Reliability-Aware SPICE Compatible Compact Modeling of IGZO Inverters on a Flexible Substrate

Accurate circuit simulation reflecting physical and electrical stress is of importance in indium gallium zinc oxide (IGZO)-based flexible electronics. In particular, appropriate modeling of threshold voltage (VT) changes in different bias and bending conditions is required for reliability-aware simulation in both device and circuit levels. Here, we present SPICE compatible compact modeling of IGZO transistors and inverters having an atomic layer deposition (ALD) Al2O3 gate insulator on a polyethylene terephthalate (PET) substrate. Specifically, the modeling was performed to predict the behavior of the circuit using stretched exponential function (SEF) in a bending radius of 10 mm and operating voltages ranging between 4 and 8 V. The simulation results of the IGZO circuits matched well with the measured values in various operating conditions. It is expected that the proposed method can be applied to process improvement or circuit design by predicting the direct current (DC) and alternating current (AC) responses of flexible IGZO circuits.

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Fabrication of Atomic Layer Deposited Zinc Oxide Thin Film Transistors with Organic Gate Insulator on Flexible Substrate

Molecular Crystals and Liquid Crystals ◽

10.1080/15421406.2010.495889 ◽

2010 ◽

Vol 529 (1) ◽

pp. 131-136 ◽

Cited By ~ 4

Author(s):

Kyung Min Choi ◽

Gun Woo Hyung ◽

Jin Woo Yang ◽

Ja Ryong Koo ◽

Young Kwan Kim ◽

...

Keyword(s):

Thin Film ◽

Zinc Oxide ◽

Thin Film Transistors ◽

Flexible Substrate ◽

Atomic Layer ◽

Gate Insulator ◽

Oxide Thin Film ◽

Zinc Oxide Thin Film

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Coverage and Stability of NHx Terminated Cobalt and Ruthenium Surfaces: a First Principles Investigation

10.26434/chemrxiv.8428217 ◽

2019 ◽

Author(s):

Ji Liu ◽

Michael Nolan

Keyword(s):

Metal Surfaces ◽

High Vacuum ◽

Atomic Layer ◽

Nitrogen Plasma ◽

Operating Conditions ◽

Ultra High Vacuum ◽

Bridge Site ◽

Stable Surface ◽

Saturation Coverage ◽

The Stability

<div>In the atomic layer deposition (ALD) of Cobalt (Co) and Ruthenium (Ru) metal using nitrogen plasma, the structure and composition of the post N-plasma NHx terminated (x = 1 or 2) metal surfaces are not well known but are important in the subsequent metal containing pulse. In this paper, we use the low-index (001) and (100) surfaces of Co and Ru as models of the metal polycrystalline thin films. The (001) surface with a hexagonal surface structure is the most stable surface and the (100) surface with a zigzag structure is the least stable surface but has high reactivity. We investigate the stability of NH and NH2 terminations on these surfaces to determine the saturation coverage of NHx on Co and Ru. NH is most stable in the hollow hcp site on (001) surface and the bridge site on the (100) surface, while NH2 prefers the bridge site on both (001) and (100) surfaces. The differential energy is calculated to find the saturation coverage of NH and NH2. We also present results on mixed NH/NH2-terminations. The results are analyzed by thermodynamics using Gibbs free energies (ΔG) to reveal temperature effects on the stability of NH and NH2 terminations. Ultra-high vacuum (UHV) and standard ALD</div><div>operating conditions are considered. Under typical ALD operating conditions we find that the most stable NHx terminated metal surfaces are 1 ML NH on Ru (001) surface (350K-550K), 5/9 ML NH on Co (001) surface (400K-650K) and a mixture of NH and NH2 on both Ru (100) and Co (100) surfaces.</div>

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Optimized Al-doped TiO2 gate insulator for metal-oxide-semiconductor capacitor on Ge substrate

Journal of Materials Chemistry C ◽

10.1039/d0tc04725b ◽

2021 ◽

Author(s):

Dong Gun Kim ◽

Cheol Hyun An ◽

Sanghyeon Kim ◽

Dae Seon Kwon ◽

Junil Lim ◽

...

Keyword(s):

Metal Oxide ◽

Leakage Current ◽

Tio2 Film ◽

Single Layer ◽

Atomic Layer ◽

Metal Oxide Semiconductor ◽

Gate Insulator ◽

Oxide Semiconductor ◽

High K ◽

Metal Oxide Semiconductor Capacitor

Atomic layer deposited TiO2- and Al2O3-based high-k gate insulator (GI) were examined for the Ge-based metal-oxide-semiconductor capacitor application. The single-layer TiO2 film showed a too high leakage current to be...

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Design of Molecular Water Oxidation Catalysts Stabilized by Ultrathin Inorganic Overlayers—Is Active Site Protection Necessary?

Inorganics ◽

10.3390/inorganics6040105 ◽

2018 ◽

Vol 6 (4) ◽

pp. 105 ◽

Cited By ~ 5

Author(s):

Laurent Sévery ◽

Sebastian Siol ◽

S. Tilley

Keyword(s):

Water Oxidation ◽

Atomic Layer ◽

Deposition Process ◽

Operating Conditions ◽

Molecular Water ◽

Side Reactions ◽

Aqueous Environment ◽

Oxidation Catalysts ◽

Initial Onset ◽

Anchoring Groups

Anchored molecular catalysts provide a good step towards bridging the gap between homogeneous and heterogeneous catalysis. However, applications in an aqueous environment pose a serious challenge to anchoring groups in terms of stability. Ultrathin overlayers embedding these catalysts on the surface using atomic layer deposition (ALD) are an elegant solution to tackle the anchoring group instability. The propensity of ALD precursors to react with water leads to the question whether molecules containing aqua ligands, such as most water oxidation complexes, can be protected without side reactions and deactivation during the deposition process. We synthesized two iridium and two ruthenium-based water oxidation catalysts, which contained an aqua ligand (Ir–OH2 and Ru–OH2) or a chloride (Ir–Cl and Ru–Cl) that served as a protecting group for the former. Using a ligand exchange reaction on the anchored and partially embedded Ru–Cl, the optimal overlayer thickness was determined to be 1.6 nm. An electrochemical test of the protected catalysts on meso-ITO showed different behaviors for the Ru and the Ir catalysts. The former showed no onset difference between protected and non-protected versions, but limited stability. Ir–Cl displayed excellent stability, whilst the unprotected catalyst Ir–OH2 showed a later initial onset. Self-regeneration of the catalytic activity of Ir–OH2 under operating conditions was observed. We propose chloride ligands as generally applicable protecting groups for catalysts that are to be stabilized on surfaces using ALD.

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Effect of Annealing and Gate Insulator Material Changing on the Performances of IGZO-TFT

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.670-671.1467 ◽

2014 ◽

Vol 670-671 ◽

pp. 1467-1470

Author(s):

Ji Feng Shi ◽

Long Long Chen ◽

Xiang Sun

Keyword(s):

High Temperature ◽

Active Layer ◽

Room Temperature ◽

Rf Magnetron Sputtering ◽

Gate Insulator ◽

Oxide Thin Film ◽

Indium Gallium Zinc Oxide ◽

Zinc Oxide Thin Film ◽

Suitable Temperature ◽

Igzo Tft

Indium-gallium-zinc oxide Thin Film Transistors (IGZO-TFT) were separately prepared with SiOx and SiNx/ SiOx as gate insulator,with IGZO films deposited at room-temperature by RF magnetron sputtering method as active layer.Compared with TFT with SiOx as gate insulator, The saturation mobility and the on/off ratio of TFT with SiNx/ SiOx as gate insulator were much higher. And,the threshold swing was also smaller.But,the threshold voltage was not good enough,was larger. By annealing at 200°C in the air,the saturation mobility increased from 1.42 to 7.5 cm2.V-1.S-1. While, the saturation mobility had no obvious change when TFT was annealed at high temperature. Seriously, IGZO annealed at high temperature would become crystal,it was not good for the ohmic contact between active layer and metal conductive layer,and,the interface between active layer and insulator would be deteriorated.These will result in the threshold swing become larger and the on/off ratio get smaller.200°C is a suitable temperature for annealing. So,using SiNx/ SiOx films as gate insulator,together with TFT annealing at low temperature, could improve the performances of TFT effectively.

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Organic/Inorganic Hybrid-Type Nonvolatile Memory Thin-Film Transistor on Plastic Substrate below 150°C

MRS Proceedings ◽

10.1557/opl.2011.1147 ◽

2011 ◽

Vol 1287 ◽

Cited By ~ 2

Author(s):

Sung-Min Yoon ◽

Shinhyuk Yang ◽

Soon-Won Jung ◽

Sang-Hee Ko Park ◽

Chun-Won Byun ◽

...

Keyword(s):

Flexible Electronics ◽

Nonvolatile Memory ◽

Vinylidene Fluoride ◽

Thin Film Transistor ◽

Memory Device ◽

Gate Insulator ◽

Oxide Semiconductor ◽

Plastic Substrate ◽

Inorganic Hybrid ◽

Hybrid Type

ABSTRACTAn organic/inorganic hybrid-type nonvolatile memory TFT was proposed as a core device for the future flexible electronics. The structural feature of this memory TFT was that a ferroelectric copolymer and an oxide semiconductor layers were employed as a gate insulator and an active channel, respectively. The memory TFT with the structure of Au/poly(vinylidene fluoride-trifluoroethylene)/Al2O3/ZnO/Ti/Au/Ti/poly(ethylene naphthalate) could be successfully fabricated at the process temperature of below 150°C. It was confirmed that the TFT well operated as a memory device even under the bending situations.

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Research Progress in the Preparation of Flexible Substrate Barrier Films

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1027.91 ◽

2021 ◽

Vol 1027 ◽

pp. 91-98

Author(s):

Li Xia Guan ◽

Zhao Yi Zhou ◽

Yi Jing Huang

Keyword(s):

Thin Film ◽

Thin Films ◽

Flexible Electronics ◽

Flexible Substrate ◽

Research Progress ◽

Barrier Films ◽

Main Challenge ◽

Long Life

The development of flexible electronics towards for the direction of bend ability, lightweight, portability, long life against falling. The performance of the substrate in the flexible electronics plays a very important role in the development of electronics. In this article, three preparation technologies of thin films are introduced, including CVD, PVD and ALD. The paper also introduces the research progress on the preparation of substrate barrier films, and one main challenge that may face by the preparation of thin film materials. In order to satisfy the development of flexible electronics, improving the substrate’s performance constantly is needed. Finally, the development of preparing barrier films is prospected.

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Screen Printing Fine Pitch Stretchable Silver Inks onto a Flexible Substrate for Wearable Applications

International Symposium on Microelectronics ◽

10.4071/2380-4505-2018.1.000665 ◽

2018 ◽

Vol 2018 (1) ◽

pp. 000665-000671

Author(s):

Jianbiao Pan ◽

Malcolm Keif ◽

Joshua Ledgerwood ◽

Xiaoying Rong ◽

Xuan Wang

Keyword(s):

Sheet Resistance ◽

Flexible Electronics ◽

Screen Printing ◽

Flexible Substrate ◽

Thermoplastic Polyurethane ◽

Organic Substrate ◽

Printing Process ◽

Silver Ink ◽

Fine Pitch

Abstract The lightweight and bendable features of printed flexible electronics are increasingly attractive. Currently stretchable silver inks are formulated for wide traces, typically larger than 2 mm. To attach ultra-thin silicon chips that have fine pitch onto printed organic substrate, it is necessary to print fine trace width/space that matches the pitch of the chips, which may be less than 200 microns. This paper presents the development and optimization of the screen printing process for printing stretchable silver ink onto stretchable thermoplastic polyurethane (TPU) substrate. A test vehicle was designed including 50 μm/5 mm (line width/line length) to 350 μm/35 mm lines (at 4 biases). The stretchable ink selected was DuPont PE 873 and Dupont's PE 5025 ink (non-stretchable conductive flake silver) was used as a “control” to baseline the printing process. The substrate used was Bemis TPU ST604. The experiment was done on a DEK Horizon 03i printer. A DEK squeegee 200 (Blue) and a DEK 265 flood bar (200 mm) were used. A 2-level factorial design with three replicates was selected to investigate the effect of process parameters on the quality of prints. The quality of the prints is characterized by 1) resistance of traces, 2) sheet resistance, 3) z-axis height, and 4) trace width/spacing. We observed significant noise in the z-axis printed silver ink height measured by profilometry and concluded z-axis height is not a good response variable for characterizing screen printing stretchable silver ink onto TPU substrate, mainly due to high roughness of the TPU substrate. We proposed calculated sheet resistance based on the measured resistance value, trace width, and trace length, which can replace trace height measurements on rough profile substrates. We found that squeegee pressure and emulsion thickness have statistically significant effects on calculated sheet resistance of print traces while print speed does not have statistically significant effects. In our experiment setting levels, the lower the squeegee pressure, the lower the calculated sheet resistance that is achieved. The emulsion with higher emulsion over mesh (EOM) is better than the emulsion with lower EOM since it can achieve lower sheet resistance. After optimizing the screen printing process, we were able to print 100 μm (4 mils) trace width and spacing with high consistency.

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Flexibility of Fluorinated Graphene-Based Materials

Materials ◽

10.3390/ma13051032 ◽

2020 ◽

Vol 13 (5) ◽

pp. 1032 ◽

Cited By ~ 1

Author(s):

Irina Antonova ◽

Nadezhda Nebogatikova ◽

Nabila Zerrouki ◽

Irina Kurkina ◽

Artem Ivanov

Keyword(s):

Chemical Vapor Deposition ◽

Polyvinyl Alcohol ◽

Vapor Deposition ◽

Tensile Strain ◽

Flexible Substrate ◽

Chemical Vapor ◽

Multilayer Graphene ◽

Current Ratio ◽

Bending Radius ◽

Fluorinated Graphene

The resistivity of different films and structures containing fluorinated graphene (FG) flakes and chemical vapor deposition (CVD)-grown graphene of various fluorination degrees under tensile and compressive strains due to bending deformations was studied. Graphene and multilayer graphene films grown by means of the chemical vapor deposition (CVD) method were transferred onto the flexible substrate by laminating and were subjected to fluorination. They demonstrated a weak fluorination degree (F/C lower 20%). Compressive strains led to a strong (one-two orders of magnitude) decrease in the resistivity in both cases, which was most likely connected with the formation of additional conductive paths through fluorinated graphene. Tensile strain up to 3% caused by the bending of both types of CVD-grown FG led to a constant value of the resistivity or to an irreversible increase in the resistivity under repeated strain cycles. FG films created from the suspension of the fluorinated graphene with a fluorination degree of 20–25%, after the exclusion of design details of the used structures, demonstrated a stable resistivity at least up to 2–3% of tensile and compressive strain. The scale of resistance changes ΔR/R0 was found to be in the range of 14–28% with a different sign at the 10% tensile strain (bending radius 1 mm). In the case of the structures with the FG thin film printed on polyvinyl alcohol, a stable bipolar resistive switching was observed up to 6.5% of the tensile strain (bending radius was 2 mm). A further increase in strain (6.5–8%) leads to a decrease in ON/OFF current ratio from 5 down to 2 orders of magnitude. The current ratio decrease is connected with an increase under the tensile strain in distances between conductive agents (graphene islands and traps at the interface with polyvinyl alcohol) and thickness of fluorinated barriers within the active layer. The excellent performance of the crossbar memristor structures under tensile strain shows that the FG films and structures created from suspension are especially promising for flexible electronics.

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