bluuebunny/crossref_metadata_2025_split huggingface dataset:
Real Time Monitoring of the Crystallization of Hydrogenated Amorphous Silicon
Authors: Stradins Paul , Young David , Branz Howard M. , Page Matthew , Wang Qi 
Published: June 2019

AbstractIn-situ real-time optical reflectance spectroscopy is applied to investigate structural changes as hydrogenated amorphous silicon (a-Si:H) loses H and crystallizes at elevated temperature. The interference fringe spectrum (cutoff energy and amplitude) mainly characterize changes in the bulk, while the the crystal Si (c-Si) direct-transition ultra-violet reflectance signatures reveal the presence of any crystalline phase at the surface. Effusion of atomic hydrogen is monitored by a decrease of the interference fringe cutoff energy and is thermally activated with about 1.7 eV. In a-Si:H on glass, optical reflectance spectra are consistent with 2.8 eV activated homogeneous nucleation and growth of a small grain (˜ 100 nm) polycrystalline phase. In contrast, a-Si:H on c-Si crystallizes by solid phase epitaxy with very different spectral kinetics. Our measurements reveal the temperature-time window for thermal crystallization of a-Si:H for photovoltaic device applications, and highlight the versatility of the in-situ spectral reflectance monitoring.
Electrolyte-Gate a-Si:H Thin Film Transistors
Authors: Gonçalves Dina I. , Prazeres Duarte M. , Chu Virginia , Conde João P. 
Published: June 2019

AbstractThis paper presents the fabrication and characterization of electrolyte-gate (EG) hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs). In these devices, the metal gate is replaced by a Pt electrode immersed in an electrolyte. The source-drain current of these devices is modulated by the voltage applied through the Pt electrode. Device characteristics are compared with structurally equivalent top-gate a-Si:H TFTs. The EG devices show higher mobility and smaller subthreshold slope than their counterparts with metal gate and work in a narrower voltage range. EG-TFTs show chemical sensitivity, illustrated by a voltage shift in the transfer curve as a consequence of pH variation. The sensitivity of the devices to pH is different depending on whether the top layer in contact with the electrolyte is SiO2 or SiNx.
Dependence of Microcrystalline Silicon Growth on Ion Flux at the Substrate Surface in a Saddle Field PECVD
Authors: Johnson Erik , Kherani Nazir P. , Zukotynski Stefan 
Published: June 2019

AbstractThe Saddle-Field Glow Discharge PECVD system emulates RF-like excitation using a semi-transparent anode and a DC power supply. It has been used to deposit high quality amorphous and microcrystalline hydrogenated silicon thin films in the past. The growth of microcrystalline material is particularly sensitive to the conditions under which it is produced. Significant levels of microcrystallinity are only produced under conditions of higher pressure and electrical isolation of the substrate surface from the grounded substrate holder. We present results of a study on the relationship between substrate electrical potential and microcrystalline growth, as quantified by Raman scattering spectroscopy, at growth pressures near the minimum required for microcrystalline growth.
Improved optical loss characteristics of PECVD silicon oxynitride films using low frequency plasma
Authors: Naskara S. , Bower C.A. , Wolter S.D. , Stonera B.R. , Glass J.T. 
Published: June 2019

AbstractWith the continued growth of photonics, silicon oxynitride (SiOxNy) is becoming a popular material for optoelectronic applications owing to its large tunable refractive index. However, with the increase in refractive index, these films tend to show poor optical transmission characteristics. In this research we have investigated the influence of growth conditions on the loss characteristics of PECVD SiOxNy films. The films are grown at 350 °C substrate temperature and 1 Torr pressure with silane (SiH4) and nitrous oxide (N2O) precursor gases. The precursor flow rate and power input to the system are varied as the two primary parameters. It is observed that films grown at 100 kHz plasma frequency proved to be more transmissive than films grown at 13.56 MHz plasma frequency. Elastic recoil detection analysis results showed the hydrogen content is less in the low frequency films than the high frequency films, which is believed to be the reason for the low loss behavior. The details of these analysis results are discussed below.
Gate Oxide Integrity for Polysilicon Thin-film Transistors: A Comparative Study for ELC, MILC, and SPC Crystallized Active Polysilicon Layer
Authors: Choi D. C. , Choi B. D. , Jung J. Y. , Park H. H. , Seo J. W. , Lee K. Y. , Chung H. K. 
Published: June 2019

AbstractIn this paper, we present the results of Plasma Enhanced Chemical Vapor Deposition gate oxide (SiO2) integrity on ELC (excimer laser crystallized), MILC (metal induced lateral crystallized) and SPC (solid phase crystallized) polysilicon films. We observed that gate oxide strength of poly Si TFT strongly depends on the crystallization method for the active silicon layer. In the case of ELC films, asperities on the silicon surface reduce the SiO2 breakdown field significantly. The metallic contaminants in MILC films are responsible for a deleterious impact on gate oxide integrity. Among the three cases, the SiO2 breakdown field was the highest for the SPC silicon films. The breakdown fields at the 50% failure points in Weibull plots for the ELC, MILC and SPC cases were 5.1MV/cm, 6.2MV/cm, 8.1MV/cm, respectively. We conclude that the roughness and metallic contamination of the poly Si films are the main factors that cause en-hanced breakdown of SiO2 films.
The Hysteresis Analysis of Hydrogenated Amorphous Silicon Thin Film Transistors for an Active Matrix Organic Light Emitting Diode
Authors: Lee Jae-Hoon , You Bong-Hyun , Shin Kwang-Sub , Han Min-Koo 
Published: June 2019

AbstractAn experimental scheme for validating the cause of the hysteresis phenomenon in hydrogenated amorphous silicon thin film transistor (a-Si:H TFT) is reported. The different gate starting voltage to the desired gate voltage has been considered to prove an effect of filling an acceptor-like or donor-like state in the interface. The integration time of the semiconductor parameter analyzer (HP4156B) has also been controlled to investigate the effect between the detrapping rate and hysteresis. The experimental results show that the previous data voltage in the (n-1)th frame affects the OLED current in the (n)th frame.
Low Hydrogen Concentration Silicon Nitride as a Gate Dielectric of TFTs for Flexible Display Application
Authors: Park Joong Hyun , Kim Chang Yeon , Shin Kwang Sub , Park Sang Geun , Han Min Koo 
Published: June 2019

AbstractWe have proposed low hydrogen concentration (CH) silicon nitride (SiNX) as a dielectric for flexible display application. The fabrication temperature on plastic substrate is limited below Tg (glass transition temperature, typically 130˜180 °C) and it was reported that CH in thin film is strongly depends on fabrication temperature. As the fabrication temperature is decreasing, hydrogen concentration is increasing. SiNX deposited in ultra low temperature (< 150 °C) has high CH which is porous, low density. Our experimental results using SiH4, He, N2 gas mixture shows that in the SiNX CH is less than 15 at.%. Breakdown voltage of proposed SiNX dielectric is 5 MV/cm. In the wet etch rate test using a nitride etching solution, He dilution is more dense than NH3 dilution. This process approach is useful for flexible display application.
High Efficiency Solar Cells with Intrinsic Microcrystalline Silicon Absorbers Deposited at High Rates by VHF-PECVD
Authors: Mai Yaohua , Klein Stefan , Carius Reinhard , Geng Xinhua , Finger Friedhelm 
Published: June 2019

AbstractIntrinsic microcrystalline silicon (μc-Si:H ) was prepared at high deposition rates (RD) by very high frequency plasma-enhanced chemical vapor deposition (PECVD) working at high-pressure high-power (hphP). The material has similar electrical and optical properties as μc-Si:H material deposited at low rates by low-pressure low-power PECVD, apart from a more pronounced structure in-homogeneity along the growth axis for material deposited on glass substrates. With optimized deposition conditions high efficiency solar cells can be grown with deposition rates of up to 15 Å/s without deterioration of the performance as a function of RD. A high conversion efficiency of 9.8 % was obtained for a single junction μc-Si:H p-i-n solar cell at a deposition rate of RD = 11 Å/s.
Structural and Electronic Properties of Hydrogenated Nanocrystalline Silicon Films Made with Hydrogen Dilution Profiling Technique
Authors: Wang Keda , Han Daxing , Williamson D. L. , Huie Brittany , Weinberg-Wolf J. R. , Yan Baojie , Yang Jeffrey , Guha Subhendu 
Published: June 2019

AbstractWe used X-ray diffraction (XRD), Raman scattering and photoluminescence (PL) spectroscopy to characterize structural and electronic properties of nc-Si:H films made with different hydrogen dilution ratios and hydrogen dilution profiling with continuously reduced hydrogen dilution during the deposition. The XRD results show that the crystalline volume fraction (fc) is in the range of 60-70% with grain size of 22-26 nm for the nc-Si:H films studied. Comparing the sample made using hydrogen dilution profiling to that with constant hydrogen dilution, the hydrogen dilution profiling promotes the (220) preferential orientation due to a very high hydrogen dilution in the initial growth. The Raman results show that the fc is in the range of 60-90%, depending on the sample and excitation wavelength. For the samples with constant hydrogen dilution, the fc measured by Raman increases along the growth direction. The hydrogen dilution profiling reverses this trend, which affirms that the hydrogen profiling controls the nanocrystalline structure evolution along the growth direction. The PL results show only one peak around 0.8-0.9 eV for the samples made with constant hydrogen dilution, but an additional peak at 1.4 eV appears in the sample made with the hydrogen dilution profiling.
Conductance Fluctuations in Amorphous Silicon Nanoparticles
Authors: Belich T. J. , Shen Z. , Blackwell C. , Campbell S. A. , Kakalios J. 
Published: June 2019

AbstractHydrogenated amorphous silicon nanoparticles with an average diameter of 150 nm have been synthesized by high-density plasma chemical vapor deposition. The particles are deposited onto a conducting substrate and are then surrounded by an insulating matrix, electrically isolating the particles. Electrical contact is made to the top of each nanoparticle; the current-voltage characteristics of the nanoparticles indicate that transport is space-charge limited through the a-Si:H. The spectral density of the current fluctuations in the a-Si:H nanoparticles is well described by a 1/f frequency dependence for frequency f. However, the octave separation dependence of the correlation coefficients of the noise power for the nanoparticles are very well described by an ensemble of fluctuators whose amplitudes are independently modulated in parallel, rather than the serial kinetics typically observed in bulk a-Si:H.
Transport and Meyer-Neldel Rule in Microcrystalline Silicon Films
Authors: Reynolds Steve , Smirnov Vlad , Finger Friedhelm , Main Charlie , Carius Reinhard 
Published: June 2019

AbstractChanges in the electrical conductivity of thin (< 300 nm) silicon films following prolonged exposure to atmosphere, are reported. Both reversible (by annealing at 150 °C under vacuum) and irreversible (annealing-resistant) effects are found to occur, which are larger in thinner films. The conductivity prefactor and thermal activation energy obey the Meyer-Neldel rule, although detailed behaviour depends on film thickness and microstructure. Irreversible changes may result from oxidation of thinner, more porous films, with water and/or oxygen adsorption and desorption responsible for reversible changes. The need to identify and account for these effects when discussing and formulating transport mechanisms in these materials is underlined.
Formation of antimony 1D-nanostructures on Si (5 5 12) surface
Authors: Shivaprasad S. M. , Kumar Mahesh , Joshi Amish G. , Paliwal Vinod Kumar 
Published: June 2019

AbstractOf late, high index Si surfaces like, (5 5 12) are being explored for the formation of 1D nanostructures in the form of nanowires or chains. The surface topography of Si (5 5 12) presents an unique template for the growth of 1D nanostructures. In this paper we report the adsorption-desorption studies of Sb onto (2×1) reconstructed surface of Si (5 5 12). Motivated by our earlier studies of adsorption/desorption of Sb on low index surfaces (001) and (111), studying the interaction on high index surface like (5 5 12) is found to be interesting. The experiments have been performed in UHV with in-situ growth and probed by using AES, LEED and EELS techniques. The uptake curve shows initially a simultaneous multilayer growth of Sb up to 4 ML and then at 20 ML the entire Si surface is covered by Sb. The LEED patterns show a disorder during growth at RT above 1 ML. EELS studies at 250 eV, primary beam energy show that as the adsorption proceeds the features of bulk Sb start appearing above 4ML coverage. However, the bulk Sb features are not complete until a high enough coverage of Sb (˜20ML) which suggests the existence of the primary rows up to a higher coverage. Annealing studies have also been performed on the RT adsorbed system, to study the residual thermal desorption characteristics. Annealing the system to about 7900C results in Si (337) facets at a low coverage of 0.2 ML. The anisotropy in the LEED spots suggests an ordered Sb adsorption along (1 10) and a local disorder in the (665 ) direction. Thus we provide evidence for the formation of a zig-zag 1D-nanowire of Sb grown on the (5 5 12). The new phase is also accompanied by forming a dangling bond state at 3 eV in EELS.
Spectral Sensitivity and Color Selectivity in Multilayer Stacked Devices
Authors: Louro P. , Vieira M. , Fantoni A. , Fernandes M. , Lavareda G. , Carvalho C. Nunes de 
Published: June 2019

AbstractIn this work, an attempt of full color discrimination is presented using as sensitive devices multilayer stacked structures (p(SiC:H)/i(SiC:H)/n(SiC:H)/p(SiC:H)/i(Si:H)/n(Si:H)) sandwiched between two transparent conductive contacts. The thickness and the absorption coefficient of the front p-i-n cell is optimized for blue collection and red transmittance and the thickness of the back one adjusted to achieve full absorption in the green and high collection in the red spectral ranges. The current-voltage characteristics and the spectral sensitivity under different electric and optical bias conditions and light fluxes are analyzed. Results show that color selectivity is achieved by tuning the spectral sensitivity at different applied voltages. A physical model supports the results.
Effect of the hydrogen content in the optical properties and etching of silicon nitride films deposited by PECVD for uncooled microbolometers
Authors: Ambrosio R. , Torres A. , Kosarev A. , Landa M. , Heredia A. 
Published: June 2019

AbstractWe have studied silicon nitride films a-SiN:H deposited at a substrate temperature of 350°C by means of the Low frequency (LF) PECVD from silane and nitrogen as stock gases. Film properties as hydrogen bonding and content, nitrogen content, refractive index and etch rate are reported and analyzed. Our deposited films show physical properties similar to those that are obtained deposition temperatures of 700°C by the low pressure chemical vapor deposition (LPCVD) technique. An investigation of bonding structures for the deposited films was performed, and quantitative results for hydrogen bonding based on Fourier Transform Infrared (FTIR) analysis are presented. It was observed that low hydrogen content in the films is in good correlation with low etch rate in 10% buffered HF solution, therefore these films present a material with good etch selectivity in respect to others materials (as phosphosilicate glass PSG, Al etc). Selectivity which makes these films very promising in surface micromachining for fabrication of sensors and device structures, e.g. microbolometers. Additionally, the Si-N bond at 830-840cm-1was analyzed because of its big absorption produced at 12μm; therefore these films can be used as absorber layers in uncooled microbolometres.
Photoluminescence and electroluminescence properties of FeSi2-Si structures formed by MEVVA implantation
Authors: Chow C.F. , Gao Y. , Wong S.P. , Ke N. , Li Q. , Cheung W.Y. , Shao G. , Lourenco M.A. , Homewood K.P. 
Published: June 2019

AbstractWe have prepared FeSi2 precipitates of nanometer size in Si by ion implantation using a metal vapor vacuum arc (MEVVA) ion source and studied their photoluminescence properties. Broad photoluminescence (PL) spectra at around 1550 nm were observed for all samples attributed to emission from the FeSi2 precipitates. It was found that all the PL spectra can be decomposed into two peaks, a main peak at near 1530 nm and a satellite peak at 1607 nm. Samples with a furnace annealing (FA) step at a lower temperature of 850°C are found to have a main peak position at a longer wavelength close to 1540 nm. For samples with a FA step at higher temperatures, the main peak position shifts to shorter wavelengths of near 1525 nm. In addition, we have also prepared MOS structures with implanted FeSi2 precipitates incorporated in the structures and measured their EL properties. The EL properties from these FeSi2-Si MOS structures after various thermal treatments were measured as a function of temperature from 80 to 300 K. Our preliminary results show that clear EL signals are obtained even at room temperature under appropriate processing conditions.
Effect of Electromigration on Mechanical Behavior of Solder Joints
Authors: Ren Fei , Nah Jae-Woong , Gan Hua , Suh Jong-Ook , Tu King-Ning , Xiong Bingshou , Xu Luhua , Pang John 
Published: June 2019

AbstractElectromigration in solder joints causes a void formation between intermetallic compounds (IMC) and solder at the cathode. The effect of electromigration in mechanical test of Cu wires joined by solder was performed. The current density of electromigration was 1∼5×103 A/cm2. The working temperature was 100∼150°C. Tensile stress and shear stress were applied either before or after electromigration. The tensile strain rate was 3 μm/min. We observed that, without electromigration, tensile stress caused a ductile break at the middle of solders because the solder was softer. On the other hand, if combined with electromigration, a brittle failure always occurred at the cathodes interface during tensile test. The ultimate tensile strength decreased with longer electromigration time or higher current density. In shear test, the daisy chain of solders failed alternatively at the cathodes after electromigration.
Poly(ethynyl-p-xylylene), An Advanced Molecular Caulk CVD Polymer
Authors: Carrow Brad P. , Murray Rex E. , Woods Benjamin W. , Senkevich Jay J. 
Published: June 2019

AbstractPoly(p-xylylene) (also known as parylene N) has previously been used to pore seal ultralow k (≤ 2.2) (ULK) dielectrics. The parylene polymers may facilitate the integration of ULK dielectrics by: substantially improving their fracture toughness, hermetically sealing the pores, being able to use standard wet chemical cleans, and minimally impacting the observed dielectric constant, while minimally disrupting current process flow integrations. This paper introduces a new cross-linkable polymer that is deposited using thermal chemical vapor deposition (CVD) on the same tool that is used for parylene N deposition. The polymer, poly(ethynyl-p-xylylene) (parylene X), was deposited at room temperature. A series of 30 min post-deposition anneals in helium shows that the deposited material cross-linked between 200°C and 300°C with full conversion at 380°C for a ~300 A film. After the low molecular weight species out-gassed during anneals at 200°C, there was less than a percent weight loss to 450°C with no change in the optical constants and no optical loss. Previous work with poly(ethyl-p-xylylene) suggests that the dielectric constant of parylene X will be significantly lower than parylene N.
Barrier Integrity Effect on Leakage Mechanism and Dielectric Reliability of Copper/OSG Interconnects
Authors: Li Yunlong , Tökei Zsolt , Mandrekar Tushar , Mebarki Bencherki , Groeseneken Guido , Maex Karen 
Published: June 2019

AbstractIn this paper, we investigate the effect of copper diffusion barrier integrity on the leakage behavior and dielectric reliability of copper/micro porous organo-silica-glass (OSG) interconnects. Significant differences in the field dependence of TDDB median-time-to-failure are observed when comparing sub-critical and sealing barriers. Also for the temperature acceleration of TDDB, a significant difference is found which is reflected in the thermal activation energies. With fast voltage ramp measurements, I-V curves of samples with subcritical and sealing barriers are compared before and after constant current stresses. Above 1.4 MV/cm, the dominant leakage mechanism is found to be Frenkel-Poole emission regardless of barrier treatments and stress times. Below 1.4 MV/cm, however, the I-V characteristic is modulated by the barrier integrity, which can be attributed to copper diffusion into the intermetal dielectric.
TEM-Based Analysis of Defects Induced by AC Thermomechanical versus Microtensile Deformation in Aluminum Thin Films
Authors: Geiss R.H. , Keller R.R. , Read D.T. , Cheng Y.W. 
Published: June 2019

AbstractThin films of sputtered aluminum were deformed by two different experimental techniques. One experiment comprised passing high electrical AC current density through patterned Al interconnect lines deposited on SiO2/Si substrates. The other consisted of uniaxial mechanical tensile deformation of a 1 μm thick by 5 μm wide free standing Al line. In the electrical tests approximately 2 x 107 W/cm2 was dissipated at 200 Hz resulting in cyclic Joule heating, which developed a total thermomechanical strain of about 0.3 % per cycle. The tension test showed a gauge length fracture strain of only 0.5 % but did display ductile chisel point fracture. In both experiments, certain grains exhibited large, > 30°, rotation away from an initial <111> normal orientation toward <001>, based on electron backscatter diffraction (EBSD) measurements in the scanning electron microscope (SEM). Transmission electron microscopy (TEM) analysis of specimens from both experiments showed an unusually high density of prismatic dislocation loops. In the mechanically-tested samples, a high density of loops was seen in the chisel point fracture zone. In cross sections of highly deformed regions of the electrical test specimens, very high densities, > 1015/cm3, of small, > 10 nm diameter, prismatic loops were observed. In both cases the presence of a high density of prismatic loops shows that a very high density of vacancies was created in the deformation. On the other hand, in both cases the density of dislocations in the deformed areas was relatively low. These results suggest very high incidence of intersecting dislocations creating jogs and subsequently vacancies before exiting the sample.