bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Boron Doping on Microcrystalline Germanium Carbon Thin Films
Authors: YASHIKI Yasutoshi , KOUKETSU Seiichi , MIYAJIMA Shinsuke , YAMADA Akira , KONAGAI Makoto 
Published: April 2011

AbstractEffects of boron doping on microcrystalline germanium carbon alloy (μc-Ge1-xCx:H) thin films have been investigated. We deposited boron-doped p-type μc-Ge1-xCx:H thin films by hot-wire chemical vapor deposition technique using hydrogen diluted monomethylgermane (MMG) and diborane (B2H6). A dark conductivity of 1.3 S/cm and carrier concentration of 1.7 x 1020 cm-3 were achieved with B2H6/MMG ratio of 0.1. Furthermore, the activation energy decreased from 0.37 to 0.037 eV with increasing B2H6/MMG ratio from 0 to 0.1. We also fabricated p-type μc-Ge1-xCx:H/n-type c-Si heterojunction diodes. The diodes showed rectifying characteristics. The typical ideality factor and rectifying ratio were 1.4 and 3.7 x 103 at ¡Ó 0.5 V, respectively.
A Novel Bonding Technique Using Metal-Induced Crystallization of Amorphous Silicon
Authors: Ong Markus D. , Dauskardt Reinhold H. 
Published: April 2011

AbstractThis study investigates the used of aluminum-induced crystallization of amorphous silicon is a potential bonding mechanism for a sandwich stack of films between two silicon substrates. Similar procedures using copper diffusion bonds have been in use, but these require temperatures as high as 400°C. Using the crystallization of amorphous silicon as the bonding mechanism has allowed the bonding temperature to be lowered by more than 100 K. Fracture experiments for a low-k material were conducted, and the results using amorphous silicon bonding was compared to epoxy bonding control experiments. Essentially identical results were obtained for the two bonding mechanisms. Low-temperature bonding techniques are of great interest to future progress in the microelectronics industry, and these results are promising advances.
Deposition Uniformity Control in a Commercial Scale HTO-CVD Reactor
Authors: Sakai Shigeru , Ogino Masaaki , Shimizu Ryosuke , Shimogaki Yukihiro 
Published: April 2011

AbstractHigh-temperature silicon dioxide chemical vapor deposition (HTOCVD), using SiH2Cl2 and N2O, can realize dense and conformal oxide film, not only on large size silicon wafers, but even inside of microscopic silicon trenches, at high-temperature around 800°C.In this work, we investigated the kinetics of HTOCVD using a commercial scale low pressure (LP) CVD reactor, focusing on the correlation between deposition rate and surface-to-volume ratio (S/V ratio), which is a specific surface area of substrate wafer divided by the space volume between two adjacent wafers. We also investigated the deposition rate profile on wafers, and along the axial direction of the reactor near the region where one, two or three substrate wafers are extracted from the quartz holder. The deposition rate profiles on wafer characteristically change from skillet-like to pancake-like, according to the increase of wafer spacing. The influence on the deposition rate of wafer spacing spreads to ranges not only downstream, but also upstream in the gas flow. These experimental results strongly suggest that in the HTOCVD gas-phase reactions through intermediate states of active species contribute to deposition reaction as well as direct deposition reaction of source gases on Si surface.
Monolithic Integrated a-Si:H based pin-Diodes with Orthogonal Liquid Light Guidance Structures for Lab-on-Microchip Applications
Authors: Schäfer Heiko , Seibel Konstantin , Schöler Lars , Böhm Markus 
Published: April 2011

AbstractWe report the fabrication of an amorphous silicon based fluorescence sensor for miniaturized total analysis systems along with experimental results on optical excitation and detection elements. The pin-photodiode exhibits a dynamic range of 110dB and a room temperature dark current of less than 3000 charge carriers per ms according to a detector area of 0.1256mm2. The spectral response is ranging from 320nm to 780nm with a maximum at 600nm @ 80% quantum efficiency. To provide high sensitivity, the excitation light irradiates the fluid orthogonally to the active sensor detection direction by means of specifically designed microfluidic capillaries filled with e.g. methylene iodide or 1,2-o-dibrombenzene. The liquid core, which is enclosed by solid cladding materials, has been calculated to dimensions of a width of 16.75µm or 59.67µm with a height from 15µm to 50µm according to a number of propagating modes inside of 16 or 57, respectively.
Self-Aligned Nanocrystalline Silicon Thin-Film Transistor With Deposited n+ Source/Drain Layer
Authors: Cheng I-Chun , Wagner Sigurd 
Published: April 2011

AbstractWe demonstrated self-aligned nanocrystalline silicon (nc-Si:H) n-channel thin film transistors (TFTs) with directly deposited n+ layer. The silicon layers were deposited by plasma-enhanced chemical vapor deposition at a substrate temperature of 150°C. The TFTs were made in a staggered top-gate, bottom-source/drain geometry with a seed layer underneath. The self-alignment of top-gate to the bottom-source/drain was achieved by backside exposure photolithography through the glass substrate and the silicon layers, followed by a lift-off process. An extent of gate to source/drain overlap of 1.5 mm was obtained. The self-aligned TFTs have similar characteristics to their non-self-aligned counterpart. This result represents an important step toward directly deposited nc-Si:H TFT backplanes on plastic substrates.
Segmented Amorphous Silicon n-i-p Photodiodes on Stainless-Steel Foils for Flexible Imaging Arrays
Authors: Vygranenko Yuriy , Kerr R. , Kim K. H. , Chang J. H. , Striakhilev D. , Nathan A. , Heiler G. , Tredwell T. 
Published: April 2011

AbstractThis paper reports the first successful attempt to fabricate amorphous silicon (a-Si:H) n-i-p photodiodes on a thin stainless-steel foil substrate for medical X-ray imaging applications. Two architectures of the n-i-p-photosensor, where the top electrode is based on amorphous or polycrystalline ITO, have been developed and characterized. The impact of critical fabrication steps including the deposition of semiconductor layers, dry etch of the NIP stack, diode passivation and encapsulation, as well as a contact formation on the device performance is presented and discussed. The test structures comprising segmented photodiodes with an active area ranged from 0.126 × 0.126 to 1 × 1 mm2 have been fabricated on stainless-steel foils and on glass substrates for the purposes of process characterization. The fabricated samples are evaluated in terms of current-voltage, capacitance-voltage, and spectral response characteristics.
Germanium-Silicon Separate Absorption and Multiplication Avalanche Photodetectors Fabricated with Low Temperature High Density Plasma Chemical Vapor Deposited Germanium
Authors: Carroll Malcolm , Childs Kent , Serkland Darwin , Jarecki Robert , Bauer Todd , Saiz Kevin 
Published: April 2011

AbstractA desire to monolithically integrate near infrared (NIR) detectors with silicon complementary metal oxide semiconductor (CMOS) technology has motivated many investigations of single crystal germanium on silicon (Ge/Si) diodes [1-3]. Reduction of the epitaxy thermal budget below the typical chemical vapor deposition (CVD) in-situ clean temperature (Tin-situ clean > 780°C) is also increasingly desired to reduce integration complexity. Reduced temperature growth approaches have included p+-Ge/n-Si detectors formed with low temperature poly-Ge (e-beam evaporation) or heavily dislocated single crystal germanium (molecular beam epitaxy, T ~ 450°C), which have had dark currents of ~5 mA/cm2 and responsivities of ~15 mA/W at 1310 nm, despite the large number of defects in and at the Ge/Si interface. Responsivities in these materials are however low and believed to be limited by a small diffusion length (i.e., 5-30 nm [2, 4]) due to fast electron recombination in the defect rich germanium. In this paper, we evaluate a commercially available high density plasma chemical vapor deposition (HDP-CVD) process to grow low temperature (i.e., Tin-situ & Tepitaxy < ~450°C) germanium epitaxy for a p+-Ge/p-Si/n+-Si NIR separate absorption and multiplication avalanche photodetectors (SAM-APD). This device structure is of interest both to examine ways to enhance the responsivity with internal gain as well as to examine alternatives to InGaAs-InP structures for NIR Geiger mode (GM) detection. A silicon avalanche region is highly desirable for GM to reduce after-pulsing effects, which are related to defect density that are smaller in Si than in InP [5]. Despite the high defect densities in the Ge and at the interface, the Ge-Si APDs in this work are found to have relatively low dark count rates in Geiger mode.
Drain Bias Dependent Threshold Voltage Shift of a-Si:H TFT Due to the Pulsed Stress
Authors: Park Sang-Geun , Lee Jae-Hoon , Han Sang-Myen , Kim Sun-Jae , Han Min-Koo 
Published: April 2011

AbstractWe have investigated the shift of threshold voltage in the a-Si:H TFT due to the various negative pulse width stress. The drain bias dependent threshold voltage shift in the pulsed stress of a-Si:H TFT for AMOLED backplane is also measured and analyzed. When a positive gate and drain bias is applied to a-Si:H TFT (W/L = 200/4 Ým), VTH of a-Si:H TFT is increased during the stress time due to the defect state creation and charge trapping. VTH of a-Si:H TFT is increased from 1.645V to 2.53V (δVTH=0.885V) after the DC gate bias stress of VGS=15V, VDS=0V for 20,000sec. When the pulsed negative bias stress is applied to the gate electrode of the current driving a-Si:H TFT with the drain bias, VTH shift is considerably reduced due to the hole trapping into the gate insulator during the stress. When a negative pulse width is 16msec (pulse of 60Hz), the VTH is increased form 1.594V to 2.195V (δVTH=0.601V). When a negative pulse width increases from 16msec to 5sec without drain bias (VDS=0V), VTH is increased from 1.615V to 2.055V (δVTH=0.44V). When a drain bias is increased from 0V to 15V, VTH is slightly decreased from 1.58V to 1.529V (δVTH=-0.051V) due to large (-30V) VGD (VG=-15V, VD=15V) bias, while it is increased from 1.66V to 2.078V (δVTH=0.418V) width DC gate bias stress of VGS=15V, VDS=15V for 20,000sec.
Noise Performance of High Fill Factor Pixel Architectures for Robust Large-Area Image Sensors using Amorphous Silicon Technology
Authors: Lai Jackson , Vygranenko Yuri , Heiler Gregory , Safavian Nader , Striakhilev Denis , Nathan Arokia , Tredwell Timothy 
Published: April 2011

AbstractLarge area digital imaging made possible by amorphous silicon thin-film transistor (a-Si TFT) technology, coupled with a-Si photo-sensors, provides an excellent readout platform to form an integrated medical image capture system. Major development challenges evolve aroundoptimization of pixel architecture for detector fill factor, signal propagation performance, and manufacturability, while suppressing noise stemming from pixel array and external electronics. This work analyzes a novel vertically integrated pixel design based on signal readout and noise performance, and compares with conventional co-planar and continuous detector architectures. In addition, the analysis will consider various substrate options including glass and robust substrates such as polymer and metal foil. Our evaluation have demonstrated state-of-the-art radiographic detector system with electronic noise under 2000 electrons at 150 µs frame time for an imaging arrays on robust substrate.
Triple Junction n-i-p Solar Cells with Hot-Wire Deposited Protocrystalline and Microcrystalline Silicon
Authors: Schropp Ruud E.I. , Li Hongbo , Franken Ronald H.J. , Rath Jatindra K. , van der Werf Karine , Schüttauf Jan Willem , Stolk Robert L. 
Published: April 2011

AbstractWe have implemented a number of methods to improve the performance of proto-Si/proto-SiGe/&#956;c-Si:H triple junction n-i-p solar cells in which the top and bottom cell i-layers are deposited by Hot-Wire CVD. Firstly, a significant current enhancement is obtained by using textured Ag/ZnO back contacts developed in house instead of plain stainless steel. We studied the correlation between the integrated current density in the long wavelength range (650-1000 nm) with the back reflector surface roughness and clarified that the rms roughness from 2D AFM images correlates well with the long wavelength response of the cell when weighted with a Power Spectral Density function. For single junction 2-μm thick μc-Si:H n-i-p cells we improved the short circuit current density from the value of 15.2 mA/cm2 for plain stainless steel to 23.4 mA/cm2 for stainless steel coated with a textured Ag/ZnO back reflector.Secondly, we optimized the μc-Si:H n-type doped layer on this rough back reflector, the n/i interface, and in addition used a profiling scheme for the H2/SiH4 ratio during i-layer deposition. The H2 dilution during growth was stepwise increased in order to prevent a transition to amorphous growth. The efficiency that was reached for a single junction μc-Si:H n-i-p cell was 8.5%, which is the highest reported value for hot-wire deposited cells of this kind, whereas the deposition rate of 2.1 Å/s is about twice as high as in record cells of this type so far. Moreover, these cells show to be totally stable under light-soaking tests.Combining the above techniques, a rather thin triple junction cell (total silicon thickness 2.5 &#956;m) has been obtained with an efficiency of 10.9%. Preliminary light-soaking tests show that this type of triple cells degrades by less than 4%.
Fabrication and Optimization of a-Si:H n-i-p Single-junction Solar Cells with 8 Å/s Intrinsic Layers of Protocrystalline Si:H Materials
Authors: Cao Xinmin , Du Wenhui , Ishikawa Y. , Liao Xianbo , Collins Robert W. , Deng Xunming 
Published: April 2011

AbstractAt the University of Toledo (UT), we have investigated hydrogenated amorphous silicon (a-Si:H) n-i-p solar cells with intrinsic layers deposited at high rates, ~ 8 Å/s, using our UT multi-chamber load-locked PECVD system. a-Si:H i-layers were grown with a VHF plasma density of ~ 0.2 W/cm2 and a frequency of 70 MHz using various hydrogen dilution levels. It is observed from the current-voltage (I-V) device performance characteristics that the open-circuit voltage (Voc) increases with increasing hydrogen dilution reaching a maximum and then decreasing. This drop in Voc can be attributed to the transition region (or protocrystalline regime) from an amorphous phase into a mixed amorphous+nanocrystalline (a + nc) phase for the i-layer. An initial efficiency of 9.99% (Voc = 0.986 V, Jsc = 13.98 mA/cm2, FF = 72.5%) was obtained. Quantum efficiency (QE) measurement has shown that the blue light response increases as the hydrogen dilution increases. Very good blue light spectral response with QE values over 0.7 at the wavelength of 400 nm have been obtained for a-Si:H cells made under specific deposition conditions in which tailored protocrystalline silicon materials were incorporated at the i/p interface region.
High-Performance, Tandem-Type Amorphous Silicon Solar Cell
Authors: Sichanugrist Porponth , Pingate Nirut , Piromjit Channarong 
Published: April 2011

AbstractMicrocrystalline silicon oxide (μc-SiO) deposited from the gas mixture of silane and carbondioxide using VHF plasma was reported by authors to be the promising material for thin-film silicon solar cell fabricated on glass substrate, comparing with the conventional amorphous silicon oxide or microcrystalline silicon p-layer. High-performance, tandem-type solar cell with amorphous and microcrystalline cells (double cells) has been achieved by ap-plying this μc-SiO to the p-layer of both cells.Further work has been extended to a-Si tandem type solar cell with triple cell configu-ration using amorphous silicon oxide (a-SiO), amorphous silicon germanium (a-SiGe) and microcrystalline Si (μc-Si) as the top, middle and bottom cells, respectively. Up to now, cell efficiency of 15.7 % has been achieved using this novel μc-SiO.
Study of a Fabrication Process and Characterization of One Dimensional Array of Un-cooled Micro-bolometers Based on Germanium Films Deposited by Plasma
Authors: Moreno Mario , Kosarev Andrey , Torres Alfonso , Ambrosio Roberto 
Published: April 2011

AbstractIn our previous works we have studied the fabrication process and characterization of single cell micro-bolometers based on germanium thin films deposited by low frequency (LF) PECVD technique at low temperature and fully compatible with the IC fabrication technology. We have demonstrated promising properties of those devices for further development of IR imaging systems.In this work we report the study of a fabrication process and characterization of one dimensional array of 32 un-cooled micro-bolometers. We have used surface micro-machining techniques for the array fabrication onto a silicon wafer. The micro-bolometers in the array have a “bridge type” configuration, in which a SiNx supporting film is suspended 2.5 μm from the substrate by two legs forming the bridge in order to provide sufficient thermo-isolation for thermo-sensing layer, which is deposited by LF PECVD over it. The a-GexSiy:H film used in this devices showed high activation energy Ea= 0.34 eV, providing high thermal coefficient of resistance, TCR=α=0.043 K-1 and improved but still high resistance. We studied the effect of include boron in the a-GexSiy:H film deposition process in order to reduce its undesirable high resistance and we used this layer (a-GexBySiz:H) as thermo-sensing film in the micro-bolometers arrays also. The active area of the cells in the array is Ab=70×66 μm2 and the area of the array including interconnection lines and pads is A=1600×3120 μm2. The temperature dependence of conductivity &#963;(T), current-voltage characteristics I(U) and spectral noise density have been measured in the micro-bolometers in the array in order to characterize and compare their performance characteristics, such as responsivity and detectivity.
High Performance Hydrogenated Amorphous Silicon n-i-p Photo-diodes on Glass and Plastic Substrates by Low-temperature Fabrication Process
Authors: Kim Kyung Ho , Vygranenko Yuriy , Bedzyk Mark , Chang Jeff Hsin , Chuang Tsu Chiang , Striakhilev Denis , Nathan Arokia , Heiler Gregory , Tredwell Timothy 
Published: April 2011

AbstractWe report on the fabrication and characterization of hydrogenated amorphous silicon (a-Si:H) films and n-i-p photodiodes on glass and PEN plastic substrates using low-temperature (150°C) plasma-enhanced chemical vapor deposition. Process conditions were optimized for the i-a-Si:H material which had a band gap of ~1.73 eV and low density of states (of the order 1015 cm-3). Diodes with 0.5 μm i-layer demonstrate quantum efficiency ~70%. The reverse dark current of the diodes on glass and PEN plastic substrate is ~10-11 and below 10-10 A/cm2, respectively. We discuss the difference in electrical characteristics of n-i-p diodes on glass and PEN in terms of bulk- and interface-state generation currents.
Evolution of Structural and Electronic Properties in Boron-doped Nanocrystalline Silicon Thin Films
Authors: Lee Hyun Jung , Sazonov Andrei , Nathan Arokia 
Published: April 2011

AbstractWe report on the boron-doping dependence of the structural and electronic properties in nanocrystalline silicon (nc-Si:H) films directly deposited by plasma- enhanced chemical vapor deposition (PECVD). The crystallinity, micro-structure, and dark conductivity of the films were investigated by gradually varying the ratio of trimethylboron [B(CH3)3 or TMB] to silane (SiH4) from 0.1 to 2 %. It was found that the low level of boron doping (< 0.2 %) first compensated the nc-Si:H material which demonstrates slightly n-type properties. As the doping increased up to 0.5 %, the maximum dark conductivity (ód) of 1.11 S/cm was obtained while high crystalline fraction (Xc) of the films (over 70 %) was maintained. However, further increase in a TMB-to-SiH4 ratio reduced ód to the order of 10-7 S/cm due to a phase transition of the films from nanocrystalline to amorphous, which was indicated by Raman spectra measurements.P-channel nc-Si:H thin film transistors (TFTs) with top gate and staggered source/drain contacts were fabricated using the developed p+ nc-Si:H layer. The fabricated TFT exhibits a threshold voltage (VTp) of -26.2 V and field effective mobility of holes (μp) of 0.24 cm2/V·s.
Wafer Level Modeling of Electrochemical-Mechanical Polishing (ECMP)
Authors: Truque Daniel , Xie Xiaolin , Boning Duane 
Published: April 2011

ABSTRACTIn this work, we propose a wafer level dynamic ECMP model based on time-evolving current density distributions across the wafer. The copper layer on the wafer surface is discretized, and the potential and current density distributions are calculated based on the applied voltage zones and metal film thicknesses across the wafer. The copper removal rate is proportional to the current density, and thus the copper thickness (and conductance) can be calculated as a function of position on the wafer and polish time. Using a time-stepping simulation, the model is able to capture the wafer level non-uniformity and time-dependence of ECMP removal. The model is also able to capture the time-varying voltage zones used in ECMP, and can be used to find optimal voltage zone control schemes to achieve improved wafer-level uniformity.
Supercritical Fluid Deposition of Ruthenium Thin Films: A Kinetic Study
Authors: Karanikas Christos F. , Watkins James J. 
Published: April 2011

AbstractThe kinetics of the deposition of ruthenium thin films from the hydrogen assisted reduction of bis(2,2,6,6-tetramethyl-3,5-heptanedionato)(1,5-cyclooctadiene)ruthenium(II), [Ru(tmhd)2cod], in supercritical carbon dioxide was studied in order to develop a rate expression for the growth rate as well as to determine a mechanism for the process. The deposition temperature was varied from 240°C to 280°C and the apparent activation energy was 45.3 kJ/mol. Deposition rates up to 30 nm/min were attained. The deposition rate dependence on precursor concentrations between 0 and 0.2 wt. % was studied at 260°C with excess hydrogen and revealed first order deposition kinetics with respect to precursor at concentrations lower then 0.06 wt. % and zero order dependence at concentrations above 0.06 wt. %. The effect of reaction pressure on the growth rate was studied at a constant reaction temperature of 260°C and pressures between 159 bar to 200 bar and found to have no measurable effect on the growth rate.
Novel [Topography-Sensitive] Bottom-Up Growth of Ruthenium and Copper for Filling Nano-Features Using Supercritical Co2 Fluids: Beyond Scalability
Authors: Kondoh Eiichi , Hirose M. , Ukai E. , Nagano K. 
Published: April 2011

AbstractA novel selective and bottom-up deposition process from supercritical CO2 is proposed and demonstrated. Supercritical CO2 fluids are dense media, and a deposition precursor dissolving wherein can easily condences in hollow/concave features. By combining this capillary condensation phenomenon with proper reaction chemistry, it was realized to deposit Ru an Cu in holes and trenches structures preferentially. The capillary condensation occurs better in the narrower features, we call this method “gtopography-sensitive” selective deposition technique.
Novel vapor phase method for making ultra thin conformal films of polytetrafluoroethylene (PTFE)
Authors: Gupta Sushant , Chakkaravarthi Arul Arjunan , Singh Rajiv , Opalko Jeff , Singh Deepika 
Published: April 2011

AbstractUltra-thin conformal polytetrafluoroethylene (PTFE) films were prepared by a novel physical vapor technique i.e., pulsed electron deposition (PED) technique. Prepared PTFE or Teflon thin films show high degree of conformity on patterned substrates. Under optimized deposition conditions the films exhibit superhydrophobicity. The PED processed films were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM) micrographs and the surface morphology and the conformal nature of the films were studied. The chemical nature and hydrophobicity were studied by FTIR and contact angle measurements, respectively.