bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in the Medium Range Order of α-Si:H Thin Films Observed by Variable Coherence Tem
Authors: Gibson J. M. , Treacy M. M. J. , Voyles P. M. , Abelson J. R. , Jin H.-C. 
Published: April 2011

ABSTRACTWe have investigated the structure of a-Si:H thin films using variable coherence transmission electron microscopy. Variable coherence is a new microscopy technique that is sensitive to higher-order atomic position correlations. We observe changes in the structure of α-Si:H with increasing hydrogen content and with light soaking. Based on these observations we conclude that a less ordered form of α-Si:H is more structurally stable than a more ordered form. This may have implications for understanding the Staebler-Wronski effect.
Real Time Spectroscopic Ellipsometry Studies of the Solid Phase Crystallization of Amorphous Silicon
Authors: Fujiwara H. , Koh Joohyun , Lee Yeeheng , Wronski C. R. , Collins R. W. 
Published: April 2011

ABSTRACTWe have introduced real time spectroscopic ellipsometry (RTSE) for characterization of the solid phase crystallization (SPC) of intrinsic and n-type amorphous silicon (a-Si:H) thin films. RTSE has several advantages in the study and design of SPC processes for thin film transistor and solar cell fabrication. These include the capability of obtaining (i) calibration data that yield the near surface temperature of the film during processing, (ii) the volume fraction of the crystalline Si component of the film continuously versus time during SPC, and (iii) a measurement of the grain size and quality of the final polycrystalline Si film. For the thin layers studied here (∼150-1000 Å), we demonstrate excellent fitting of the SPC dynamics to the Avrami-Johnson-Mehl theory for random nucleation and two-dimensional crystallite growth. For a-Si:H n-layers, the crystallization time over the range from 565 to 645°C appears to be weakly activated with an energy of 0.6 eV.
Thermochemistry of Silicon Lpcvd Revisited with Kinetic Data
Authors: Vahlas Constantin , Blanquet Elisabeth 
Published: April 2011

ABSTRACTPartial equilibrium calculations simulating the kinetically controlled low pressure chemical vapor deposition of silicon from silane are presented. Firstly, the sticking coefficient of each reactive species (σ) is evaluated by means of homogeneous calculations in the gas phase. Then, in a series of heterogeneous calculations, the influence of σ on the formation of the film is considered a) by reducing the quantities of the reactive species in the input gas, and b) by modifying their thermodynamic data. The obtained composition of the gas phase is used to estimate its supersaturation and the driving force for the deposition of silicon. The results are correlated with the morphology of the films deposited in equivalent conditions and, in view of this correlation, the validity of the presented approach is discussed.
µc-Si:H Thin-Film Devices for Optical Image Recognition
Authors: Maçarico A. , Fernandes M. , Martins J. , Vieira M. 
Published: April 2011

AbstractA study of an image detector based on µc-Si:H p-i-n structures is presented. The photodetector has a TCO/µc-p-i-n Si:H configuration with two coplanar metallic contacts and a transverse one.We used a strong spatially fixed light pattern with different intensities to simulate the images and a weak moving light beam to sweep the device in the lateral direction, for its recognition. The sensor surface was scanned row by row and a signal processing procedure was applied to the data after each sweep. It was found that the induced transverse and lateral photovoltages are sensitive to the position and intensity of the image. Through a readout analysis it was possible to recognise, in a continuous way, the image position and relative intensity. The image resolution as a function of the pattern width and intensity is also analysedA small signal circuit modelling and a simulation consistent with the experimental data are presented and explained. Preliminary tests show that the detector can be used as a two-dimensional image sensor.
Reaction Processes for Low Temperature (<150°C) Plasma Enhanced Deposition of Hydrogenated Amorphous Silicon Thin-Film Transistors on Transparent Plastic Substrates
Authors: Parsons Gregory N. , Yang Chien-Sheng , Klein Tonya M. , Smith Laura 
Published: April 2011

AbstractThis article presents mechanisms for low temperature (<150°C) rf plasma enhanced chemical vapor deposition of silicon and silicon nitride thin films that lead to sufficient electronic quality for thin film transistor (TFT) fabrication and operation. For silicon deposition, hydrogen abstraction and etching, and silicon disproportionation reactions are identified that can lead to optimized hydrogen concentration and bonding environments at <150°C. Nitrogen dilution of SiH4/NH3 mixtures during silicon nitride deposition at low temperatures helps promote N-H bonding, leading to reduced charge trapping. Good quality amorphous silicon TFT's fabricated with a maximum processing temperature of 110 °C are demonstrated on flexible transparent plastic substrates. Transistors formed with the same process on glass and plastic show linear mobilities of 0.33 and 0.12 cm2/Vs, respectively, with ION/IOFF ratios > 106.
Relationship of Field Emission Characteristics on Process Gas Nitrogen Content in Nitrogen Doped Diamond Films
Authors: Sowers A.T. , Ward B.L. , Nemanich R.J. 
Published: April 2011

AbstractThis study explores the field emission properties of nitrogen doped diamond grown by microwave plasma CVD. Several diamond samples were grown on silicon under varying conditions. With certain process parameters, films can be grown which exhibit photoluminescence bands at 1.945eV and 2.154eV that are attributed to single substitutional nitrogen. Field emission characteristics were measured in ultrahigh vacuum with a position variable anode. For samples grown with gas phase [N]/[C] ratios less than 16, damage from micro-arcs occurred during the field emission measurements. Samples grown at higher [N]/[C] content could be measured without damage. These measurements indicate relatively high threshold fields (>100V/µm) for electron emission. From the data, two possible field emission mechanisms are presented. Conducting defect states in the bandgap of diamond may provide a source of electrons to the emitting diamond surface.
Systematic Study of Transparent Conductors in the (Zinc, Gallium)-Indium-Tin Oxide Systems
Authors: Palmer George B. , Poeppelmeier Kenneth R. , Edwards Doreen D. , Mason Thomas O. 
Published: April 2011

AbstractBulk samples of transparent conducting oxides (TCOs) in the Zn-In-Sn and Ga-In-Sn oxide systems were prepared by solid state processing. Phase relations and physical properties were determined and the results compared to similar measurements on thin film materials.
Transistors With a Profiled Active Layer Made by Hot-Wire CVD
Authors: Meiling H. , Brockhoff A.M. , Rath J.K. , Schropp R.E.I. 
Published: April 2011

AbstractIn order to obtain stable thin-film silicon devices we are conducting research on the implementation of hot-wire CVD amorphous and polycrystalline silicon in thin-film transistors, TFTs. We present results on TFTs with a profiled active layer (deposited at ≥9 Å/s), and correlate the electrical properties with the structure of the silicon matrix at the insulator/semiconductor interface, as determined with cross-sectional transmission electron microscopy. Devices prepared with an appropriate H2 dilution of SiH4 show cone-shaped crystalline inclusions. These crystals start at the interface in some cases, and in others exhibit an 80nm incubation layer prior to nucleation. The crystals in the TFrs with the incubation layer are not cone-shaped, but are rounded off. The hot-wire CVD deposited devices exhibit a high field-effect mobility up to 1.5 cm2V−1s−1. Also, these devices have superior stability upon continuous gate bias stress, as compared to conventional glow-discharge a-Si:H TFTs. We ascribe this to a combination of enhanced structural order of the silicon and a low hydrogen content.
Characterization of Transparent Conductors in Indium Zinc Oxide and Their Application to Thin-Film Transistor Liquid-Crystal Displays
Authors: Takatsuji H. , Hiromori T. , Tsujimoto K. , Tsuji S. , Kurodac K. , Sakac H. 
Published: April 2011

AbstractInvestigation of the properties of indium zinc oxide (IZO) thin films sputter-deposited on LCD-grade glass substrate showed that the resistivity of an IZO film decreases markedly as the substrate temperature is increased from room-temperature to 120°C. This phenomenon can be attributed to the growth of In-Zn intermetallic compounds in the amorphous region as a result of annealing. The compound growth was observed by plan-view transmission electron microscopy.Although the transmittance and resistivity of IZO are inferior to those of indium-tin oxide, these disadvantages do not present any difficulties in the practical use of IZO for designing TFT-LCDs. Since IZO is an amorphous material, we propose a five-mask process with this characteristic.
Co-Optimization of Si Thin-Film Deposition and Excimer Laser Anneal Processes for Fabrication of High-Performance p-Si TFTs
Authors: Voutsas A.T. , Marmorstein A. , Solanki R. 
Published: April 2011

AbstractIn this work we have co-optimized the deposition and excimer laser crystallization processes for formation of high quality, low-temperature, p-Si films (LPS). We have found that the post-ELA polysilicon structure is very sensitive to deposition process adjustments, collectively expressed by the deposition rate. At low rates the PECVD Si-film is deposited in the microcrystalline phase (µc-Si). Comparing µc-Si and a-Si film precursors, we have shown that at equivalent annealing conditions (laser energy density) polysilicon films obtained from µc-Si precursor demonstrate improved crystallinity (grain size, defect density). Polysilicon thin film transistors (p-Si TFTs) have been fabricated and characterized using this material and compared to our standard process. We have found that the performance of µc-Si precursor exceeds by 20-50% that of a-Si precursor. Use of µc-Si precursor may also have important implications in reducing substrate damage during ELA process and for widening the ELA process window.
a-Si:H TFTs Made on Polyimide Foil by PE-CVD at 150°C
Authors: Gleskova H. , Wagner S. , Suo Z. 
Published: April 2011

AbstractWe have fabricated high-performance amorphous silicon thin-film transistors (a-Si:H TFTs) on 2 mil. (51 µm) thick polyimide foil substrates. The TFT structure was deposited by r.f.-excited plasma enhanced chemical vapor deposition (PECVD). All TFT layers, including the gate silicon nitride, the undoped, and the n+ amorphous silicon were deposited at a substrate temperature of 150°C. The transistors have inverted-staggered back-channel etch structure. The TFT off-current is ∼ 10−12 A, the on-off current ratio is > 107, the threshold voltage is 3.5 V, the sub-threshold slope is ∼ 0.5V/decade, and the linear-regime mobility is ∼ 0.5 cm2V−1s−1. We compare the mechanical behavior of a thin film on a stiff and on a compliant substrate. The thin film stress can be reduced to one half by changing from a stiff to a compliant substrate. A new equation is developed for the radius of curvature of thin films on compliant substrates.
Structural Investigations of Laser-Crystallized Hydrogenated Amorphous Silicon
Authors: Toet D. , Smith P.M. , Sigmon T.W. , Qiu R. , Takehara T. , Sun S. , Tsai C.C. , Harshbarger W.R. 
Published: April 2011

AbstractWe investigated the structure of hydrogenated amorphous silicon, thin films crystallized by short pulses from a XeCl excimer laser at fluences for which total melting of the films occurs. Atomic force microscopy revealed that films prepared using optimized process conditions, leading to hydrogen contents ≤ 5 at.%, are smoother after laser crystallization than those prepared by laser-dehydrogenation. The roughness of the laser-crystallized films increases with their thickness, and can be reduced by multiple exposure. A better smoothing is obtained by partially remelting the films after the first irradiation. Transmission electron microscopy shows that the grains in the laser-crystallized films have sizes that are comparable to the film thickness.
Carbon Nanotube-Based Vacuum Microelectronic Gated Cathode
Authors: Xu Xueping , Brandes George R. 
Published: April 2011

AbstractA vacuum microelectronic device containing carbon nanotube electron field-emitters was developed and tested. The gated cathode was fabricated using conventional microelectronics fabrication techniques and a final, self-aligned, in situ carbon nanotube growth step. To our knowledge, this is the first vacuum microelectronics device with carbon nanotube field-emitters grown in situ with a catalytic growth process. The turn-on voltage of the cathode was less than 20 volts and the emission current density at 50 volts was as high as 9 mA-cm−2. The fabrication process, device performance, manufacturing issues and cathode applications will be discussed.
Quasi-Ballistic Stable Electron Emission from Porous Silicon Cold Cathodes
Authors: Sheng X. , Koshida N. 
Published: April 2011

AbstractBased on the previously-reported porosity multilayer technique, cold electron emission properties of porous silicon (PS) electroluminescent diodes with a structure of Au/PS/n-type Si are further improved by introducing a graded-band multilayer structure. It is shown that electrons are quasiballisticly emitted from PS diodes owing to a significantly reduced electron scattering in PS layer. As a result, the emission current shows a fluctuation-free behavior. These observations are very important for both understanding the electron transport in PS and developing high performance electron emitters in application to vacuum microelectronic technology.
A Novel Lateral Field Emission Triode for Microwave Application
Authors: Park C-M , Lim M-S , Han M-K , Choi Y-I 
Published: April 2011

AbstractWe propose a novel lateral field emission triode, which does not require any additional vacuum sealing process and exhibits superb field emitter triode performance. The purpose of this paper is to compare titanium polycide tip with polycrystalline silicon tip. A new experimental results of the device, such as variation of tip material, device stability experiment, measurement of the novel device in vacuum chamber in order to verify the proposed vacuum sealing process, and transconductance characteristics at each current level.The minimum turn-on anode to cathode voltage of titanium polycide tip is considerably decreased compared with polysilicon tip. The anode current measured in 10−8 Torr vacuum chamber is similar to the anode current measured in atmospheric pressure, which shows that the proposed vacuum sealing process is reliable. The stable current of 300μΑ is maintained during 60 h.
Emitting Carbon Thin Films and Their Characterizations
Authors: Tolt Z. Li , Fink R. L. , Yaniv Zvi 
Published: April 2011

AbstractCarbon thin film cathodes have been produced with an emission site density of 2 × 105/cm2 and with current density higher than 40 mA/cm2at 10 V/μm extraction field. Characterization of the film bonding structure by UV Raman spectroscopy and emission sites by Atomic Force Microscopy (AFM) are presented and discussed in detail. A hypothesis of the nature of emission sites in these films is proposed in accordance with the analyses.
Characterizaton of Pecvd Fluorinated Silicon Oxides and Stabilization of Interaction with Metals
Authors: Kim Sarah E. , Steinbruichel Christoph , Kumar Atul , Bakhru H. 
Published: April 2011

ABSTRACTFluorinated silicon oxide films were prepared in a plasma enhanced chemical vapor deposition reactor using TEOS, O2, and either C2F6 or NF3. Properties such as deposition rate, film refractive index, dielectric constant, density, and fluorine concentration were investigated as a function of experimental conditions. Based on nuclear reaction analysis (NRA) and Fourier Transform Infrared (FTIR) measurements, no single linear relationship was found between fluorine concentration or film density and dielectric constant. Special attention was paid to the interaction of fluorine with metals. NRA and X-ray photoelectron spectroscopy (XPS) depth profiles showed that fluorine diffuses rapidly through aluminum and piles up at the free surface. The effect of various plasma treatments was investigated to passivate the surface of fluorinated silicon oxide. CF4 - O2 plasma treatment of the fluorinated oxide before aluminum deposition produced significant improvement in inhibiting fluorine diffusion into aluminum without increasing the dielectric constant.
Porous Silica Xerogel Processing And Integration For Ulsi Applications
Authors: Jin Changming , List Scott , Zielinski Eden 
Published: April 2011

ABSTRACTWith a tunable ultra low dielectric constant, porous silica xerogel is an attractive dielectric material for ULSI interconnect applications and is potentially extendable to multiple future technology nodes. Porous silica xerogel films have been processed and integrated into device test structures as ultra low k intermetal dielectrics. A fully automated thin film deposition process is recently developed and gives high throughput and good repeatability. A surface modification technique is used to make the films hydrophobic. The film dielectric constant is measured to be less than 2, depending on porosity. Because of the small pore sizes, the films display high dielectric break down strength. With proper shrinkage control, porous silica xerogel shows excellent gapfill capabilities. Integration of the porous silica xerogel material into CMP planarized double level metal (DLM) test structures with both Al and W plugs in a gapfill scheme is successful. Porous silica xerogel structures provide 14% and 35% total capacitance reduction compared to structures with hydrogen silsesquioxane (HSQ) and high density plasma (HDP) oxide respectively. Reliability and current leakage data of porous silica xerogel are comparable to that of HSQ. Feasibility of integrating porous silica xerogel into Cu damascene structures is also demonstrated. Cu/xerogel damascene structures exhibit improvements in both resistance and capacitance compared with convention Al/Oxide gapfill structures.
High-Density Plasma Etching of Low Dielectric Constant Materials
Authors: Standaert T. E. F. M. , Matsuo P. J. , Allen S. D. , Oehrlein G. S. , Dalton T. J. , Lu T.-M. , Gutmann R. 
Published: April 2011

ABSTRACTThe patterning of several novel low dielectric constant (K) materials has been studied in a high-density plasma (HDP) tool. Recent results obtained on oxide-like materials, such as fluorinated oxide, hydrogen silsesquioxane (HSQ), and methyl silsesquioxane (MSQ), are reviewed. These materials can be successfully patterned using a fluorocarbon etching chemistry. The etching is in this case controlled by a thin fluorocarbon film at the surface. The patterning of polymer dielectrics can be performed in an oxygen etching chemistry. As an example, the patterning of Parylene-N in an oxygen chemistry is discussed. In this case, the ion and the oxygen radical flux need to be properly controlled to obtain a directional etching process. After the dielectric etch, either in a fluorocarbon or oxygen based chemistry, fluorocarbons and oxygen contamination remain at the exposed metal surfaces. We recently demonstrated how a plasma treatment following the dielectric etch reduces these contaminants. The results of this treatment on copper surfaces and the resulting modification to the dielectric are reviewed.
Influence of Moisture-Uptake on Mechanical Properties of Polymers Used in Microelectronics
Authors: Buchhold R. , Nakladal A. , Gerlach G. , Sahre K. , Eichhorn K.-J. , Herold M. , Gauglitz G. 
Published: April 2011

ABSTRACTPolymers are currently considered as a possible alternative to silicon dioxide in the fabrication of interlevel dielectrics. To penetrate mainstream semiconductor device fabrication polymers have to meet a number of requirements regarding their long-term stability. One aspect is the mechanical stability of integrated polymer films under changing climatic conditions. In the present work, the impact of ambient moisture on the mechanical properties of thin polymer films (PI, BCB, and PFCB) was investigated. The sorption of water molecules in these materials typically causes an anisotropic volume expansion, resulting in increased mechanical film stress if the film is physically constrained by adjacent inorganic structures. Especially polyimides show both considerable moisture uptake and large changes in the mechanical film stress, while BCB and PFCB are virtually insensitive to ambient moisture. In the paper, experimental data (water uptake, in-plane swelling, out-of-plane swelling) are presented and discussed in detail.
High Temperature Stable Titanium Carbide Ohmic and Schottky Contacts to SiC
Authors: Zetterling C.-M. , östling M. , Norin L. , Jansson U. 
Published: April 2011

ABSTRACTEpitaxial titanium carbide is investigated as a low resistivity, high temperature stable Ohmic and Schottky contact to 4H and 6H SiC. The titanium carbide films were deposited at 500°C using co-evaporation of titanium (e-beam) and C60(Knudsen cell) in a UHV system. Schottky diodes and TLM structures were fabricated on low and high doped SiC material respectively. The samples were annealed at 700 °C in a vacuum furnace, and electrical measurements were performed up to 300 °C.
Low Frequency Noise In n-Type Gallium Nitride
Authors: Dyakonova N. , Levinshtein M. , Contreras S. , Knap W. , Beaumont B. , Gibart P. 
Published: April 2011

ABSTRACTLow frequency noise has been investigated in hexagonal n-type GaN with equilibrium electron concentration n ∼ 1017 cm−3 at T=300 K. The frequency and temperature dependencies of the spectral density of the current noise, SI, have been studied in the frequency range f from 20 Hz to 20 kHz. Over the whole temperature range from T=80K to 400K the SI(f) dependence is very close to 1/f. The value of the Hooge constant, α, is very large: α ∼ 5 – 7 and is found to be temperature independent. The effects of illumination on the low frequency noise in GaN are studied for the first time. The noise is unaffected by illumination with photon energy Eph < Eg, while band-to band illumination (Eph∼Eg ) influences the low frequency noise, increasing the noise at higher temperatures, and decreasing it at lower temperatures.
Effect Of No On The Electrical Characteristics Of SiO2 Grown On P-Type 4H SiC
Authors: Li H. F. , Dimitrijev S. , Harrison H. B. , Sweatman D. , Tanner P. 
Published: April 2011

ABSTRACTIn this paper the effect of NO nitridation on the electrical characteristics of the oxides grown on p-type 4H SiC has been investigated. The results show that NO nitrided oxide has a lower interfacial trap density and a lower net oxide charge compared to N2 annealed oxides.