bluuebunny/crossref_metadata_2025_split huggingface dataset:
Breakdown Characteristics of TiN/HfxZr1-xO2/Al2O3/Ge Gate Stacks
Authors: Shao Pai , Bhuyian Md Nasir Uddin , Ding Yiming , Misra Durgamadhab 
Published: February 2020

Ge has been considered as an alternative channel material in place of Si because of its higher electron and hole mobility. Since direct deposition of high-k material on Ge leads to degradation of interface quality ultrathin Al2O3 is used as a passivation layer prior to high-k layer deposition. In addition, ZrO2/Al2O3 bilayer as gate dielectric on Ge is becoming popular since ZrO2 showed lower leakage current than HfO2 (1, 2). To further scale the effective oxide thickness (EOT) on Ge higher-k dielectric materials like Hf1-xZrxO2, with different Hf to Zr compositions has been explored. Furthermore, the recent introduction of post-deposition slot plane antenna plasma oxidation (SPAO) of the dielectric seems to enhance the interface as well as gate stack quality (3).
In this work, we investigate the Time Dependent Dielectric Breakdown (TDDB) characteristics of the impact of TiN/HfxZr1-xO2/Al2O3/Ge gate stacks by changing the Zr content. Slot-plane antenna plasma oxidation (SPAO) was performed on these devices after the ALD deposition of the high-k layers. It was observed that the equivalent oxide thickness (EOT) decreases with Zr addition in HfO2 with up to 75% of Zr incorporation. With 100% Zr incorporation EOT increased significantly. This is possibly due to the formation of low-k interfacial GeO2 at the interface for 100% Zr whereas for other samples have comparatively thinner GeOx interfacial layers (3). Weibull plots shows that charge to breakdown (Q
BD) increased with increase the Zr percentage. However, the breakdown acceleration factor decreased with Zr percentage up to 75% and increased rapidly for 100% Zr content. It is reported earlier (3) that GeO2 has the worst resistance to stress in terms of device stability compared to GeOx. Therefore, formation of thick GeO2 degrades the device with 100% Zr rapidly as compared to lower percentage of Zr.
The authors would like to acknowledge K. Tapily, R. D. Clark, S. Consiglio, C. S. Wajda, and G. J. Leusink of TEL Technology Center, Albany, NY for their help in device preparation.

References:

X.-F. Li et al, ECS Solid State Letters 1 (2), N10-N12 (2012).

M. N Bhuyian et al, ECS Journal of Solid State Science and Technology 3 (5), N83-N88 (2014).

Y. Ming et al, IEEE Transactions on Device and Materials Reliability, DOI: 10.1109/TDMR.2017.2681428
Manipulation on Crystallization of Perovskite Thin-films during Blade Coating Fabrication in Air
Authors: Li Jing , Lin Yichuan , Yin Jun , Zheng Nanfeng 
Published: February 2020

Organometal trihalide perovskite solar cells (PSCs) have drawn more and attention in the past few years due to the merits of low-cost preparation processes and rapidly improved power conversion efficiency (PCE) with latest certified efficiency of 22.1%.1-4 Commonly, solution processes, including one- or two-step spin-coating methods, are often employed to produce perovskite films.5, 6 Recently, the blade coating technique, with the advantages of large scale fabrication and mass production besides the well-accepted low-cost manner, has also attracted researchers’ interest for the rapid growth of perovskite films.7-8 However, nucleation and crystal growth during the film’s crystallization by blade coating are still lack of controlling, generally resulting in relatively poorer crystal quality and film uniformity. So, further strategies are required to improve the crystallization of perovskite films and ultimate device efficiencies.
In this work, different strategies were introduced during the blade-coating process to control and manipulate the crystallization of perovskite films. In depth understanding in the nucleation mechanisms and growth dynamics of films were well accomplished. As a result, the rapid growth of perovskite films with high quality and good optical performances were successfully produced. Correspondingly, efficient PSCs were correspondingly fabricated.

References

1. A. Kojima, K. Teshima, Y. Shirai and T. Miyasaka, J. Am. Chem. Soc., 2009, 131, 6050-6051.
2. M. D. McGehee, Nature Mater., 2014, 13, 845-846.
3. J. Seo, J. H. Noh and S. I. Seok, Accounts of chemical research, 2016, 49, 562-572.
4. http://www.nrel.gov/ncpv/images/efficiency_chart.jpg
5. H. S. Jung and N. G. Park, Small, 2015, 11, 10-25.
6. J.-H. Im, H.-S. Kim and N.-G. Park, APL Materials, 2014, 2, 081510.
7. J. H. Kim, S. T. Williams, N. Cho, C.-C. Chueh and A. K. Y. Jen, Adv. Energy Mater., 2015, 5, 1401229.
8. Y. Deng, E. Peng, Y. Shao, Z. Xiao, Q. Dong and J. Huang, Energy Environ. Sci., 2015, 8,1544-1550.
Intense Pulsed Light Processing of Perovskite Thin Films
Authors: Druffel Thad 
Published: February 2020

The manufacturing of solar photovoltaic panels has seen dramatic reductions in costs primarily through business innovations to the extent that the industry is quite large. The industry is dominated by a single technology, crystalline solar cells. The implementation of newer technologies that could further reduce costs are very attractive, especially technologies that can be adapted to continuous printing particularly involving polymer film substrate. The perovskite solar cells offers this; however, most of the processing techniques rely on extended thermal process or very exact solvent control. The Intense Pulsed Light (IPL) technology has been shown to rapidly process perovskite thin films and our recent work explores how the technology can open up the processing window.
The Intense Pulsed Light technology is well suited to continuous manufacturing platforms such as roll-to-roll due to its very large processing area and rapid processing time scales. The IPL technique delivers high energy pulses of broad spectrum light (UV-Vis-NIR) in a very short duration (ms) over a large processing area (100 cm2). In the past few years, the method has found a number of applications within the flexible electronics industry as printed structures for wire traces, transparent conductors and RFID and is now gaining traction with more complex materials. The most promising opportunity for the IPL within photovoltaics is the application towards the flexible large area roll-to-roll production offered by the solution phase processed perovskites.
In this paper we will discuss our work with the IPL and the extremely rapid processing of perovskite thin films using a number of precursor materials. We have shown the process for both the two-step and the single step deposition producing devices that perform as well as the traditional thermal processing at significantly faster speeds. This paper will also discuss the morphological changes that occur during the IPL with an intent to develop a robust process. Data from X-ray diffraction and scanning electron microscopy is used to describe the changes to the films, and current-voltage and electrochemical impedance spectroscopy is used to probe the devices.
(Invited) 2D-Functionality in Full 3D: A New Paradigm of Graphene-Metal Epitaxial Systems
Authors: Alamgir Faisal M 
Published: February 2020

An unprecedented dual role for graphene in electrochemical systems will be shown in this presentation. First, graphene (GR) plays the role of an enabler, allowing a large-area, fully-wetted, growth of two-dimensional Pt films that are one to several monolayers thick. Next, it also serves the role of a ‘chemically transparent’ barrier that allows catalytic chemistry to take place above it, while protecting the catalyst below it from cyclical loss. In the latter case, we will specifically show that graphene does not restrict access of the reactants for the canonical oxygen reduction reaction (ORR) but does block Pt from dissolution or agglomeration. Using these architectures, we show that it is possible to simultaneously achieve enhanced catalytic activity and unprecedented stability,e.g. retaining full activity for ORR beyond 1000 cycles . Using x-ray photoemission/absorption spectroscopy (XPS/XAS), high resolution TEM, AFM, Raman, and electrochemical methods, we show that, due to intimate graphene-Pt epitaxial contact, Pt/GR hybrid architectures are able to induce a compressive strain on the supported Pt adlayer and increase catalytic activity for ORR. We further investigate graphene as a sandwiched layer between metal films as a membrane that limits interfussion and, therefore, helps retain the integrity of core-shell architectures. We find that at operating temperatures above 100 °C (not uncommon in low-temperature fuel cells), there is appreciable interdiffusion between the primary and support metals of the catalyst system, which can diminish the catalyst activity. A single-layer of graphene acts as a barrier that prevents unwanted surface alloying between layered metals, while allowing interlayer charge transfer. Our demonstration of a the room-temperature, wetted synthesis approach, should allow for efficient transfer of charge, strain, and phonons and photons, impacting not just catalysts, but also electronic, thermoelectric and optical materials.
Metal Underpotential Deposition to Quantify Defects in 2D Materials
Authors: Dorner Iris , Müllner Matthias , Mertens Stijn F. L. 
Published: February 2020

We demonstrate how metal UPD may find use as a general tool to determine the collective defect area in hybrids between 2D materials (graphene, hexagonal boron nitride, etc.) and various substrate metals. By investigating copper UPD on a monolayer of hexagonal boron nitride (h-BN) on Rh(111), we explore how this process can be used to quantify the defects in the h-BN monolayer which form during its chemical vapor deposition. In addition, the UPD signature allows assessing the potential window of the h-BN/metal hybrid, which is important to explore its functionality under ambient and electrochemical conditions. Importantly, UPD itself does not alter the defect area on repeated cycling. Overpotential deposition, on the other hand, is shown to have significant consequences on the defect area. We show that this non-innocent Cu electrodeposition involves intercalation originating at initial defects, causing irreversible delamination of the h-BN layer; this effect therefore may be used for 2D material nanoengineering.
In-Situ Measurements of Stress during Electrodeposition of Copper Nanofilms: Effects of Deposition Rate and Grain Size
Authors: Buckley D. Noel , Murphy Joe A. , Lenihan Catherine , Chason Eric , Lynch Robert P. 
Published: February 2020

Thin metal films deposited on a substrate are usually in a state of stress and this has been the subject of extensive experimental investigation and theoretical analysis. [1-4] Various studies of the stress generated during the electrodeposition and aging of copper films have been reported.
In this paper we report results of in situ stress monitoring during deposition of copper nanofilms from acidic CuSO4 electrolytes. Stress was monitored over a larger range of growth rates from 0.22 nm s-1 to 6.9 nm s-1 during deposition from additive-free electrolyte. At low growth rates, steady state stress was compressive. As growth rate was increased, the stress became less compressive and eventually became tensile. Crossover from compressive to tensile stress occurred at a growth rate of ~1 nm s-1. Both in-situ AFM imaging during deposition and ex-situ SEM imaging were used to characterise the evolution of grain size. In general, grain size increased with continued deposition but eventually reached a constant value.
Simulations based on a kinetic model [3] gave an excellent fit of our experimental stress measurements in the region of constant grain size (~870 nm). In the region of variable grain size, a fit of the model to the experimental data gave a grain size that is in good agreement with the average (520 nm) obtained from SEM and AFM.
The observed behaviour supports Chason’s model [3] of stress development in thin films. According to that model, stress originates primarily from effects at grain boundaries. As grain boundaries form, tensile stress tends to develop because of a so-called “zipping” effect whereby the surfaces of adjacent grains near the film surface tend to attract once the separating distance becomes small. When the attraction between adjacent grains becomes strong enough, they “zip” together, closing the gap between them and creating tensile stress as the material stretches slightly to fill the gap. Similar effects occur near the film surface as existing grains continue to grow: when the atoms at the edges of terraces on two adjacent grains get sufficiently close to each other they bond to each other even if that bond causes stress in the layer. This tensile stress can be relaxed or made compressive by the insertion of atoms into the grain boundary by diffusion from the surface. Our experimental results will be discussed in detail in terms of this model.

References

O.E. Kongstein, U. Bertoci, G.R. Stafford, J. Electrochem. Soc.
152, C116 (2005)

S. Ahmed, T.T. Ahmed, M. O'Grady, S. Nakahara, D.N. Buckley, J. Applied Physics
103, 073506 (2008)

E. Chason, Thin Solid Films
526, 1 (2012)

E. Chason, A. Engwall, F. Pei, M. Lafouresse, U. Bertocci, G. Stafford, J.A. Murphy, C. Lenihan, D.N. Buckley,J. Electrochem. Soc.
160, D3285 (2013)

Figure 1
Two-Dimensional Semiconductors Thin Films of MoS2 and MoSe2 on Ag(111)
Authors: Salvietti Emanuele , Vizza Martina , Giaccherini Andrea , Passaponti Maurizio , Piciollo Emanuele , Di Benedetto Francesco , Cavallini Massimiliano , Innocenti Massimo 
Published: February 2020

In the recent years, technological development in the fields spanning from nanoelectronics to new solar energy materials, requires highly controlled nanostructured surfaces, ultra-thin films and 2D structured materials.
The Electrochemical Atomic Layer Deposition (E-ALD) is one of these techniques that allows us to produce thin films of semiconductor. Exploiting Surface Limited Reactions (SLR), it enables the deposition of highly ordered ultra-thin films from diluted aqueous solutions and at room temperature and pressure.
Underpotential deposition (UPD) is a type of electrochemical SLR, where an atomic layer of a first element is deposited on a second, at a potential prior to (under) that needed to deposit the first element on itself, so that the resulting deposit is generally limited to an atomic layer.
It occurs when the depositing element is able to somehow interact with the substrate, so that the deposition of the layer in direct contact with the substrate occurs at a potential preceding bulk deposition, that is, the deposition of the element on itself.
MoS2 and MoSe2 are important transition metal dichalcogenides (TMDs). E-ALD method was used to obtain semiconductor compounds in the form of thin films. UPD anodic electrodeposition of Na2S and Na2SeO3 on crystalline Ag[111] electrode are well-known. The research move to discover the optimal conditions to deposit Mo on Ag/S and on Ag/Se from a solution of MoO4
2- in alkaline buffer. This study has been carried by means of voltammetric techniques, XPS and AFM characterizations of the deposit.
In-Situ observation of Cu Electrodeposition and Dissolution Behavior By Video-AFM
Authors: Yoshioka Taiki , Matsushima Hisayoshi , Ueda Mikito 
Published: February 2020

1. Introduction
Advanced nanotechnology applications are requires copper plating and epitaxial control by electrochemical method, which is used for various electronic devices such as a micro machine technology (MEMS). To control the surface structure of the plating film with high precision at the nanometer size, it is indispensable to clarify the mechanism of electrodeposition. However, since the electrochemical reaction process in nucleation and growth occurs rapidly in a small area, it is extremely difficult to capture the dynamic behavior at the nanoscale. In this study, we investigate the nucleation and growth process at the initial stage of copper electrodeposition by using Video-AFM.
2. Experimental
A three-electrode electrochemical AFM cell was used for in-situ observation. In the cell, the working electrode was single crystal Au(100) substrate (φ= 3 mm). The reference electrode was a copper wire and the counter electrode was a platinum wire. Potentiostatic electrodeposition was carried out in an aqueous electrolyte containing 3 mM CuSO4 and 50 mM H2SO4 at room temperature. The Video-AFM measurement was performed during potentiostatic electrodeposition. The image area (500×375 nm2) was recorded at 2 flame s-
1

3. Results and discussion
When the experiment was carried out at -0.09 V, the initial stage of the deposition on Au substrate was shown in Fig.1(a)~(d). Before electrodeposition, a smooth substrate without any irregularities was observed. Immediately after the start of electrodeposition, copper deposited with about 100 nm in x-axis direction instantaneously (Fig.1 (a)), and it was confirmed that growth of the deposited copper in the planar direction (Fig.1 (b) ~ (d)). From these images, the local deposition rate in the planar direction was calculated as 45 nm s-
1. From the height profile, the thickness of the deposit was about 1 nm, which was corresponding to 4 or 5 atomic layers.

Figure 1
Au-Pd-Pt Multilayer Catalyst for Miniature Fuel Cells
Authors: Shirai Ryo , Vasiljevic Natasa , Hayase Masanori 
Published: February 2020

We have developed miniature fuel cells with monolithically fabricated Si electrodes. In the fuel cells, two Si electrodes with porous Pt catalyst layer, which Pt usage was 3.6mg/cm2, were hot-pressed onto either side of a PEM (polymer electrolyte membrane), and the prototype fuel cells showed promising performances of over 500mW/cm2 output at 313K with H2-O2. However, recent improvements of Li-ion battery are lowering expectation to the miniature fuel cells. The advantage of the fuel cell, i.e. clean and efficient energy source, should be strengthened.
Bio-mass is an ultimate energy source. Hydrogen can be produced by gasification of the bio-mass in reducing environment, but high CO concentration in the bio-mass derived hydrogen is inevitable. Catalyst poisoning by CO is problematic. We found that our Pd-Pt catalyst obtained by using UPD-SLRR had promising feature. Though the catalyst layer used only 6μg/cm2 of Pt, high tolerance to CO was observed. But Pd and Pt are rare metals, and both amounts should be minimized. In this study, a novel Au-Pd-Pt multilayer catalyst is proposed. Though Au is also a precious metal, reserve of Au is much larger than Pd and Pt, and porous Au can be formed on a Si substrate by similar process to porous Pt.
There is no clear evidence, but it is assumed that high CO tolerance of the Pd-Pt catalyst is realized with sub-monolayer Pt on Pd. Hydrogen absorption or stress near the interface between Pd and Pt are sensitive to the number of atomic layer of Pd, and fine control of Pd and Pt deposition on Au is crucial. In our previous study, sub-monolayer Pt was deposited with Cu-UPD, but hydrogen also absorbs on some metal surfaces and form atomic monolayer at slightly under the equilibrium potential. The H-UPD-SLRR can be performed just in an acidic plating bath containing Pd2+ or Pt4+. There is no need to replace the plating bath, and repetition of the atomic layer deposition process will be easy. In this study, basic fabrication strategy of the Au-Pd-Pt multilayer catalyst using H-UPD-SLRR process was examined using Au wire. Preliminary results of cyclic voltammetry suggested that Pd and Pt were successfully deposited on Au wire, and only one Pt deposition cycle on the Au wire with Pd, deposited by several UPD-SLRR cycles, showed large hysteresis loop in the CV, which related to catalytic performance.
(Electrodeposition Division Research Award Address) Metal Deposition Assisted by UPD Monolayers-Fundamentals and Applications
Authors: Brankovic Stanko R 
Published: February 2020

The improved understanding of nucleation and growth kinetics provided the base for design of new experimental approaches where the thin film growth was manipulated to enhance the evolution of atomically flat epitaxial overlayers. Following this progress, a new protocols for electrochemical thin film growth were developed which benefit from the Underpotentially Deposited Monolayers (UPD ML) serving as a surfactants (Surfactant Mediated Growth, SMG), mediators (Defect Mediated Growth, DMG) or sacrificial materials (Deposition via Surface Limited Redox Replacement, SLRR) in electrodeposition process of thin films. In these examples, the essential step that results in desired 2D growth mode is achieved by precise control of the electrode potential, electrodeposition sequence and/or solution chemistry which enable particular action/benefit of the UPD ML to be fully exploited in the growth process.
In the first part of the talk we will briefly review fundamentals of the electrochemical thin film growth assisted by UPD ML. Our results and discussion are focused on examining the extendibility of SMG, DMG and SLRR approach for thin film growth in technologically relevant system such as Cu/Ru(hklm). The Cu/Ru(hklm) represents the overlayer/substrate system which has significant epitaxial strain (-5.5%). This fact together with room temperature growth conditions favor a 3D growth. However, as it will be shown, with convenient use of UPD ML serving as surfactant, or mediator, or sacrificial material a 2D growth of Cu on Ru can be achieved readily.
In the second part of the talk we will demonstrate that UPD-like ML can be deposited on different substrates using an electroless (e-less) approach. The example of improved morphology and magnetic properties of e-lessly deposited Co overlayers on Cu assisted by e-lessly deposited Pb ML serving as surfactant are analyzed. The phenomenon of e-less UPD-like ML deposition as a prelude for e-less atomic layer epitaxial deposition (E-less ALD) will be discussed as well. We will show results demonstrating noble metal thin film growth on Cu and other substrates using e-lessly deposited Pb UPD-like ML serving as a reducing precursor in SLRR reaction with noble metal ions such as Pt, Pd, and Ru. In conclusion of the talk, (if time permitted), the results from exploratory research studying the benefit of UPD ML serving as a stress moderators in electrodeposition process of Pd thin films will be discussed.
The author acknowledges support from Lam Research Corporation and NSF Chemistry division under the contract # 0955922 and #1605331.