bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Advance of Dye-Sensitized Solar Cells with Organic Dyes
Authors: Murakami Takurou N , Koumura Nagatoshi 
Published: February 2020

Dye-sensitized solar cells (DSSCs) have the potential difference between the reduction potential of the dye cation and the redox potential of electrolyte. The cobalt complex redox (Co-redox) electrolyte with the deeper redox potential is one of the candidate to avoid the energy loss for dye regeneration. However, Co-redox electrolyte could induce the fast recombination reaction at the interface between the TiO2 and the electrolyte. The recombination reaction is the reduction reaction of the redox couple with the injected electron in TiO2 and will be the causes of decreasing the open circuit voltage (V
oc). To prevent the recombination reaction, the dyes may play important role as the recombination blocker on the TiO2 surfaces. For the reason, we studied first the effects of steric hindrance of the donor and the π-linker groups in donor-π-linker-acceptors (D-π-As) structured organic dyes on the recombination reaction. The steric hindrance at the donor part in the dye structure reduced the recombination reaction and increased the V
oc of the DSSCs. Conversely, the small steric hindrance at the π-linker groups showed the less recombination reaction because of the higher dye coverage on the TiO2 surface. Furthermore, we studied the effects of the type of donor structure in dye structure on the DSSC performance, and compared the dyes with carbazole (MK-1), coumarin (MK-31), and triphenylamine (MK-88) and N-phenyl-carbazole (MK-90) as the typical donor structure. It found that the triphenylamine can block the recombination reaction due to the steric hindrance of the rotatable phenyl groups.
We also studied the stability of the DSSCs with organic dyes. The binding strength between the dye and the TiO2 surface may affect the heat stability of the DSSCs. Carboxylic acids have generally been used as the anchoring groups for the adsorption of dyes on TiO2 surfaces. However, a phosphonic acid anchor is expected to make more stable bonding to the TiO2 surface because of its tridentate binding capability. In this study, we developed a new carbazole dye that employed a phosphonic acid anchor (MK-94) and studied the effects of the dye anchoring group on the heat stability of DSSCs at 85 °C by comparing MK-94 and MK-2 (a carbazole dye with a carboxylic acid anchoring group). In the initial, the DSSC with MK-94 exhibited a lower short circuit current (J
sc) but a higher Voc than MK-2. After the heat stressing, both dyes showed the decreases in J
sc and V
oc but these were suppressed with MK-94. The drop of the power conversion efficiency (PCE) with MK-94 was kept within 6% after 504 h of heating. The phosphonic acid anchor was effective in extending the long-term heat stability of the DSSCs.
(Invited) Surface Passivation of High-k Dielectric Materials on Diamond Thin Films
Authors: Kovi Kiran Kumar , Majdi Saman , Gabrysch Markus , Suntornwipat Nattakarn , Isberg Jan 
Published: February 2020

Single-crystalline CVD diamond films have excellent electrical and material properties with potential applications in high power, high voltage and high frequency applications that are out of reach for conventional semiconductor materials. For realization of efficient devices (e.g. MOSFET), finding a suitable dielectric is essential to improve the reliability and electrical performance of devices. In the current study, we present results from surface passivation studies by high-k dielectric materials such as aluminum oxide and hafnium oxide deposited by ALD on intrinsic and boron doped diamond substrates. The hole transport properties in the intrinsic diamond films were evaluated and compared to unpassivated films using the lateral time-of-flight technique.
Also, for the advancement of diamond-based electronic devices, the fabrication of MOSFET is crucial as this device finds applications in numerous fields of power electronics and high frequency systems. The MOS capacitor structure which forms the basic building block of the MOSFET is discussed. Inversion phenomenon crucial for the operation of MOSFET observed for the first time in boron doped diamond will be discussed.
(Invited) Defects and Dopants in Silicon and Germanium Nanowires
Authors: Fanciulli Marco , Belli Matteo , Paleari Stefano , Lamperti Alessio , Molle Alessandro , Sironi Mauro , Pizio Antonio 
Published: February 2020

Several architectures for ultra-scaled devices targeting classical and quantum information processing as well as chemical sensing rely on silicon and germanium nanowires (SiNWs, GeNWs). Despite the efforts in the preparation and characterization of these nanostructures some fundamental issues remain relatively unexplored. In particular the investigation of defects at the interface between the semiconductor and its oxide or other semiconductors or oxides in core-shell structures represent an important challenge, as the NW diameter reduces and the surface-to-volume ratio increases [1,2]. The current experimental data and understanding of the n-type doping of silicon and germanium nanowires produced by different methods will be reviewed. The role of hydrogen and defects at the interface between the semiconductor and its oxide [3-5] in the donor de-activation mechanisms, and the effect of the confinement and dielectric mismatch in determining the donor electronic wave function will be discussed. The implications of the differences between the electronic properties of interfacial defects in silicon and germanium with their respective oxides will be also addressed.
References:
[1] V. Schmidt, S. Senz, and U. Gösele, Appl. Phys. A. 86, 187 (2007)
[2] M. T. Björk, H. Schmid, J. Knoch, H. Riel and W. Riess, Nature Nanotech. 4, 103 (2009)
[3] M. Fanciulli, A. Vellei, C. Canevali et al., Nanosci. Nanotechnol. Lett. 3, 568 (2011)
[4] M. Fanciulli, A. Molle, S. Baldovino, A. Vellei, Microelectronic Engineering 88, 1482 (2011)
[5] S. Paleari, S. Baldovino, A. Molle, and M. Fanciulli, Phys. Rev. Lett. 110, 206101 (2013)
(Invited) Novel Selector and 3D RRAM Development for High Density Non-Volatile Memory
Authors: Yang Hongxin , Tan Chun Chia , He Wei , Li Minghua , Jiang Yu , Yang Yi 
Published: February 2020

The development of a higher density non-volatile memory with the 3D vertical resistive random access memory (VRRAM) has attracted great interest from the industries. However, VRRAM currently faces the challenges in selecting the specific cell due to a large number of leakage paths, and fabrication process difficulties. In order to eliminate the sneak path and reduce the power consumption, we have developed a novel selector based on doped chalcogenide material. This novel selector shows nearly ideal selector performances with >107 on/off ratio, 0.2 V holding voltage, 10 pA off-state leakage current, sharp on-switch slope of 7 mV/dec, <10 ns turn on speed, >109 endurance, >1.6 MA/cm2 on current density. To investigate the VRRAM fabrication process, we have developed a process flow to fabricate VRRAM and demonstrated a single level sidewall TaOx based VRRAM device. These VRRAM devices can work properly and its switching performance is independent on the thickness of the switching material. Beside the novel selector and VRRAM integration investigation, we have also proposed a transistor-based novel VRRAM (TB-RRAM) architecture. By forming the RRAM cells and transistors at different layer simultaneously, the fabrication cost related to the lithography, etch and deposition can be greatly reduced. Furthermore, with transistor as RRAM selector, better read/write endurance and reliability is expected and it is believed to be industry friendly because of the similar architecture of 3D NAND.
(Invited) Excellent Wetting Behavior of Yttria on 2D Materials
Authors: Addou Rafik , Batzill Matthias , Wallace Robert M 
Published: February 2020

A high quality yttrium oxide (yttria, Y2O3) dielectric has been grown on different carbon derivatives materials (carbon nanotubes, exfoliated graphene, chemical vapor deposition graphene).1-5 This opens the possibility to use such dielectric for the fabrication of graphene devices.4-5 In this talk, the good wettability of Y2O3 on graphene is demonstrated using various surface science methods. Furthermore, the favorable wetting behavior of yttria is exploited as an effective seeding layer for atomic layer deposition of Al2O3 on graphene.6 Moreover, we investigated the interface between Y2O3 and the transition metal dichalcogenide MoS2 as well as on highly ordered pyrolytic graphite (HOPG). The growth of the yttria film was monitored in-situ by monochromatic X-ray photoelectron spectroscopy and scanning tunneling microscopy (XPS and STM). Depositing yttrium metal results in a chemical interaction between the adlayer and the substrate. However, no indication of chemical interaction was detected for the Y2O3 growth, formed by evaporating yttrium in background O2 environment. This is due to the initial formation of Y-O bonds, before the weak Y-MoS2 and Y-C interaction occurs. The STM results indicate the formation of a uniform dielectric film on both MoS2 and HOPG surfaces, confirming the previous findings on graphene. In conclusions, our results reveal that the underlying MoS2and graphene remains intact following yttria seed deposition. Photoemission measurements of the graphene/oxide contacts indicate n-type doping of graphene with different doping levels caused by the charge transfer at the interfaces.
This work was supported in part by the Southwest Academy on Nanoelectronics sponsored by the Nanoelectronic Research Initiative.
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[1] R. Addou, A. Dahal, and M. Batzill Growth of a Two-Dimensional Dielectric Monolayer on Quasi-Freestanding Graphene. Nature Nanotechnol. 8, 41-45 (2013).
[2] A. Dahal, H. Coy-Diaz H, R. Addou, J. Lallo, E. Sutter, and M. Batzill Preparation and Characterization of Ni(111)/Graphene/Y2O3(111) Heterostructures. J. Appl. Phys. 113, 194305 (2013).
[3] A. Dahal, R. Addou, H. Coy-Diaz, J. Lallo, and M. Batzill. Charge Doping of Graphene in Metal/Graphene/Dielectric Sandwich Structure Evaluated by C-1s Core Level Photoemission Spectroscopy. APL Mater. 1, 042107 (2013).
[4] H. Xu, Z. Zhang, Z. Wang, S. Wang, X. Liang, and L. M. Peng Quantum capacitance limited vertical scaling of graphene field- effect transistor. ACS Nano 5, 2340–2347 (2011).
[5] H. Xu, Z. Zhang, H. Xu, Z. Wang, S. Wang, and L. M. Peng Top-gated graphene field-effect transistors with high normalized transconductance and designable Dirac point voltage. ACS Nano 5, 5031–5037 (2011).
[6] A. Dahal, R. Addou, A. Azcatl, H. Coy-Diaz, N. Lu, X. Peng, F. de Dios, J. Kim, M. J. Kim, R. M. Wallace, and M. Batzill. Seeding Atomic Layer Deposition of Alumina on Graphene with Yttria. ACS Appl. Mater. Interfaces 7, 2082-2087 (2015).
Accelerating Effect of Additives in Damascene Electrodeposition
Authors: Kitahara Toshiya , Kaneko Yutaka 
Published: February 2020

The void-free filling in damascene electrodeposition strongly depends upon the accelerating effect of additive agents. SPS is commonly used accelerator which works in the presence of cuprous and chloride ion. Although several models have been reported to explain the effect of SPS, the precise mechanism of acceleration has not clearly been understood.
Chloride ion also has an accelerating effect through the electron bridge as reported by Nagy et. al. [1]. The bottom-up filling in damascene electrodeposition is expected to be achieved by the accelerating effects of SPS and chloride ion in combination with the suppressing effect of PEG around the via opening. Recently, Kondo et. al.studied the detailed mechanism of acceleration of SPS in relation to the distribution of cuprous ion . They also studied the dependence of the acceleration on the feature size, especially, the width of the trenches [4]. They measured the distribution of cuprous ion using the rotating ring disk technique and discussed that the filling process can be explained in terms of the cuprous ion distribution.
The purpose of the present work is to study the effects of chloride ion and SPS paying attention to the distribution of cuprous ion to clarify the mechanism of acceleration. We first studied the dependence of the current density on the width of the trench in the presence of chloride ion . The acceleration effect due to the electron bridge is taken into account.
The simulation system and additive modeling are the same as those used in our previous works. The system is a two dimensional square lattice and the Cu deposition is simulated by the Kinetic Monte Carlo (KMC) method. The electrode consists of through-mask trench. The basic reactions are
Cu2+ + e- → Cu+ (1)
Cu+ + e- → Cu (2)

The rate constant of reaction (2) is about 1000 times larger than that of reaction (1). Therefore, reaction (1) is the rate determining step [5]. Chloride ions have the effect of accelerating reaction (1) due to the electron bridge, which leads to the overall acceleration of Cu deposition. We have performed a series of KMC simulations of trench filling for different values of the width of the trench.
It is shown that for the small system (the width is much smaller than 1μm) the current density increases as the trench width becomes small. This is consistent with the experimental results. For the trench width ~ 10μm, however, the difference in the current density becomes small as the system becomes large. These results are explained by the distribution of cupric and cuprous ions. The mechanism of acceleration is discussed from the simulation data.
References
[1] Z.Nagy; J.Electrochem.Soc. 142, L87 (1995).
[2] K.Kondo, T.Matsumoto, K.Watanabe; J.Electrochem.Soc.151,C250 (2004).
[3] K.Kondo, T.Nakamura, N.Okamoto; J.Appl.Electrochem. 39, 1789 (2009).
[4] K.Kondo, H.Kouta, M.Yokoi, N.Okamoto, T.Saito and T.Hayashi; Electrochem.
Lett. 3 (4) D3 (2014).
[5] N.Tantavichet, M.D.Pritzker; J. Electrochem. Soc., 150, C665 (2003).
Impact of Accelerator Decomposition Products to the Stability of TSV Filling Processes
Authors: Rohde Dirk , Haubner Kinga , Jäger Cornelia , Kirbs Andreas , Pölleth Manuel , Gaida Josef , Palm Jens 
Published: February 2020

Filling of though silicon vias (TSV) with ECD copper is an important process step to realize high performance 3D integrated microelectronic devices. Organic additives are used to deposit the copper defect free into the high aspect ratio vias. The decomposition of these organic additives can disturb the TSV filling process.
The impact of Accelerator decomposition products to the process stability of a model TSV filling processes was investigated. Copper (I) thiolate was found to be the main contributor to the process fluctuations. Already at very low concentrations the fill performance of a model TSV filling process is disturbed. (Fig. 1)
The chemistry of copper (I) thiolate formation and decomposition is discussed and a method for copper (I) thiolate determination in TSV electrolytes is introduced.
The increase of process stability by counteracting copper (I) thiolate is discussed and illustrated on hand of examples.

Figure 1
Towards Quantification of Contaminants in Electrodeposited Cu Films
Authors: Hai N. T. M. , Grimaudo Valentine , Moreno-García Pavel , Broekmann Peter 
Published: February 2020

A Cu electroplating process is typically used in semiconductor industry for the on-chip fabrication of interconnects on non-planar (patterned) wafer surfaces with feature dimensions ranging from the sub-10nm level (advanced Damascene applications) up to the micrometer level (Through Silicon Via technology). The presence of particular additives in the plating bath during the electroplating is a crucial prerequisite for the successful fill of vias and trenches with Cu. The accumulation of contaminants in the resulting Cu film is known to significantly decelerate the post-deposition recrystallization that is mandatory to improve the conductivity of these interconnects. It is therefore vital to develop new analytical techniques allowing a precise (true) quantification of the contamination level in the Cu deposit. Classical Secondary Ion Mass Spectrometry (SIMS) depth profiling approaches only provide semi-quantitative information on the contamination level with a poor depth resolution.
In this contribution we report on a recently developed quantitative depth profiling technique with sub-nanometer depth resolution based on laser ablation ionization mass spectrometry (LIMS). The high vertical depth resolution, a high dynamic range >108 coupled with a high detection sensitivity of ~ 10 ppb allows the identification/quantification of trace amounts of contaminants localized at grain boundaries of the Cu deposit. Results of the LIMS techniques are compared with complementary 3D atom probe tomography experiments.
To demonstrate the capabilities of these analytical techniques we use copper films electrodeposited in the presence of SPS (bis-(sodium-sulfopropyl)-disulfide) and Imep (polymerizates of imidazole and epichlorohydrin) additives as model system. This approach allows the targeted insertion of grain boundaries into the Cu film perpendicular to the growth (depth profiling) direction.
(invited) Copper Electroplating Technology for Packaging
Authors: Lai Chien-Hsun , Yuan Yu Cheng , Arnold Marco , Mayer Dieter 
Published: February 2020

Copper pillar is a transformative technology for next generation 2.5D/3D packaging. Fine-pitch copper pillar bumps have replaced conventional flip chip solder bumps when the need for extremely low profile, high connectivity interconnect is required. Cu pillar Flip-Chip is expected to grow at a 35% CAGR between 2010 - 2018 in terms of wafer count. It will be a key interconnect technology in future semiconductor packages. However, it is not just copper deposition into vias, but also needs high speed trough-mask wafer plating, high uniform bump height, flat bump shape, good surface morphology and electric reliability. Copper deposition in microvias is effected by electric field which is photoresist shielding causing “current distribution”. A bump center has higher current density than peripheries, so the shape will become convex. The inner microvia flow field is another factor which causes higher copper ion concentration at center and forms a domed bump. Although, these two factors will cause a convex bump shape, additives can influence the electroplating behaviors. Commercial additives can let bump shape become very flat, but it needs stable flow system and small dosage windows. CUPUR U is a unique package which can control bump shape by one additive concentration. It can selectively inhibit the bump center current distribution, let domed bump shape becomes flat, even dimple or dish shape. This property is not only controlling bump shape, but also improve the uniformity. They can be used in high flow system, high current density (> 20 ASD) and wide dosage windows in copper sulfate system. The package can be used on other BEOL application, such as micro-bump, RDL, UBM at high speed plating.
Combined Surface-Activated Bonding Technique for Low-Temperature Cu/SiO2 Hybrid Bonding
Authors: He Ran , Fujino Masahisa , Yamauchi Akira , Suga Tadatomo 
Published: February 2020

Low-temperature wafer bonding is one of key enabling technologies for manufacturing silicon-on-insulator (SOI), micro-electromechanical systems (MEMS), and the emerging three-dimensional (3D) integration. Among many other bonding approaches, low-temperature SiO2-SiO2 bonding and Cu-Cu bonding have been extensively studied because of their high bonding quality and CMOS compatibility. As an evolution of SiO2-SiO2 bonding and Cu-Cu bonding, Cu/SiO2 hybrid bonding provides both ultrafine metal interconnections and enhanced bonding stability during the single bonding process. However, this bonding approach remains difficult because of the challenging simultaneous surface activation of the hybrid surface. For instance, plasma treatment is effective for SiO2 surface activation, but it may induce formation of Cu2O/CuO and increase of surface roughness on Cu surface, which prevents successful hybrid bonding at low temperatures. Therefore, novel bonding techniques with compatibility with hybrid surface are highly desired for low-temperature Cu/SiO2h hybrid bonding.
This work develops a combined surface-activated bonding (SAB) technique for low-temperature Cu/SiO2 hybrid bonding at below 200 °C. The technique involves combinations of Ar beam bombardment, Si deposition, and water vapor exposure for prebonding surface activation prior to bonding in vacuum. Homogeneous (i.e., SiO2-SiO2 and Cu-Cu) and heterogeneous (i.e., Cu-SiO2) wafer bonding were carried out with the same bonding technique. Surface properties of the surface-activated wafers have been investigated using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). Bonding strength has been measured by crack-opening method and tensile test. Bonding interfaces have been inspected by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). Mechanisms of prebonding surface activation and bonding interface evolution during low-temperature postbonding annealing are discussed based on our results.
(Invited) Simulation Studies of Multilayer Electrode Coatings
Authors: Spotnitz Robert 
Published: February 2020

The use of extrusion coating for lithium-ion battery electrodes enables the practical possibility of using multilayer coatings to improve battery performance. The use of multilayer coatings of different materials, for example, a LiFePO4 coating next to a LiCoO2 coating, or a NMC coating next to a LiMn2O4 coating, has been experimentally tested in the literature [1-2] and modeling approaches [3-4] to optimize multilayer coatings presented. In this presentation simulation results the effect segregating particles into discrete layers are presented for both high power and high energy cells.
References

J.F. Whitacre, K. Zaghib, W.C. West, B.V. Ratnakumar “Dual active material composite cathode structures for Li-ion batteries”, J. Power Sources 177 (2008) 528–536.

W.B. Chu, D-J. Liu, C.C. Chen. L.-C. Chen, S.-T. Tseng, S.H. Wen, C.R. Yang, U. S. Patent Application US 2014/0162118 A1, Jun. 12, 2014 “Electrode Structure of Lithium Ion Battery”.

V. Ramadesigan, R.N. Methekar, F. Latinwo, R.D. Braatz, V.R. Subramanian, “Optimal Porosity Distribution for Minmized Ohmic Drop across a Porous Electrode”, J. Electrochem. Soc. 157 (12) A1328-A1334 (2010).

S. Golmon, K. Maute, M. Dunn, “A design optimization methodology for Li+ batteries” J. Power Sources 253 (2014) 239-250
Dielectric Properties of Ethylene Carbonate and Propylene Carbonate Using Molecular Dynamics Simulations
Authors: You Xinli , Chaudhari Mangesh , Rempe Susan , Pratt Lawrence R 
Published: February 2020

Ethylene carbonate (EC) and propylene carbonate (PC) are two widely used solvents in Li-ion batteries and supercapacitors. Ion diffusion in these solvents depends strongly on accurate predictions of solvent dielectric properties. We used all-atom molecular dynamics simulations of these pure solvents to calculate dielectric constants and dielectric relaxation times at various temperatures. The dielectric constant measures polarization of a material whereas dielectric relaxation measures the lag of the polarization in a dielectric medium in responding to a change in an applied field. Predicted values are compared with the available experimental results to validate the force field parameters (OPLS-AA) for these solvents. Current results for dielectric constant and dielectric relaxation time indicate that OPLS-AA force field produces reasonable agreement with experiment for both EC and PC.
Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U. S. Department of Energys National Nuclear Security Administration under contract DE-AC04-94AL85000