both doping processes involving ion implantation and spike annealing, and new metrology based on Carrier IlluminationTM methods that will be required to implement in-line process control for these processes. CI offers depth resolution on the order of1Å, providing a level of control required to extend existing doping methods. The prospects of new methods such as Laser Thermal Annealing (LTA) are also discussed.
Use of isotopically pure silicon material to estimate silicon diffusivity in silicon dioxide
Authors: Tsoukalas D. , Tsamis C. , Normand P. 
Published: April 2011

ABSTRACTIn this paper we report measurement of the silicon diffusion coefficient in silicon dioxide films using isotopically enriched 28Si silicon dioxide layers. 30Si atoms are introduced in excess in a stoichiometric isotopically pure silicon dioxide layer either by ion implantation or by a predeposition technique and the time evolution of the 30Si concentration profile under various thermal conditions is monitored using SIMS. The estimated diffusivity values are significantly higher than previouslyreported values for Si diffusion within a stoichiometric oxide and closer to reported values for excess Si diffusion within an oxide.
Vacancy and oxygen behavior in carbon highly doped silicon
Authors: Lavéant Pierre , Werner Peter , Engler Norbert , Goesele Ulrich 
Published: April 2011

ABSTRACTCarbon doping of silicon has gained interest since in high concentrations, carbon can reduce oreven suppress undesirable diffusion of the base dopant boron in silicon-based bipolar transistors. This behavior can only be understood in taking into account the silicon point defects i.e. vacancies and self-interstitials. In this work, we observe the oversaturation of vacancies produced by a high carbon concentration duringannealing. Experiments with a vacancy diffusing dopant, Antimony, are shown and prove this effect: in a carbon rich sample, the antimony diffusion is enhanced about 8 times compared to samples with a much lower carbonconcentration. We also investigate the carbon co-precipitation with oxygen. The carbon precipitation, asSiC, is facilitated with a high oxygen concentration. We explain this affinity by an exchange of point defects and a volume compensation. Finally, we show the precipitation of oxygen in relation to the vacancy oversaturation at 900°C.
Ab-Initio Modeling of C-B Interactions In Si
Authors: Liu Chun-Li , Windl Wolfgang , Borucki Len , Lu Shifeng , Liu Xiang-Yang 
Published: April 2011

ABSTRACTWe present the results of ab-initio calculations for the structure and energetics of small boron-carbon (BCI) as well as carbon-carbon (C2I) clusters in Si, a continuum model for the nucleation, growth, and dissolution of the clusters, and experimental investigation by SIMS. The modeling results suggest that these clusters may play a role in controlling B diffusion in Si and SiGe systems and the experimental results seem to support the modeling findings.
Effect of the Ge preamorphisation dose on the thermal evolution of End of Range defects
Authors: Colombeau B. , Cristiano F. , Marrot J-C. , Assayag G. Ben , Claverie A. 
Published: April 2011

ABSTRACTIn this paper, we study the effect of the Ge+ preamorphisation dose on the thermal evolution of End of Range (EOR) defects upon annealing. Amorphisations were carried out by implanting Ge+ at 150 keV to doses ranging from 1×1015 ions/cm2 to 8×1015ions/cm2. Rapid Thermal Annealing (RTA) was performed for various time/temperature combinations in nitrogen ambient. Plan view transmission electron microscopy under specific imaging conditions was used to measure the size distributions and densities of the EOR defects. We found that for a fixed thermal budget, the increase in the Ge ion dose results in an increase in the defect density but has no effect on the defect size distribution. This invariance of the mean size of defects with respect to the initial supersaturation introduced in the matrix is an expected characteristic of a conservative Ostwald ripening mechanism. Moreover, the total number (Nb) of Si interstitial atoms bound to the EOR defects is a monotonically increasing function of the Ge ion dose. Furthermore, we found that Nb is directly proportional to the number of Si atoms in excess of the vacancies found below the a/c interface as calculated by MonteCarlo simulations. This is consistent with the “excess interstitial” model which explains the origin of the EOR defects.
Determining the Ratio of the Precipitated versus Substituted Arsenic by XAFS and SIMS in Heavy Dose Arsenic Implants in Silicon
Authors: Sahiner M. A. , Novak S. W. , Woicik J. C. , Liu J. , Krishnamoorty V. 
Published: April 2011

ABSTRACTDoping silicon with arsenic by ion implantation above the solid solubility level leads to As clusters and/or precipitates in the form of monoclinic SiAs causing electrical deactivation of the dopant. Information on the local structure around the As atom, and the As concentration depth profiles is important for the implantation and annealing process in order to reduce the precipitated As and maximize the electrically activated As. In this study, we determined the local As structure and the precipitated versus substituted As for As implants in CZ (001) Si wafers, with implant energies between 20 keV and 100 keV, and implant doses ranging from 1 × 1015/cm2 to 1 × 1018/cm2. The samples were subjected to different thermal annealing conditions. We used secondary ion mass spectrometry (SIMS) and UT- MARLOWE simulations to determine the region where the As-concentration is above the solid solubility level. By x-ray absorption fine structure spectroscopy (XAFS), we probed the structure of the local environment around As. XAFS being capable of probing the short-range order in crystalline and amorphous materials provides information on the number, distance and chemical identity of the neighbors of the main absorbing atom. Using Fourier analysis, the coordination numbers (N) and the nearest-neighbor distances (R) to As atoms in the first shell were extracted from the XAFS data. When As precipitates as monoclinic SiAs, the nearest-neighbor distances and coordination numbers are ∼2.37 Å and ∼3, as opposed to ∼2.40 Å and ∼4 when As is substitutional. Based on this information, the critical implant dose where the precipitation/clustering of As starts, and the ratio of the substitutional versus cluster/precipitate form As in the samples were determined.
Boron Segregation and Electrical Properties in Polycrystalline SiGeC
Authors: Stewart E. J. , Carroll M. S. , Sturm J.C. 
Published: April 2011

ABSTRACTPreviously, it has been reported that PMOS capacitors with heavily boron-doped polycrystalline SiGeC gates are less susceptible to boron penetration than those with poly Si gates [1]. Boron appears to accumulate in the poly SiGeC layers during anneals, reducing boron outdiffusion from the gate despite high boron levels in the poly SiGeC at the gate/oxide interface. In this abstract, we report clear evidence of strong boron segregation to polycrystalline SiGeC layers from poly Si, with boron concentration in poly SiGeC (Ge=25%, C=1.5%) increasing to four times that of adjacent poly Si layers. A separate experiment confirms that this result is not due to any SIMS artifacts. Electrical measurements of heavily in-situ doped single layer samples show that the conductivity of poly SiGeC is similar to poly Si and remains roughly constant with annealing at 800°C. However, in a two-layer sample where the poly SiGeC is initially lightly doped and subsequently heavily doped by diffusion by from an adjacent poly Si layer, conductivity appears lower than in poly Si.