Showing papers in "ECS Journal of Solid State Science and Technology in 2017"

Review—Organic Materials for Thermoelectric Energy Generation

Abstract: L.M.C and B.C.S. acknowledge the Materials Research Institute and Queen Mary University of London for financial support. M.J.C. would like to thank the EPSRC funded (EP/N506553/1) College of Engineering Doctoral Training Partnership at Swansea University.

Review—Silicon Nitride and Silicon Nitride-Rich Thin Film Technologies: Trends in Deposition Techniques and Related Applications

Abstract: This article provides an overview of the state-of-the-art chemistry and processing technologies for silicon nitride and silicon nitride-rich films, ie, silicon nitride with C inclusion, both in hydrogenated (SiNx:H and SiNx:H(C)) and non-hydrogenated (SiNx and SiNx(C)) forms The emphasis is on emerging trends and innovations in these SiNx material system technologies, with focus on Si and N source chemistries and thin film growth processes, including their primary effects on resulting film properties It also illustrates that SiNx and its SiNx(C) derivative are the focus of an ever-growing research and manufacturing interest and that their potential usages are expanding into new technological areas

Electrical Characteristics of Vertical Ni/β-Ga2O3 Schottky Barrier Diodes at High Temperatures

Abstract: Vertical geometry β-Ga2O3 Schottky barrier diodes (SBDs) were fabricated and the rectifying forward and reverse current-voltage characteristics were demonstrated at elevated temperatures for a freestanding β-Ga2O3 material with an ultra-wide bandgap of ~4.9 eV. The breakdown voltage of the fabricated β-Ga2O3 SBDs with a punch-through configuration was ~210 V without the edge-termination method. The electrical field and potential distributions were numerically simulated with a finite element method. The on-resistance was 2582 Ωcm2 at 25°C, and decreased to 0.043 Ωcm2 at 225°C. The figure-of-merit (VBR2/Ron) was approximately 17.1 Wcm−2. The temperature-dependent Schottky barrier height and ideality factor were also determined. The developed β-Ga2O3 SBDs with the punch-through structure exhibit great potential for high power and high temperature applications.

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-k Dielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

Abstract: Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-k Dielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride John T. Gaskins,a Patrick E. Hopkins,a,b,c,z Devin R. Merrill,d,e Sage R. Bauers,d Erik Hadland,d David C. Johnson,d,z Donghyi Koh,e,f Jung Hwan Yum,f Sanjay Banerjee,f,∗ Bradley J. Nordell,g Michelle M. Paquette,g Anthony N. Caruso,g William A. Lanford,h Patrick Henry,e Liza Ross,e Han Li,e Liyi Li,e Marc French,e Antonio M. Rudolph,e and Sean W. Kinge,∗,z

Temperature-Dependent Characteristics of Ni/Au and Pt/Au Schottky Diodes on β-Ga2O3

Abstract: Schottky diodes were formed on bulk or epitaxial β-Ga2O3 using Ni/Au or Pt/Au and the electrical characteristics measured as a function of temperature in the range 25–200°C. The barrier heights were 1.07 eV (Ni/Au) and 1.04 eV (Pt/Au) at 25°C. The barrier heights increased with temperature, while the on-state resistances (RON) decreased over the same range. The temperature coefficient of reverse breakdown voltage (VB), β, was −4 mV/K for Ni/Au and −0.1 mV/K for Pt/Au. The figure-of-merit (VB2/RON) was above 3 MW.cm−2 at 25°C for Ni/Au diodes and was still ~1 MW.cm−2 at 200°C. The reverse recovery times were also measured as a function of temperature and were of the order of 21–28 ns over the range 25–150°C for both epi and bulk diodes. The results show the already high quality of bulk and epitaxial β-Ga2O3 and the potential of this material for high temperature power electronics.

Review—The Current and Emerging Applications of the III-Nitrides

Abstract: III-Nitrides are attracting considerable attention as promising materials for a wide variety of applications due to their wide coverage of direct bandgap range, high electron mobility, high thermal stability and many other exceptional properties. The light-emitting diodes based on III-Nitrides revolutionize the solid-state lighting industry. III-Nitrides based solar cells and thermoelectric generators support the sustainable energy progress, and the III-Nitrides are better alternatives for power and radio frequency (RF) electronics compared with silicon. The doped III-Nitrides’ magnetic properties and sensitivity to radiation can contribute to novel spintronic and nuclear detection devices. This paper will review III-nitride material properties and their corresponding applications in LEDs, solar cells, power and radio frequency (RF) electronics, magnetic devices, thermoelectrics and nuclear detection. The typical values of electrical, optical, thermoelectric, magnetic properties are cited, the current state of art investigations are reported, and the future applications are estimated. © The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0101712jss] All rights reserved.

Review—Micro and Nano-Engineering Enabled New Generation of Thermoelectric Generator Devices and Applications

Abstract: As we are advancing our world to smart living, a critical challenge is increasingly pressing increased energy demand. While we need mega power supplies for running data centers and other emerging applications, we also need instant small-scale power supply for trillions of electronics that we are using and will use in the age of Internet of Things (IoT) and Internet of Everything (IoE). Such power supplies must meet some parallel demands: sufficient energy supply in reliable, safe and affordable manner. In that regard, thermoelectric generators emerge as important renewable energy source with great potential to take advantage of the widely-abundant and normally-wasted thermal energy. Thanks to the advancements of nano-engineered materials, thermoelectric generators’ (TEG) performance and feasibility are gradually improving. However, still innovative engineering solutions are scarce to sufficiently take the TEG performance and functionalities beyond the status-quo. Opportunities exist to integrate them with emerging fields and technologies such as wearable electronics, bio-integrated systems, cybernetics and others. This review will mainly focus on unorthodox but effective engineering solutions to notch up the overall performance of TEGs and broadening their application base. First, nanotechnology’s influence in TEGs’ development will be introduced, followed by a discussion on how the introduction of mechanically reconfigurable devices can shape up the emerging spectrum of novel TEG technologies. © The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. [DOI: 10.1149/2.0081703jss] All rights reserved.

Review—Electrochemical Biosensors Based on ZnO Nanostructures

Abstract: In recent years, electrochemical biosensors based on semiconductor and metal nanostructures have attracted a great deal of attention as new instruments in the healthcare arsenal that could substant ...

Post Cleaning for FEOL CMP with Silica and Ceria Slurries

Abstract: Post cleaning experiments for front end of the line (FEOL) CMP with silica and ceria slurries are carried out on commercial polishers with 300 mm oxide, nitride, and integrated shallow trench isolation (STI) wafers. Considering the charge attraction or repulsion between particles and wafer surface, both acidic and basic clean chemicals are applied at different stages in the post CMP process sequence. Diluted hydrogen peroxide in a non-contact megasonic cleaner is used to remove ceria abrasive particles and polish residues with high efficiency. On-platen buff clean with or without pad conditioning can make an impact on the post CMP cleaning performance. Post CMP cleaning splits are executed in order to evaluate the effectiveness of each of the process steps and their roles in the overall cleaning performance.

Analysis of 2D Transport and Performance Characteristics for Lateral Power Devices Based on AlGaN Alloys

Abstract: In this paper, predicted lateral power device performance as a function of alloy composition is characterized by a standard lateral device figure-of-merit (LFOM) that depends on mobility, critical electric field, and sheet carrier density. The paper presents calculations of AlGaN electron mobility in lateral devices such as HEMTs across the entire alloy composition range. Alloy scattering and optical polar phonon scattering are the dominant mechanisms limiting carrier mobility. Due to the significant degradation of mobility from alloy scattering, at room temperature Al fractions greater than about 85% are required for improved LFOM relative to GaN using a conservative sheet charge density of 1 × 10 13 cm –2. However, at higher temperatures at which AlGaN power devices are anticipated to operate, this “breakeven” composition decreases to about 65% at 500 K, for example. For high-frequency applications, the Johnson figure-of-merit (JFOM) is the relevant metric to compare potential device performance across materials platforms. At room temperature, the JFOM for AlGaN alloys is predicted to surpass that of GaN for Al fractions greater than about 40%.

Increase in Ce3+ Concentration of Ceria Nanoparticles for High Removal Rate of SiO2 in Chemical Mechanical Planarization

Abstract: Ceria nanoparticles (NPs) are used as abrasives for silicon dioxide (SiO2) chemical mechanical planarization (CMP) due to the strong chemical bonds between the Ce3+ ions of ceria NPs and the hydrated silicate species on the surface of SiO2 films. However, the limited concentration of Ce3+ ions in ceria NPs remains a major challenge for this application. Herein, we report a simple strategy to synthesize ceria NPs with high concentrations of Ce3+ ions for enhanced adsorption reactions with silicate anions. Three types of ceria NPs approximately 70 nm in size were synthesized via the aggregation of different sized primary NPs. As the particle size of the primary NPs decreased from 70 nm to 5 nm, the Ce3+ concentration of the ceria NPs increased from 15.6 to 24.0%. The adsorption isotherm fits the Freundlich model and the constants of adsorption capacity (KF) and adsorption intensity (1/n) indicate that the adsorption affinity for silicate anions increased with increasing Ce3+ concentration. The increase in Ce3+ concentration led to an increase in the chemical adsorption between ceria NPs and silicate anions, resulting in a high removal rate of SiO2 during CMP.

Cathodoluminescence and Photoluminescence of YPO4:Pr3+, Y2SiO5:Pr3+, YBO3:Pr3+, and YPO4:Bi3+

Abstract: We are grateful to the German ministry for research and education (BMBF) and to the Foundation of the German economy for generous financial support. We are also grateful to the EPSRC and Technology Strategy Board (TSB) for funding the PURPOSE (TP11/MFE/6/1/AA129F; EP-SRC TS/G000271/1) and CONVERTED (JeS no. TS/1003053/1), PRISM (EP/N508974/1) and FAB3D programs. We are finally grateful to the TSB for funding the CONVERT program.

Review—Critical Considerations of High Quality Graphene Synthesized by Plasma-Enhanced Chemical Vapor Deposition for Electronic and Energy Storage Devices

Abstract: Graphene is a promising electrode material not only due to its intrinsic properties like good electrical conductivity, high mechanical strength and high chemical stability, but also because of its high theoretical surface area of 2630 m2 g−1. In this report, the effect of CVD parameters to the growth of high quality graphene on metal substrates by using plasma enhanced chemical vapor deposition (PECVD) was extensively studied. Interestingly, synthesizing high quality graphene by PECVD technique is not only depending on the CVD parameters, but also depending on the catalysts and its plasma sources. It was found that Ni and Cu are the most favored metal catalysts for PECVD graphene growth. With high solubility of carbon (> 0.1 at. %), Ni effectively promote the growth of multilayer graphene by PECVD. However, large-area synthesis has made relatively inexpensive Cu as one of the most attractive substrates for monolayer graphene growth. Further details on the potential use of different transition metal catalysts in synthesizing graphene and consequently the specific usage of graphene based devices are discussed in this report.