bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metastability of Luminescent Porous Silicon
Authors: Mtyazaki S. , Sakamoto K. , Shiba K. , Hirose M. 
Published: March 2011

ABSTRACTPhotoluminescence from l–3μm thick porous Si layers prepared by anodization of p-type c-Si wafers and subsequent chemical etching exhibits an anomalous temperature dependence and light-induced degradation. The luminescence intensity is almost quenched at temperatures below 30K and recovered by laser irradiation at 48K. This quenching phenomenon is not observed for PS thicker than 10μm. The luminescence fatigue is partially recovered by annealing at 150°C for 5min during which no further oxidation takes place. These observations are interpreted in terms of the structural metastability of hydrogen-terminated porous Si.
Properties of Porous Silicon with Photoluminescence Enhanced by a Remote-Plasma Treatment
Authors: Xiao Y. , Heben M. J. , Pankove J. I. , Tsuo Y. S. 
Published: March 2011

ABSTRACTWe have developed remote-plasma and argon-ion laser-illumination treatments that enhance and stabilize the photoluminescent emission from porous Si (PS) that was electrochemically etched and thermally annealed. Infrared absorption spectroscopy revealed that the bonded oxygen content in the film was increased and the density of surface silicon dihydride bonds was reduced by these processing steps. The photoluminescence (PL) intensity of the treated films was initially about 15 times higher than that of the as—etched films, and increased further with the time of laser irradiation in air until a steady—state intensity was reached. The emission from the treated samples increases with decreasing temperature to a maximum intensity at about 100 K. Below 100 K, the photoluminescence intensity of the treated PS samples remains constant with decreasing temperature down to 7.7 K, whereas the as—etched samples, as well as siloxene, show a rapid decrease in photoluminescence intensity with decreasing temperature in this temperature range. Electron spin resonance data show that dangling bond densities in annealed PS films are reduced by the remote-plasma treatment.
Optical Studies of Electroluminescent Structures from Porous Silicon
Authors: Harvey J. F. , Lux R. A. , Morton D. C. , McLane G. F. , Tsu R. 
Published: March 2011

ABSTRACTTwo components of the electroluminescence (EL) from porous silicon light emitting diode (LED) devices have been observed. A slower component and a faster component have been identified. The slower component has a spectral peak shifted to the red from the corresponding photoluminescence (PL) spectrum. The faster component has a spectral peak well in the infrared (IR). Optical and electrical measurements of these two components are discussed. The temperature dependence of the two EL components are presented and contrasted. Our measurements demonstrate that the two EL components and the PL result from recombination in different parts of the porous silicon structure. As the temperature is reduced below room temperature the slower EL exhibits a decrease in intensity at relatively high temperatures, suggesting a freeze out of electrical carriers due to quantum confinement, resulting in a much reduced electrical excitation of the EL.
Study on the Photoconductive Effect from a P/N Junction Structure Incorporated with Porous Silicon
Authors: Yeh C. C. , Hsu Klaus Y.J. , Chen P. C. , Hwang H. L. 
Published: March 2011

ABSTRACTWe utilized the conventional planar fabrication technique and the electrochemical etching method to prepare porous Si layers in the p-type region of a p/n junction, which could make the study on the transverse transport property of this material possible. The junctions were fabricated by low energy ion-implantation, with porous Si formed perpendicular to the junction and between two metal contacts. This structure confines currents to the direction parallel to the surface. Distinct features on current-voltage (I-V) curves has been observed.
Photovoltaic Device Applications of Porous Silicon
Authors: Tsuo Y. S. , Heben M. J. , Wu X. , Xiao Y. , Moore C. A. , Verlinden P. , Deb S. K. 
Published: March 2011

ABSTRACTWe report on the results of our investigation of using porous Si to enhance the performance of crystalline silicon photovoltaic solar cells. Possible approaches include using the porous Si for (1) surface texturing to enhance light trapping, (2) front or back surface fields because of its wider bandgap, and (3) photon color conversion of blue light to longer wavelengths that have higher quantum efficiency in a Si solar cell. In our surface texturing study, a porous-Si-covered single-crystal Si wafer showed an integrated reflectance of only 1.4% at 500-nm wavelength compared to about 40% for a polished Si surface. For our solar cell study, we used a point-contact cell structure with diffused p+ and n+ point contacts on the back of the cell. This cell structure allows us to form the porous Si on the front surface after both the junction formation and the evaporation and alloying of metal contacts.
Theory of Electronic, Optical and Transport Properties in Silicon Quantum Wires
Authors: Sanders G. D. , Stanton C. J. , Chang Y. C. 
Published: March 2011

ABSTRACTRecent observation of efficient luminescence in porous silicon has stimulated interest in the electronic and optical properties of Si quantum wires [1,2,3]. If silicon becomes a material suitable for optical applications, techniques for fabricating silicon wires reliably and uniformly will be needed. Once this is achieved, there will be interest not only in optical properties of silicon wires but also transport properties. For instance, to determine the properties of a hypothetical Si LED, one needs to know about both transport and optical properties.In this paper, we present theoretical studies of electronic, optical and transpon properties of silicon quantum wires ranging in size from 7.7Ä to 31Ä. The electronic and optical properties are treated in an empirical tight-binding approach with excitonic effects included in the effective mass approximation. Carrier transport is treated in a Boltzmann transport framework with nonpolar deformation potential acoustic phonon scattering being the dominant scattering mechanism.
The Physics of Plasma Deposition of Microcrystalline Silicon
Authors: Drevillon B. , Solomon I. , Fang M. 
Published: March 2011

ABSTRACTThe growth of microcrystalline silicon (μc-Si), deposited by a succession of silane and hydrogen plasmas, is investigated in situ by ellipsometry in the visible and near UV-range. It is found that the amorphous tissue is more affected by the hydrogen etching than the crystallites. The model of “selective etching” emerges from these measurements. Although this model is compatible with the “partial chemical equilibrium” of Vep̌ek, it is somewhat more general and explains the porous nature of the (μc-Si) as well as the many atomic layers deposition-etching sequences.
Xps Studies of Hydrogen and Oxygen Bondinguy Configurations in Hydrogenated Microcrystalline Silicon Materials Produced by Neutron Irradiation
Authors: Koo Y. C. , Weatherly G. C. , Sodhi R. , Thorpet S. J. , Austt K. T. 
Published: March 2011

ABSTRACTThe bonding of Si atoms in μc-Si:H thin films has been investigated using X-ray photoelectron spectroscopy (XPS) in conjunction with infra-red spectroscopy (IR), secondary ion mass spectroscopy (SIMS) and analytical electron microscopy (TEM/EDX/EELS) data. By using a-Si:H and single crystal silicon as reference samples, structural and hydrogen effects could be assessed, since both a-Si:H and μc-Si:H have a similar concentration of hydrogen based on the N15 hydrogen profiling data, but different structures. On the other hand, single crystal silicon and μc-Si:H both have a diamond cubic structure based on electron diffraction data, but single crystal silicon contains little or no hydrogen except adsorbed at the surface. Based on the XPS and IR data, charge transfer of the Si2p core level towards a deep lying level was observed in the μc-Si:H material. IR measurements snowed a large amount of hydrogen was located in the grain boundaries. The charge transfer is mainly due to a change in the hydrogen bonding configuration. A well bonded oxide is formed in the μc-Si:H material near the surface with an almost complete absence of the Si3+ intermediate oxide state. The presence of a large amount of hydrogen (25 at.%) even at a high volume fraction (70%) of μc-phase may limit the oxidation and promote better oxide formation. The variation of the quality of the oxide/μc interface could be a possible explanation for the different photoluminescence observed by various groups for porous μc-Si material.
Enhanced Conductivity in n-Type Microcrystalline Silicon
Authors: Dlrani E. A. T. , de Andrade A. M. , Pereyra I. 
Published: March 2011

ABSTRACTPhosphorus doped μc-Sl:H films have been prepared in a PECVD system from SiH4 + PH3 + H2 gaseous mixtures. The films are obtained as a result of the competition between two simultaneously occuring processes: a deposition one and an etching one due to the high concentration of hydrogen in the plasma. This competition process favours the growth of films with crystalline structure.Highly conductive μc-Si:H layers, in the range of 20 ∼ 30 S.cm-1, were obtained for samples in the range of 70 to 85 nm thick. From Raman Dispersion Spectroscopy and X-Ray Diffraction measurements, evidences of the dominant role of the crystalline phase in the charge transport mechanisms are shown.Through Infrared Spectroscopy measurements it was possible to obtain the concentration of the SiHn groups on the μc-Si:H n+ structure and to Infer their role on the electrical properties of the films.
A new thin film Growth/Regrowth Process Design and Experimental Comparisons with Molecular Dynamic Analyses
Authors: Okada Takako K. , Kambayashi Shigeru , Yabuki Moto , Tsunashima Yoshitaka , Mirata Yuichi , Onga Shinji 
Published: March 2011

ABSTRACTA new concept of thin film growth/regrowth process design taking atomic motions into account using molecular dynamics is proposed. In the system, a modified many-body Tersoff-type interatomic potential for silicon has been adopted. The mathematical derivation of higher order derivatives was rigorously treated. Among many applications, the solid phase growth process was studied. It has been found from simulation studies that the solid phase growth of crystalline silicon proceeded along the [110] direction layer by layer. Furthermore, it has been obtained that all the atoms are activated in an extremely thin amorphous silicon film. Based on simulated results, an experiment using an extremely thin amorphous silicon film was carried out. It has been found that the perfect spherical silicon crystals with a uniform size and spacing can be grown from a thin amorphous silicon film.
Layered Poly/Amorphous Silicon Deposition Process for Improved Silicide Integrity
Authors: Roy P. K. , Nanda A. K. , Taylor J. A. 
Published: March 2011

ABSTRACTThis work describes an elegant way to control suicide integrity and the quality of the silicide/polySi or amorphous (α) Si interface by a multilayered deposition process. Structurally superior polySi/or-Si layer resulting from this process allows one to reduce the stack height of the polySi/α-Si layer without compromising suicide integrity and silicide/Si interfacial qualities.Impact of layering during polySi/α-Si deposition on the suicided structure were evaluated from XRD, RBS, cross-sectional TEM, sheet resistance, and SIMS analysis.
High Substrate Temperature (420 °C) Excimer Laser Crystallization of Hydrogenated Amorphous Silicon
Authors: Carluccio R. , Pecora A. , Fortunato G. , Stoemenos J. , Economou N. 
Published: March 2011

ABSTRACTExcimer laser crystallization of hydrogenated amorphous silicon has been investigated as a function of substrate temperature. At low substrate temperatures hydrogen out-diffusion strongly influences the film morphology, while at 420 °C homogeneous recrystallized films are obtained, as a result of the reduced solidification velocity. This process has been successfully tested by fabricating with the recrystalllized material thin-film transistors according to the bottom-gate configuration.
Control of Polysilicon Emitter Bipolar Transistor Characteristics by Rapid Thermal or Furnace Anneal of the Polysilicon/Silicon Interface
Authors: Bhattacharya S. , Lobo M. , Jung L. , Banerjee S. , Reuss R. , Batra S. , Park K. , Hu G. 
Published: March 2011

ABSTRACTIn this paper we report on the ability of rapid thermal annealing (1050C, 45s) and furnace annealing (900C, 30min) to partially break up the interfacial oxide in bipolar transistors with different oxide thicknesses at the polysilicon/silicon interface. We have obtained the different oxide thicknesses either by performing different ex situ cleans (RCA clean or RCA clean + HF dip) before Low Pressure Chemical Vapor Deposition (LPCVD) of polysilicon, or by using a cluster tool for polysilicon deposition with the ability to perform an in situ clean and then allowing the growth of different oxide thicknesses at the interface prior to polysilicon deposition. For the in situ cleaned devices, it is observed that after the interface anneal, the current gain increases with increasing oxide thicknesses, but with little penalty in terms of higher emitter resistance, Re. This indicates that by controllably increasing the interfacial oxide thickness and by subsequent annealing to partially break up the interfacial oxide, higher current gains can be obtained with little sacrifice in terms of higher Re.
I-V Characteristics and Interface Properties of Al-Si(P) Contacts by the Krf Excimer Laser Induced Recrystallization
Authors: Sohn K. , Lee H. , Hensley D. A. 
Published: March 2011

ABSTRACTAl was deposited on the both sides of p-type Si by the sputtering, and the pulsed KrF excimer laser was irradiated on the one side and both sides of Al dot contacts. Due to the thin-high doping recrystallized layer, the transitions from the Schottky diodes to the ohmic contacts via backward diodes were observed in I-V measurement. Good N-shape negative resistances and notches were observed in the diodes, and ohmic contacts. Possible interpretations of the orgin of these phenomena are discussed. And, the simple model of the effective barrier height reduction under the thermionic field emission was developed using WKB approximation, and tunneling theory. By the depth Auger analysis, Al, and Si profiles near Al-Si interface after the laser irradiation were observed.
A Selective Growth of GaAs Microcrystals Grown on Se-Terminated GaAlAs Surface for the Quantum well Box Structure
Authors: Chikyow Toyohiro , Koguchi Nobuyuki 
Published: March 2011

ABSTRACTA selective growth of GaAs microcrystals was demonstrated on a Se-terminated GaAlAs surface. Ga molecules were supplied to the Se-terminated GaAlAs surface at first. The surface consisted of Ga droplets and bared Se-terminated GaAlAs surface. After the following As molecule supply to the surface, a selective GaAs microcrystal growth from Ga droplets was observed. The cross sectional investigations by the high resolution electron microscope revealed epitaxial growth of GaAs microcrystals with (111) facets and a possibility of (GaAl)2Se3, layer formation at the GaAs/Se-terminated GaAlAs interface.
Microcavity Effects in The Luminescence of GaAs Microcrystals
Authors: Juen S. , Lamprecht K. F. , Rodrigues R. , Höpfel R. A. 
Published: March 2011

ABSTRACTExperimental photoluminescence spectra of GaAs microcrystals show pronounced variations compared to the luminescence of bulk GaAs. The observed spectra are explained by spectral enhancement and inhibition of spontaneous emission in a three-dimensional optical resonator formed by a dielectrically confined semiconductor microcrystal. The crystals were produced by pulverization of bulk GaAs, size-separated by sedimentation techniques, and characterized by transmission electron microscopy, electron diffraction and x-ray diffraction.
Investigation of Misfit Dislocation Configurations in Mbe-Grown InGaAs Layers on Misaligned GaAs (001) Substrates
Authors: Werner P. , Zakharov N. D. , Chen Y. , Liliental-Weber Z. , Washburn J. , Klem J. F. , Tsao J. Y. 
Published: March 2011

ABSTRACTThe configurations of misfit dislocations in In0.2Ga0.8As/GaAs(001) hetero structures grown on slightly misoriented substrates was investigated by transmission electron microscopy (TEM). Layers 6 nm, 20 nm and 40 nm thick were grown by MBE. The substrate was tilted in [110], [110], [120], [210] and [010] directions at angles between 0° and 10°. Only in the 40 nm thick layers networks of 60° and 90° dislocations were formed. Misfit dislocations were found at the interface in <110> directions. In the substrate tilting range between 0° and 4° the changes in dislocation density can be explained by the differentcharacter of α and β dislocations. For a substrate tilting above 6° the different dislocation sets show an increased anisotropy. The misfit dislocations at the interface were decorated by In atoms. The influence of three-dimensional crystal growth on increasing surface roughness is discussed.
Preparation and Characterization of Group 12 Thiolate Complexes and Evaluation of Their Potential as Precursors for II-VI Semiconductors
Authors: Rees William S. , Kräutern Gertrud , Goedken Virgil L. 
Published: March 2011

ABSTRACTWe have prepared compounds having the general formula M(SR)2 (M = Zn, Cd; R = i-Pr, t-Bu, Bz) and Hg(SR)CI (R = i-Pr, Bz) and investigated their use as potential sources in the preparation of metal sulfides from molecular precursors. Selected examples of the prepared compounds have been studied by single crystal x-ray diffraction. Decomposition has been carried out both in the solid state and by heating a suspension of a metal thiolate in a high boiling hydrocarbon. The decomposition products have been studied by GC/MS (liquids) and XRD (solids).
Stress Compensation Techniques in Thin Layers Applied to Silicon Micromachining
Authors: Lang W. , Mük G. , Rose E. , Bausells J. , Kühl K. , Moldovan N. , Suski J. 
Published: March 2011

ABSTRACTStress in thin films is one of the mayor technological problems of silicon micromachining. Therefore stress reduction by a compensation method increases the technological use of a material. Three methods to obtain stress free films are investigated:1. Stress in SiO2 and Si3N4 can be compensated by ion implantation.2. Sandwich layers of SiO2 and Si3N4 can be made internally stress compensated by variation of the thickness ratio.3. Polysilicon is stress reduced by appropriate doping and annealing.The film stress is evaluated by the measurement of the bending of the substrate. Examples of processed membranes, bridges and cantilevers made of stress compensated films are given.
Interface and Bulk Traps in Oxide-Nitride Stacked Films
Authors: Martin Ferran , Aymerich Xavier 
Published: March 2011

ABSTRACTA new technique for the characterization of nitride electron traps responsible for the memory action of MNOS devices is proposed. It is assumed a uniform density of traps in the nitride bulk and an excess of interface traps which is described according to an exponential decreasing distribution. We have modelled the discharge of MNOS devices induced by the application of low positive gate voltages in samples previously charged up toits maximum level of trap occupancy. Since the discharge rate is necessarily dependent on the trapped charge distribution, it is possible to infer the spatial profile of traps by comparing the results obtained by computer simulation of the model to those obtained from field assisted discharge experiences in MNOS samples.
Electrical Properties of Oxide-Nitride-Oxide, Ono, Heterostructures Fabricated by Low Temperature Remote PECVD
Authors: Ma Y. , Yasuda T. , Chen Y. L. , Lucovsky G. , Maher D. M. 
Published: March 2011

ABSTRACTOxide-Nitride-Oxide, ONO, heterostructures, fabricated by low-temperature, 300°C, Remote Plasma Enhanced Chemical Vapor Deposition, have been used as gate dielectrics in metal insulator semiconductor devices. Analysis of C-V data for this devices indicates that higher levels of fixed charge are associated with the internal dielectric interfaces. A high-temperature, ̃900°C, Rapid Thermal Annealing, RTA, step has been inserted into the process sequence for fabricating ultra-thin, 4.7 nm SiO2 equivalent, device-quality ONO dielectric layers. The electrical properties of these ONO dielectrics, including the Si/SiO2 interfacial trap density, the flat band voltage, the charge to breakdown and the reliability under electron injection are comparable to those of high temperature, thermally-grown oxides.
Comparative Study of Simultaneous Implant Activation and Borophosphosilicate Glass (BPSG) Reflow During Rapid Thermal Processing (RTP) and Furnace Annealing on Complex Topographies
Authors: Thakur Randhir P. S. , Ward Valerie , Martin Annette 
Published: March 2011

ABSTRACTBorophosphosilicate glass (BPSG) is an essential insulating material used to modify thecomplex topography of highly dense, next generation dynamic random access memory (DRAM)devices. The shallow junctions in 16 and 64 Meg DRAMs can only be maintained by severely restricting the time, temperature, and atmosphere of all thermal process steps following the junction implant.In this paper we present the results of rapid thermal process (RTP) assisted reflow of BPSG over complex topographies and compare the results of RTP to furnace reflow in both dry and wet ambients. We also compare the out-diffusion of boron and phosphorous from BPSG films during the RTP and furnace reflow. We found an optimum RTP cycle that completely removes voids in the vicinity of overhang geometries and provides sufficient activation of the underlying dopants (as compared to a furnace reflow and activation cycle). In this study we used the results of boron and phosphorous profile redistribution, underlying dopant activation, and the amount of reflow to compare RTP and furnace processing techniques.
Defect Reduction in Semiconductor Manufacturing a Case Study of BPO4 Elimination in BPSG Films
Authors: Wilson Jim , Stephens Tony 
Published: March 2011

ABSTRACTThis paper explains the analysis and elimination of BPO4 crystal formation in an Atmospheric Pressure Chemical Vapor Deposition BPSG film. Film deposition and furnace anneal/flow parameters were studied using full factorial techniques, with anneal/flow parameters having the most significant effect. It was learned that BPO4 crystals could be readily induced by performing the anneal/flow process in a POCl3/O2 ambient. Most testing was done in a POCl3/O2 ambient and inferences made concerning the standard anneal ambient.BPO4 formation is primarily dependent on thermal processing during anneal toprovide the activation energy necessary to initiate crystal growth. Other factors include 02:Hydride ratio during film deposition, phosphorous concentration in the deposited film, deposition temperature, and anneal/flow ambient. No tested level of these secondary factors completely eliminated crystal formation.The growth of BPO4 crystals can be eliminated by controlling the thermal environment ofthe anneal/flow step. The primary means employed was to increase the rate of heat dissipation by doubling the spacing between wafers. An alternative method involves utilization of reduced anneal/flow furnace temperatures.