bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Field-Aided Germanium-Induced Lateral Crystallization of Silicon
Authors: Naeli Kianoush , Mohajerzadeh Shamsoddin , Khakifirooz Ali , Haji Saber , Soleimani Ebrahim A. 
Published: April 2011

ABSTRACTThe effect of an electric field on germanium-seeded lateral crystallization of a-Si is studied for the first time and compared to this effect in Ni-induced lateral growth. While the crystallization rate is lower when Ge is used as the nucleation seed and annealing should be done at higher temperatures, filed-aided crystallization shows a similar behavior to that observed for Ni-induced crystallization. Optical microscopy results indicate that grain growth starting from the negative electrode occurs in Si films at annealing temperatures higher than 480°C, while the applied electric field ranges form 200 to 1400V/cm. SEM was also used to confirm the crystallinity of the films.
The Effect of H2 Dilution On Thin Film SiN Deposited by Hot Wire Cvd Using SiH4 and NH3 Gas Mixtures
Authors: Dillon A. C. , Gedvillas L. , Williamson D. L. , Thiesen J. , Perkins J. D. , Mahan A. H. 
Published: April 2011

ABSTRACTThe structure of thin film SiN, deposited by the hot wire chemical vapor deposition (HWCVD) technique using SiH4 and NH3 gas mixtures, has been examined as a function of the amount of H2 dilution of the gas mixture. For NH3/SiH4 gas ratios > 0.5/1, all films are a-SiN:H. While H2 dilution does not change the basic film structure, in that the films are amorphous with all dilutions, H2 dilution does increase the efficiency of NH3 dissociation in the gas phase, and causes a further reduction in the already small amount of N-H bonding in a-SiN:H films deposited by HWCVD. For NH3/SiH4 gas ratios typically <0.5/1 and with high H2 dilution, the first deposition of µc-SiN is demonstrated. X-ray diffraction (XRD) measurements demonstrate that the structure of these films consists of silicon crystallites embedded in an a-SiN:H matrix. An upper limit for N incorporation with the preservation of microcrystallinity was found, beyond which the films again became amorphous. The existence of this limit is explained in terms of structural disorder in the a-SiN:H tissue brought about by N incorporation.
The Effect of Moderate Hydrogen Dilution on Stability and Structure of Amorphous Silicon Deposited by Hot-Wire CVD
Authors: Weber Urban , Schroeder Bernd 
Published: April 2011

ABSTRACTThe effect of moderate hydrogen dilution of the process gas, F(H2)/F(SiH4) = 0 to 3, on the properties of amorphous silicon is discussed for material and solar cells deposited by Hot-Wire CVD. Dielectric properties were obtained from spectroscopic ellipsometry and are related to stability and hydrogen bonding configuration of films deposited with varying hydrogen dilution at different substrate temperatures. The stability was determined by comparing defect densities obtained from photoconductivity spectroscopy in the constant photocurrent mode (CPM) before and after pulsed-light soaking. At low substrate temperatures, which are relevant for the prepara- tion of pin-type solar cells (160-200°C), moderate hydrogen dilution (∼0.3) improves material quality regarding density and network disorder (oscillator bandwidth) as obtained from spectro-scopic ellipsometry, resulting in a higher stability. At higher substrate temperatures (300°C), stability and hydrogen bonding configurations are generally better, but moderate hydrogen dilu-tion already deteriorates these properties compared to material prepared without dilution. The incorporation of Hot-Wire-a-Si:H into pin-type solar cells is also discussed and a good correlation of ellipsometric results with bulk-related properties of solar cell performance is observed. The optimum hydrogen dilution is found to be 0 to 0.3 for i-layer deposition yielding initial efficiencies of up to 8.9% for solar cells entirely fabricated by Hot-Wire CVD.
Effect of CdCl2 Treatment on the Interior of CdTe Crystals
Authors: Price Kent J. 
Published: April 2011

ABSTRACTAn essential processing step in CdTe/CdS polycrystalline solar cells is heat treatment in CdCl2. We present photoluminescence results from single crystals of CdTe that have been exposed to CdCl2 treatments at 387 C similar to those used in actual cell fabrication. Using sub band gap excitation from a tunable diode laser, we probe states in the interior of the crystal. We show that high-purity (99.998 percent) CdCl2 treatment results in the appearance of a 1.45 eV donor-acceptor transition that is likely due to a Cl-Cu center. Low purity (99.7 percent) CdCl2treatment results in the appearance of the 1.45 eV line and a 1.555 eV Cu-related emission. These results indicate that the CdCl2 treatment has an effect on the interior of CdTe grains, in addition to its already well established effect on grain boundaries in polycrystalline CdS/CdTe devices. They also imply that CdCl2 treatment may result in the incorporation of Cu into the CdTe grains. The results will be related to the effects of CdCl2 on polycrystalline CdS/CdTe devices that have been observed by other groups.This work is supported by NREL
Influence of proton irradiation and development of flexible CdTe solar cells on polyimide
Authors: Romeo A. , Bätzner D.L. , Zogg H. , Tiwari A.N. 
Published: April 2011

ABSTRACTCdTe/CdS solar cells of ∼10% efficiency, developed with a vacuum deposition method were irradiated with high-energy protons of different fluences. The Voc and f.f. of irradiated cells increase or decrease depending on the fluence. The normal soda lime glass substrate darkens under the irradiation; therefore low Isc is measured. Measurements suggest that CdTe solar cells are highly stable under proton flux. Flexible and lightweight solar cells were developed in a superstrate configuration on polymer substrates. 8.6 % efficiency cells with Voc∼770 mV and Isc of 20.3 mA/cm2 were achieved.
CdTe Thin Film Solar Cells: The CdS/SnO2 Front Contact
Authors: Fritsche J. , Gunst S. , Thiβen A. , Gegenwart R. , Klein A. , Jaegermann W. 
Published: April 2011

ABSTRACTTin dioxide (SnO2) coated glass is the commonly used substrate for thin film solar cells based on CdTe absorbers. We have investigated the properties of the CdS/SnO2 interface by X-ray and ultraviolet photoelectron spectroscopy. SnO2 coated glass substrates as used for solar cell preparation were cleaned by different procedures such as derinsing, sputtering, heating and annealing in oxygen atmosphere. Different surface properties with a strongly dependent number of defects in the SnO2 band gap are identified. CdS films were deposited stepwise by thermal evaporation to determine the electronic interface properties for different surface preparation conditions. Comparative barrier heights at the CdSSnO2 contact are found for most surface pretreatments. The Fermi level position in these cases is situated in the SnO2 band gap. A different interface behaviour is determined for sputter cleaned SnO2 surfaces, which is attributed to the formation of oxygen vacancies during sputtering and subsequent formation of an interfacial SnOxSy compound.
How do Buffer Layers Affect Solar Cell Performance and Solar Cell Stability?
Authors: von Roedern Bolko 
Published: April 2011

ABSTRACTBuffer layers are commonly used in the optimization of thin-film solar cells. For CuInSe2-and CdTe-based solar cells, multilayer transparent conductors (TCOs, e.g., ZnO or SnO2) are generally used in conjunction with a CdS heterojunction layer. Optimum cell performance is usually found when the TCO layer in contact with the CdS is very resistive or almost insulating. In addition to affecting the open-circuit voltage of a cell, it is commonly reported that buffer layers affect stress-induced degradation and transient phenomena in CdTe- and CuInSe2-based solar cells. In amorphous silicon solar cells, light-induced degradation has a recoverable and a nonrecoverable component too, and the details of the mechanism may depend on the p-type contact layer. Because of the similarity of transients and degradation in dissimilar material systems, it is suggested that degradation and recovery are driven by carriers rather than by diffusing atomic species. The question that must be addressed is why, not how, species diffuse and atomic configurations relax differently in the presence of excess carriers. In this paper, I suggest that the operating conditions of a cell can change the carrier transport properties. Often, excess carriers may enhance the conductance in localized regions (“filaments”) and buffer layers; limiting current flow into such filaments may therefore control the rate and amount of degradation (or recovery).
Laser Light Scattering in-situ Studies on the Growth of Chalcopyrite Thin Films
Authors: Scheer R. , Pietzker Ch. , Bräunig D. 
Published: April 2011

ABSTRACTThe method of diffuse laser light scattering (LLS) has been tested for process monitoring of simultaneous and sequential chalcopyrite film formation. Characteristic LLS features are observed which can be assigned to morphological and optoelectronic film modifications. The surface roughness development as a function of time of CuInS2 and CuInSe2 epilayers grown on Si(111) substrates is monitored. It is found that the critical thickness of a smooth surface without islands depends on the film composition (Cu/(Cu+In) ratio). LLS transients for sequential film formation depict a series of characteristic features which are connected with, e.g., precursor transformation, surfacial sulfurization, and secondary phase transformation.
A Comparative Study of CdS Thin Films Grown by Chemical-Bath Deposition and Close-Spaced Sublimation
Authors: Moutinho H.R. , Albin D. , Yan Y. , Dhere R.G. , Perkins C. , Li X. , Al-Jassim M.M. 
Published: April 2011

ABSTRACTIn this work we study the properties of cadmium sulfide thin films grown by chemicalbath deposition and close-spaced sublimation, on SnO2/borosilicate glass and SnO2/silicon substrates, before and after treatment in vapor CdCl2 at 400°C for 5 minutes. The as-deposited CBD CdS films had cubic structure, poor crystallinity, and high density of planar defects. After the CdCl2 treatment, these films recrystallized to the hexagonal structure, with improved crystallinity and a decrease in the density of planar defects. The as-deposited CSS films had hexagonal structure, better crystallinity, and lower density of planar defects. The main effect of the CdCl2 treatment was a decrease in the intragrain strain in the films. The CBD films had smaller grains and provided a good conformal coverage over the SnO2 films. In contrast to these films, CSS CdS did not have any oxygen or chlorine in its bulk.
Improved Routes to Nanocrystalline Metal Oxide Films for Dye-Sensitised Solar Cells and Related Applications
Authors: O'Hare Iain P. , Govender Kuvasani , O'Brien Paul 
Published: April 2011

ABSTRACTNanoporous metal oxide thin films are currently attracting interest for a wide range of electronic applications, including sensors and dye-sensitised photovoltaic cells. However, limited, and poorly controlled, film fabrication routes represent a key factor impeding the development of such devices. To date, device applications have largely been limited to sol-gelfabricated nanocrystalline films of titanium dioxide (TiO2). Such studies have recently been extended to the application of an alternative film fabrication technique, notably that of chemical bath deposition (CBD), for the growth of zinc oxide (ZnO). One interesting feature of CBDfabricated films of ZnO is that, under specific conditions of supersaturation, highly reticulated layers may be obtained, such an observation suggesting that control of morphology is possible. Thick nanoporous films of ZnO have been deposited, upon conducting glass substrates, under both acidic and alkaline conditions, from a solution containing the metal ion, added acid or base, and either a chelating agent, such as ethylenediamine or triethanolamine, or a buffer, hexamethylenetetraamine (HMT). The deposition rate is controlled by systematic adjustment of both temperature and pH, together with the nature, and relative concentration, of the reactants in the solution (chelating agent or metal ion). The material properties of the resulting films have been characterised through the use of a range of techniques, including Scanning Electron Microscopy (SEM), X-Ray Powder Diffraction (XRD) and Energy Dispersive Analysis by XRays (EDAX), and the results are discussed within the context of the suitability of the deposited films for incorporation within nanocrystalline devices.
Effects of Surface Termination on CuIn1−XGaXSe2 Prepared from Mixed Cu-In-Ga-Se Precursors
Authors: Beck Markus E. , Alleman Jeff , Swartzlander-Guest Amy , Matson Rick , Noufi Rommel 
Published: April 2011

ABSTRACTThin film CuIn(Ga)Se2 samples were prepared by a two-stage method starting from amorphous or nano-crystalline precursor structures. Deposition of individual Cu+Se and In+Se layers as a function of substrate temperature revealed the onset of detectable crystal structures at Tsub = 100°C and Tsub. ≥200°C, respectively. For the quaternary system the formation of CuInSe2 was observed at 400°C and evidence was found for liquid CuxSe assisted growth.Further focus was on surface termination schemes with the objective to enhance the opencircuit voltage. Ga+Se, In+Se, Ga+Se/In+Se, and In+Se/Ga+Se terminating layers with varying amounts of Ga and In are addressed. Schemes studied to date have resulted in an increase in Voc at the expense of short-circuit current. The use of Ga containing termination layers resulted in the formation of large voids in the CIGS which could be explained by the volume changes during formation of the quaternary material and a Cu2Se free surface in these instances.
Reduction of Whisker-Originated Short between W Polymetal and Contact Plug
Authors: Akasaka Yasushi , Suzuki Hiroshi , Yokoyama Yuji , Yasutake Nobuaki , Yasutake Hitomi , Yoshikawa Susumu , Kohyama Yusuke , Ozawa Yoshio , Hieda Katsuhiko , Suguro Kyoichi , Nakanishi Toshihiro 
Published: April 2011

ABSTRACTWhisker-originated short in the self-aligned contact (SAC) W polymetal gate was directly observed for the first time. Short points between gate electrodes and poly-Si plugs in the test structure were identified by emission microscope and cross-sectional TEM samples of those points were made by using focused ion beam (FIB).Whiskers are formed during high-temperature processing such as LP-CVD SiN. We have proposed that NH3 de-oxidation step inserted in the SiN deposition sequence is effective for suppressing whisker growth. [1] In this study it was also confirmed that 600°C NH 3 pre-flow improved leakage current between gate electrode and contact plugs.
Constrained Diffusional Creep in Thin Copper Films
Authors: Weiss D. , Gao H. , Arzt E. 
Published: April 2011

ABSTRACTThe mechanical properties of thin metal films have been investigated for many years. How- ever, the underlying mechanisms are still not fully understood. In this paper we give an overview of our work on thermomechanical properties and microstructure evolution in pure Cu and dilute Cu-Al alloy films. Very clean films were produced by sputtering and annealing under ultra-high vacuum (UHV) conditions. We described stress-temperature curves of pure Cu films with a constrained diffusional creep model from the literature. In Cu-1at.%Al alloy films, Al surface segregation and oxidation led to a “self-passivating” effect. These films showed an increased high- temperature strength because of the suppression of constrained diffusional creep; however, under certain annealing conditions, these films deteriorated due to void growth at grain boundaries.
Dislocation Dynamics Simulations of Dislocation Interactions in Thin Fcc Metal Films
Authors: Pant Prita , Schwarz K.W. , Baker S.P. 
Published: April 2011

ABSTRACTMesoscopic simulations of dislocation interactions in thin, single crystal FCC metal films were carried out. Interactions between threading-misfit and threading-threading dislocation pairs were studied and the strength of the interactions determined. Threading-threading interactions were found to be significantly stronger than threading-misfit interactions. Dislocations with different possible combinations of Burgers vectors were studied under cyclic loading. Only annihilation of dislocations was seen to result in residual dislocation structure after complete unloading. No differences were observed in the nature of threading-misfit interactions in 111 and 001 oriented films.
Observations of Dislocation Motion and Stress Inhomogeneities in a Thin Copper Film
Authors: Balk T. John , Dehm Gerhard , Arzt Eduard 
Published: April 2011

ABSTRACTIn situ transmission electron microscopy has been utilized to study dislocation plasticity in a 200 nm thick copper film. The behavior of dislocations in a [111]-oriented grain was recorded during a thermal cycle. During cooling, it was observed that dislocations were emitted from a grain boundary triple junction in regular intervals of 30°C to 40°C. Subsequent glide occurred on a (111) plane parallel to the film surface, despite the expectation of zero resolved shear stress on such planes. The initial emitted dislocations remained close to the triple junction, avoiding contact with another [111] grain rotated by 17°. Glide into the opposite end of the grain was initiated only after the injection of several additional dislocations, which induced strong curvature in all dislocations near the active triple junction. Post mortem examination of dislocation curvature revealed that an inhomogeneous stress state existed within the grain.
A Kinetic Model for the Strain Relaxation in Heteroepitaxial Thin Film Systems
Authors: Zhang Y.W. , Wang T.C. , Chua S.J. 
Published: April 2011

ABSTRACTA kinetic model is presented to simulate the strain relaxation in the GexSi1−x/Si(100) systems. In the model, the nucleation, propagation and annihilation of threading dislocations, the interaction between threading dislocations and misfit dislocations, and surface roughness are taken into account. The model reproduces a wide range of experimental results. The implications of its predictions on the threading dislocation reduction during the growth processes of the heteoepitaxial thin film systems are discussed.
Misfit Dislocations in Epitaxial Ni/Cu Bilayer and Cu/Ni/Cu Trilayer Thin Films
Authors: Yamamoto Tadashi , Misra Amit , Hoagland Richard G. , Nastasi Mike , Kung Harriet , Hirth John P. 
Published: April 2011

ABSTRACTMisfit dislocations at the interfaces of bilayer (Ni/Cu) and trilayer (Cu/Ni/Cu) thin films were examined by plan-view transmission electron microscopy (TEM). In the bilayers, the spacing of misfit dislocations was measured as a function of Ni layer thickness. The critical thickness, at which misfit dislocations start to appear with the loss of coherency, was found to be between 2 and 5 nm. The spacing of the misfit dislocations decreased with increasing Ni layer thickness and reached a plateau at the thickness of 30 nm. The minimum spacing is observed to be about 20 nm. A g·b analysis of the cross-grid of misfit dislocations revealed 90° Lomer dislocations of the <110>{001} type lying in the (001) interface plane at a relatively large thickness of the Ni layer, but 60° glide dislocations of the <110>{111} type at a relatively small thickness of the Ni layer. In the trilayers, misfit dislocations formed at both interfaces. The spacing of the misfit dislocation is in agreement with that of the bilayers with a similar Ni layer thickness. The misfit dislocation arrays at the two interfaces, having the same line directions, are 60° dislocations with edge components with opposite signs but are displaced with respect to each other in the two different interface planes. This suggests that interactions of the strain fields of the dislocations have a strong influence on their positions at the interface.
Local Microstructure and Stress in Al(Cu) Thin Film Structures Studied by X-Ray Microdiffraction
Authors: Valek B.C. , Tamura N. , Spolenak R. , MacDowell A.A. , Celestre R.S. , Padmore H.A. , Bravman J.C. , Brown W.L. , Batterman B. W. , Patel J. R. 
Published: April 2011

ABSTRACTThe microstructure of materials (grain orientation, grain boundaries, grain size distribution, local strain/stress gradients, defects, …) is very important in defining the electromigration resistance of interconnect lines in modern integrated circuits. Recently, techniques have been developed for using submicrometer focused white and monochromatic x-ray beams at synchrotrons to obtain local orientation and strain information within individual grains of thin film materials. In this work, we use the x-ray microdiffraction beam line (7.3.3) at the Advanced Light Source to map the orientation and local stress variations in passivated Al(Cu) test structures (width: 0.7, 4.1 μm) as well as in Al(Cu) blanket films. The temperature effects on microstructure and stress were studied in those same structures by in-situ orientation and stress mapping during a temperature cycle between 25°C and 345°C. Results show large local variations in the different stress components which significantly depart from their average values obtained by more conventional techniques, yet the average stresses in both cases agree well. Possible reasons for these variations will be discussed.
Plasma Induced Chemical Changes at Silica Surfaces During Pre-Bonding Treatments
Authors: Hansen Darren M. , Albaugh C.E. , Moran Peter D. , Kuech T. F. 
Published: April 2011

ABSTRACTPlasma-treated and DI H2O rinsed oxide layers are commonly used in wafer bonding applications. Borosilicate glass (BSG) layers deposited by low-pressure chemical vapor deposition (LPCVD) treated with an O2 plasma in reactive ion etching (RIE) mode at 0.6 W/cm2 and rinsed with DI H2O readily bond to GaAs and Si. The chemical role of this pre-bonding treatment was investigated using attenuated total reflection Fourier transform infrared (ATR- FTIR) spectroscopy. The peak intensities for both the Si-O and B-O absorbance bands decreased in intensity as a result the plasma treatment consistent with the uniform sputter etching of BSG. The effect of changing the total plasma treatment time was investigated in terms of the total amount of material removed. Polarization-dependent ATR-FTIR revealed that the H2O/OH absorbance bands decreased in peak intensity with the OH groups preferentially oriented perpendicular to the sample surface after the plasma treatment. The subsequent DI H2O rinse restores the water to the surface while changing the surface BSG composition. ATR-FTIR studies suggest that for oxide compositions greater than 10 mole % B2O3, the top 4 nm of B2O3 was removed or leached from the oxide layer during the DI H2O rinse.
A Novel Method of Fabricating SiC-On-Insulator Substrates for Use in MEMS
Authors: Kuo Hung-I , Zorman Christian , Mehregany Mehran 
Published: April 2011

ABSTRACTThis paper reports on a novel, bonding-free method to fabricate silicon carbide-on-insulator (SiCOI) substrates. The process bypasses wafer bonding by using a high deposition rate polysilicon process in conjunction with wet chemical etching to produce wafer-thick polysilicon layers that serve as substrates for the SiCOI structures. Because wafer bonding is not used, insulators of various material types and thickness can be used. Using this method, transfer percentages over 99% are readily achievable. Various applications could benefit from this technology, including high temperature SiC-based microelectromechanical systems (MEMS) and SiC electronic devices.