bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Pattern and Emissivity Insensitive Dopant Activation and Silicide Contact Formation Annealing in a Hot Wall Rapid Thermal Annealing System
Authors: Yoo Woo Sik 
Published: February 2020

Rapid thermal annealing (RTA) enabled shallow junction formation requires very short time annealing at high temperatures for low thermal budget. RTA is typically done by lamp-based radiant heating. Radiant power from lamp arrays is close-loop controlled to execute the temperature of the Si wafer as programmed. The increase of annealing temperature and the decrease of annealing time are generally required for more aggressive device scaling. However, the use of non-equilibrium radiant heat sources (photon energy from lamp arrays) makes the heating process sensitive to the optical properties of the Si wafers.
Local temperature non-uniformity during RTA is considered an important contributor for within-die process variations which cause significant problems for advanced complimentary metal-oxide-semiconductor (CMOS) device manufacturing. RTA-induced variations strongly depend on circuit layout patterns and optical properties of exposed materials on the surface of the Si wafers. This phenomenon is often referred to as “pattern effect” known from the early days of RTA introduction in the semiconductor industry.
In efforts to reduce the “pattern effect”, various approaches have been proposed and implemented in device manufacturing. Shielding device patterns from the radiant heat source is a common approach, having limited success. It is done by either placing a dummy wafer on the pattern side of the Si wafer or backside heating. One other common approach is to homogenize the optical properties of the pattern side of Si wafer by either adding an optical absorption layer or dummy patterns. A differential thermal energy control technique is also proposed for pattern effect suppression. Non-radiative heating techniques have been proposed and demonstrated effectiveness of this “pattern effect” suppression.
In this paper, various silicide contact formations on implanted single crystalline Si in source/drain region and implanted poly-Si in gate region were studied over wide ranges of RTA temperature and time using a hot wall RTA system which uses mainly natural convection and conduction through ambient gas. Dopant profiles of the silicide and doped Si after silicidation in the hot wall RTA system were characterized. Proposed possible silicide formation and dopant diffusion mechanisms are discussed. Differences between radiant heating and non-radiant heating on the silicide formation and dopant profiles are compared. The pattern and emissivity insensitive dopant activation and silicide contact formation annealing results will be introduced and potential applications of the hot wall RTA technique in advanced CMOS devices will be proposed.
Fabrication of Graphene/Porous Silicon Nitride Material for Field-Effect Transistors
Authors: Ge Daohan , Qian Dongliang , Chen Guanggui , Zhang Liqiang , Ren Naifei 
Published: February 2020

Graphene, a novel material, has attracted significant attention due to its distinctive band structure and fascinating physical properties. These unusual properties have caused the emergence of tantalizing potential applications, ranging from field effect transistors to chemical and biochemical sensors. Due to their low mass, high quality factor, and good optical properties, silicon nitride micromembrane resonators are widely used in force and mass sensing applications. However, for practical graphene devices, many problems need to be solved, such as morphology control, interfacial engineering between graphene and silicon nitride substrate.
Here, we transfer graphene to the silicon nitride substrates with two different morphologies (holes and grooves). Monolayer graphene film can be prepared on the copper via chemical vapor deposition (CVD) process as previous reported method. Next step is transfering graphene to the substrate. The morphologies of graphene on the substrate were obtained by SEM (Fig. 1a,b). As shown , the graphene in the hole and groove is not suspended, but directly exposed to the substrate. The graphene’s Raman information in hole is achieved by the micro-Raman spectrometer (Fig. 1c), which shows good quality . Such hybrid Graphene/Porous Silicon Nitride structures can be used to fabricate field-effect transistors.

Figure 1
Characterization of GaN Device Interconnect Metallization Reliability
Authors: Kilgore Steve , Hill Darrell , Green Bruce 
Published: February 2020

The gallium nitride (GaN) semiconductor market continues to rapidly expand because GaN device technology offers considerable performance advantages compared to gallium arsenide (GaAs) and silicon (Si) devices. GaN has inherently higher breakdown field strength, charge density, and electron velocity at high voltage. These material properties permit GaN devices to operate at higher bias voltages and higher current densities than GaAs and Si devices. Commercial applications can utilize RF power amplifiers at higher frequencies (> 2 GHz) and higher power (> 400 W) in a single packaged GaN transistor. However, this higher power density operation requires examination of the degradation and reliability of these GaN devices at elevated temperatures. The evaporation deposited gold interconnect metallization of GaN HFET devices was stressed to evaluate its high temperature reliability. Optimized test structures were designed to assess the electromigration wear-out in evaporated deposited Au films encapsulated with SiN passivation. A current density of 1 MA/cm2 with oven stress temperatures in excess of 335 °C was applied to large quantities of Au interconnects. The selected failure criteria of 50% resistance increase yielded Au lifetime distributions that followed typical log-normal electromigration failure statistics. All log-normal sigma values were less than 0.6 which is an indication of a mono-modal failure mechanism. The activation energy value was measured from multiple stress temperatures. Physical characterization of the evaporated Au interconnect structures are discussed along with a comparison to electroplated Au interconnects.
(Invited) Gallium Oxide Based Materials and Devices
Authors: Jena Debdeep 
Published: February 2020

The availability of high-quality bulk crystals of beta-gallium oxide (Ga2O3) has provided a shot-in-the-arm for extending electronic device technologies beyond the currently popular SiC and GaN. Though for high-voltage electronics Ga2O3 has a much larger bandgap (~4.6 eV) than GaN, it is still smaller than AlN and diamond. The thermal conductivity of Ga2O3 is also abysmally low compared to AlN and diamond. What then is the potential of Ga2O3 for electronic device technologies? Though it is impossible to predict, I will present my opinions on what aspects of this new material can provide significant advantages over other material systems for electronic and photonic devices. I will then provide expermental data and theory and modeling on the electronic, optical, and thermal properties of the Ga2O3 material system that has been investigated in my group. I will also present a summary of our MBE-based epitaxial growth of Ga2O3 based materials, and device results.
Electrodeposition of Doped ZnO Layer Using Three Different Dopant (Properties and structure)
Authors: Saeed Mahfouz Ali 
Published: February 2020

Zinc oxide (ZnO) is a conductive oxide, which serves as the n-type semiconductor. Furthermore, ZnO has other favorable properties including high electron mobility, stability, and good transparency.
We were introduced the new electrolyte composition (previous conferences), which is far more dilute than systems that had been previously described, and which yields much improved CIGS films.
In this work we introduce ZnO layer doped with either indium or gallium or Aluminum were electrodeposited potentiostatically at 75oC from aqueous solutions containing Zn(NO3)2 and either InCl3 or GaCl3 or Al(NO3)3. Undoped ZnO was used as substrate. The films were used for the preparation of PN-junctions based on electrodeposited CuGaInSe2 thin solid films. CIGS and CIGSS functional photovoltaic devices, based entirely on electroplating.
Complete electrodeposited devices were generated and tested exhibiting efficiencies ranging from 2 to 6% with quantum efficiency exceeding 0.6. This is the first that such a comprehensive process had been described, leading the way to a potential fabrication of an entire device using an electrochemical route, enabling effective manufacturing integration and scaling.
The effects of mass transport on the deposit composition and its adhesion to the substrate are discussed. Sample polarization curves at different electrode rotation rates are provided for the three different doped ZnO layer (figure 1).
The final composition, oxides contents, crystallography and oxides effects on the deposit quality were determined using Energy-dispersive X-ray spectroscopy technique (EDS) and XRD (figure2). Profilometer was used to determine the deposit thickness.

References

[1] Hossain, F. Nishii, J. Takagi, S. Sugihara, T. Ohtomo, A. Fukumura, T. Koinuma, H. Ohno, H. Kawasaki, M.,
Physica E. 21 (2004) 911.
[2] Rousset, J. Saucedo, E. Lincot, D. Chemistry of Materials 21 (2009) 534.978-
[3] Chikoidze, E. Nolan, M. Modreanu, M. Sallet, V. Galtier, P. Thin Solid Films 518 (2008) 8146.
[4] Machado, G. Guerra, D. Leinen, J. Ramos-Barrado, R. Marotti, A.Dalchiele, Thin Solid Films 490 (2005) 124 –
131.

Figure 1
Application of TiO2 Nanowires As Wide Gap Semiconductor Material in the Heterogeneous Catalysis of Benzophenone-4
Authors: Díaz Francisco , Márquez Francisco , Soto-Vázquez Loraine , Rivera Keila , Rolón Frankie 
Published: February 2020

Water pollution has emerged as a primary concern in environmental issues due to the consumption of pharmaceuticals and personal care products which are chemical substances resilient to traditional remediation methods. The heterogeneous catalysis of organic pollutants has been considered as a promising decontamination method because of its capability to mineralize recalcitrant pollutants at a lower cost than others. TiO2 nanowires (TiO2NWs) were synthesized and characterized, and its catalytic activity was proved using benzophenone-4 (BP-4) as a target organic pollutant. The TiO2NWs were synthesized following a hydrothermal method using TiCl4 as the precursor. A pure rutile crystalline structure was determined by X-ray diffraction and Raman spectroscopy measurements. Also with a high band gap energy was determined by UV-Vis spectroscopy. Elongated and highly branched structures were obtained according to electron microscopy images. During the photodegradation experiments a high catalytic activity was observed since 90% of photodegradation was achieved in 180 minutes of reaction. Optimal experimental conditions were determined using a catalyst loading of 1.2 gL-1 at pH 5 when BP-4 initial concentration is 20 µM. When radiation and oxygen sources are not present, the reaction is negligible, and therefore no photodegradation occurs. This suggests that BP-4 can not be degraded in short times by photolysis, catalysis or under anoxic conditions. In conclusion, we successfully synthesized and characterized TiO2NWs and a high photocatalytic activity was showed with degradation rates of 90% of BP-4 in a relatively short period of time, suggesting that this process is a viable option to clean polluted water sources. The photoproducts of BP-4 should be characterized to confirm this process as an environmentally remediation solution.
(Invited) Properties and Applications of 2-Dimensional Layered Materials
Authors: Duesberg Georg S. 
Published: February 2020

Two-dimensional transition metal dichalcogenides (TMDs) have moved to the foreground of the research community owing to their fascinating properties which make them of great interest for both fundamental studies and emerging applications. Thermally assisted conversion (TAC) of predeposited transition metal films and Chemical vapour deposition (CVD) show great promise for the scalable and industry-compatible synthesis of these materials[1]. Here we outline the production of an assortment of TMDs by TAC and CVD, and demonstrate their high-quality using an array of characterization techniques including Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy.
The potential of TMDs films for various applications in the realm of electronics and energy will be discussed. It is possible to structure and electrically address the films yielding simple devices such as transistors, diodes and sensors. The fabrication of high-performance gas sensors, with room temperature detection limits in the ppb range for NH3 will be described in detail[2]. The fabrication of large-scale heterojunction diodes, formed by transferring n-type MoS2 onto p-type Si, will be outlined. [3] Additionally, a novel catalyst platform for the hydrogen evolution reaction (HER), consisting of MoS2 (or other TMDs) grown directly on top of a carbon electrode, will be discussed[4].
[1] "Controlled Synthesis of Transition Metal Dichalcogenide Thin Films for Electronic Applications", Riley Gatensby, Niall McEvoy, Kangho Lee, Toby Hallam, Nina C. Berner, Ehsan Rezvani, Sinéad Winters, Maria O'Brien, Georg S. Duesberg, Applied Surface Science, 297, 139-146, (2014)
[2] "High Performance Sensors Based on Molybdenum Disulfide Thin Films", Kangho Lee, Riley Gatensby, Niall McEvoy, Toby Hallam, Georg S. Duesberg, Advanced Materials, 25(46), 6699-6702, (2013)
[3] "Heterojunction Hybrid Devices from Vapor Phase Grown MoS2", Chanyoung Yim, Maria O'Brien, Niall McEvoy, Sarah Riazimehr, Heiko Schäfer-Eberwein, Andreas Bablich, Ravinder Pawar, Giuseppe Iannaccone, Clive Downing, Gianluca Fiori, Max C. Lemme & Georg S. Duesberg, Scientific Reports, 4, 5458, (2014)
[4] "Molybdenum disulfide/pyrolytic carbon hybrid electrodes for scalable hydrogen evolution", Hugo Nolan, Niall McEvoy, Maria O'Brien, Nina C. Berner, Chanyoung Yim, Toby Hallam, Aidan R. McDonald and Georg S. Duesberg, Nanoscale, 6, 8185-8191, (2014)
(Invited) Controlling the Band Structure of Black Phosphorus
Authors: Kim Keun Su 
Published: February 2020

Two-dimensional (2D) atomic crystals have emerged as a class of materials that may impact our future electronics technology [1]. A key issue is controlling their electronic state to overcome the limit of natural properties. In this regard, there are rapidly growing interests in black phosphorus, a layered material consisting of 2D phosphorene layers. The low-energy band structure of black phosphorus has been widely predicted to be tunable by external perturbations, such as applied strain and electric field [2]. In this talk, I will introduce our recent angle-resolved photoemission spectroscopy studies on the tunable band gap of black phosphorus. By the in-situdeposition of alkali-metal atoms on the surface of black phosphorus, we found that the vertical electric field from dopants modulates the band gap, and changes the material from a narrow-gap semiconductor to a band-overlapped semimetal [3]. At the critical density of this semiconductor-semimetal transition, the material becomes a 2D Dirac semimetal, whose band dispersion is highly anisotropic, linear in armchair and quadratic in zigzag directions [3].
[1] E. S. Reich, Nature 506, 19 (2014).
[2] H. O. H. Churchill and P. Jarillo-Herrero, Nature Nanotech. 9, 330 (2014).
[3] J. Kim, S. S. Baek, S. H. Ryu, Y. Sohn, S. Park, B. G. Park, J. D. Denlinger, Y. Yi, H. J. Choi, and K. S. Kim, Science 349, 723 (2015).
(Invited) Interplay of Charge and Lattice Distortion in Few Layers of Transition Metal Dichalcogenides
Authors: Chou Mei-Yin 
Published: February 2020

Transition metal dichacogenides have layered structures in the bulk and exhibit various characteristics ranging from normal semiconductors to charge density waves (CDW) to magnetism. Current fabrication techniques have made it possible to extract a single composite monolayer in the laboratory and to measure the physical properties of this truly two-dimensional system. It is also possible to vary the charge carrier density by external gating methods, adding another control parameter to the monolayer configurations. Given these new possibilities, we have performed first-principles calculations to explore the connections among charging, lattice distortion, electronic properties, and charge density waves. In particular, we will report the results for various charge density wave systems in two dimensions and explain the mechanism of forming these phases. In addition, we have also found that substantial hole doping can give rise to a CDW-to-superconductor (SC) phase transition in VSe2.
*In collaboration with Yang-hao Chan and Chih-Piao Chuu.
Passivating Defects and Tunning the Schottky Barrier for Two-Dimensional Semiconductors
Authors: Liu Yuanyue , Stradins Pauls , Wei Suhuai 
Published: February 2020

Two-dimensional semiconductors show great promise for next-generation (opto)electronics, yet a number of issues have to solved before realizing their full potential. Here by using atomistic theory, we show that: (i) The harmful electronic states induced by chalcogen vacancies can be removed by chemisorption of oxygen molecules. This reaction occurs with a barrier that correlates with the cohesive energy of the semiconductor. The repair of the electronic structure originates from the isovalence between O2 and X when bonded with metal. Based on these findings, we propose an approach to improve the performance of 2D semiconductors by using O2 to passivate the defects. [1] (ii) The problem of large and untunnable Schottky barrier at the metal–semiconductor interface can be solved with new electrode materials. [2]

[1] Y. Liu, P. Stradins, S. Wei, Angew. Chem. Int. Ed. 2015, DOI: 10.1002/anie.201508828; [2] Y. Liu, P. Stradins, S. Wei, submitted
Microstructural Modelling and Simulation of Mixed Conducting SOFC Cathodes
Authors: Joos Jochen , Carraro Thomas , Weber André , Ivers-Tiffée Ellen 
Published: February 2020

Chemical composition and microstructure determine the electrochemical performance characteristics of mixed ionic-electronic conducting (MIEC) cathodes. This work focuses on the performance simulation and evaluation of porous LSCF cathodes with the same nominal chemical composition, but with microstructures differing in grain size, porosity and tortuosity. A numerical tool is presented, which mimics the sintering process, thus generating realistic (synthetic) 3D microstructures. This tool was validated by comparing microstructure parameters of the generated structures with those derived from “real” cathodes, reconstructed via FIB-tomography.
Together with adequate performance models [1, 2], this approach allows to decouple the influence of material composition and microstructure on performance. It enables us to analyze microstructure development at different sintering parameters (temperature or time). Thus, this tool provides guidelines for designing high-performance cathodes (e.g., ideal material fractions, cathode thickness, etc.).
References
[1] T. Carraro, J. Joos, B. Rüger, A. Weber, E. Ivers-Tiffée, Electrochim. Acta 77, p. 315 (2012)
[2] S. Adler, J. Lane, B. Steele, J. Electrochem. Soc. 143, p. 3554 (1996)

Figure 1
Carbon and Redox Tolerant Infiltrated Oxide Fuel-Electrodes for Solid Oxide Cells
Authors: Skafte Theis Løye , Sudireddy Bhaskar Reddy , Blennow Peter , Graves Christopher 
Published: February 2020

To solve the current issues of coking and redox instability related to the presence of nickel in conventional fuel electrodes in solid oxide cells (SOCs), porous Ce0.9Gd0.1O1.95 (CGO) electrodes were studied using symmetric cells. These electrodes showed low polarization resistance (Rp) due to high electrocatalytic activity, but high ohmic resistance (Rs) due to low electronic conductivity. When infiltrated with Sr0.99Fe0.75Mo0.25O3-δ (SFM) aqueous precursor solution and subsequently calcined at low temperatures (<1100 °C), the electronic conductivity was enhanced, due to a mixture of phases, primarily consisting of SFM, SrFeO3 and the highly electronically conducting SrMoO3 impurity phase. However, Rp of the cells increased, which is likely because the infiltrated material is less electrocatalytically active and was partly blocking the reaction sites. The electrocatalytic activity could be regained by infiltrating nano-sized CGO or NiCGO (10 wt.% Ni relative to CGO) on top of the SFM, while still sustaining the high electronic conductivity. Compared with the porous CGO electrodes, the electrode performance was greatly improved; at 800 °C in H2/H2O 83 %/17 %, RS of the electrodes decreased from ~0.26 Ω·cm2 to close to 0 Ω·cm2 and RP was restored to 0.03 +/- 0.01 Ω·cm2. Similar performance improvement was observed at 650 °C. Thus, performance comparable to, or better than, state-of-the-art fuel electrodes has been achieved. Upon exposure to a fuel gas of 50 %/50 % CO/CO2 at 750 °C, Rs of the cells was largely unaffected while Rp increased by a factor of 2-4 compared with Rs and Rp measured in 50 %/50 % H2/H2O. The Ni containing cells coked when the CO/CO2-ratio was raised above the carbon deposition equilibrium, while none of the non-nickel cells coked or showed signs of intolerance to a CO/CO2-atmosphere (see figure). Stability towards redox cycles and variations in oxygen partial pressure of the infiltrated cells was also proven.
Figure: (a) RS and (b) single electrode RP of three different cell types for 15 h in CO:CO2 90:10 at 750 °C (above the carbon deposition threshold). The NiCGO and SFM is infiltrated into the plain CGO electrode. The inserts on the right are top-down images of the cells after testing.

Figure 1
(Invited) An Atomically Precise Oxygen Evolution Catalyst
Authors: Kauffman Douglas R. 
Published: February 2020

The O2 evolution reaction (OER) is an important anodic process for many aqueous electrochemical applications, including H2 evolution from water and CO2 reduction. Precious metals like Iridium, Ruthenium and/or Platinum are traditionally-used electrochemical anodes because they can efficiently oxidize H2O into O2 with high catalytic activity and good long term stability. However, recent efforts have tried to replace expensive precious-metal anodes with inexpensive and earth-abundant materials. Ni-based materials are promising replacements for precious metal-based OER catalysts because they show high activity and good long-stability. Unfortunately, the literature contains some debate as to the nature of the catalytic reaction center in Ni-based materials. This uncertainty stems from typical catalyst samples containing heterogeneous particle sizes and surface structures, and the literature contains a wide range of reported reaction rates and rate determining steps. My talk describes a combination of experimental and computational techniques to characterize the OER chemistry at an atomically-precise organometallic nickel complex. Single-crystal X-ray diffraction identified the catalyst’s crystal structure as a hexagonal “tiara-like” Ni6(PET) structure (PET = phenylethyl thiol). Laboratory and synchrotron-based X-ray spectroscopies were used to characterize the electronic structure of the Ni6(PET)12 complex (PET = phenylethylthiol). Electrocatalytic testing showed that Ni6(PET)12 outperformed bulk NiO and Pt, and that it had comparable OER performance to that of Ir. Density functional theory (DFT) was used to model the OER at a realistic Ni6(SCH3)12 models to determined Gibbs free energy changes (ΔG) associated OER steps. Computationally predicted potential determining steps and OER onset potentials were in excellent agreement with experimentally-determined values. Interestingly, DFT results suggest subtle changes in adsorbate binding configuration can drastically alter the OER onset potentials. Our results highlight how atomically-precise nanocatalysts can facilitate the development of difficult-to-obtain structure-property relationships because they allow joint experimental and computational studies on nearly identical systems.