bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding how rapid response systems may improve safety for the acutely ill patient: learning from the frontline
Authors: Mackintosh Nicola , Rainey Helen , Sandall Jane
Published: October 2011

Introduction

Rapid response systems (RRSs) have been introduced to facilitate effective ‘rescue’ of seriously ill patients on hospital wards. While research has demonstrated some benefit, uncertainty remains regarding impact on patient outcomes. Little is known about the relationship between social contexts and the application of the RRS.

Design

This comparative case study of the RRS within the medical services of two UK hospitals used ethnographic methods over a 12-month period in 2009, including observation (ward work and shadowing medical staff = 150 h), interviews with doctors, ward and critical care nurses, healthcare assistants, safety leads and managers (n=35), documentary review and analysis of routine data. Data were analysed using NVivo software.

Results

The RRS reduced variability in recording, recognition and response behaviour. The RRS formalised understandings of deterioration and provided a mandate for escalating care across professional and hierarchical boundaries. However, markers of deterioration not assimilated into risk scores were marginalised and it was harder for staff to escalate care without the ‘objective evidence’ provided by the score. Contextual features (eg, leadership, organisational culture and training) shaped implementation, utilisation and impact of the RRS. Reporting and feedback of audit data enabled learning about ‘selected’ escalation work on the wards. Difficulties with referral upwards and across medical boundaries were reported by junior medical staff.

Conclusion

Locating a RRS within a pathway of care for the acutely ill patient illustrates the role of these safety strategies within the social organisation of clinical work. There is a need to broaden the focus of inquiry from detection and initiation of escalation (where the strategies are principally directed) towards team response behaviour and towards those medical response practices which to date have escaped scrutiny and monitoring.
Co-cyprindiol prescribing in a large, rural general practice in England: Figure 1
Authors: Tandy Rosalind M
Published: October 2011

Objectives

To describe current co-cyprindiol prescribing in a large, rural general practice in England. To specifically investigate whether co-cyprindiol is prescribed within its license and Medicines and Healthcare products Regulatory Agency (MHRA) guidelines. To investigate the effect of a simple, low-cost intervention on the number and appropriateness of co-cyprindiol prescriptions.

Methods

The computerised medical record system in a 17 435 patient general practice was examined to identify individuals prescribed co-cyprindiol. The medical records for each individual identified were examined to see if they satisfied the MHRA guidelines in co-cyprindiol use. Prescribers were then contacted and sent copies of the MHRA guideline. All patients were invited to attend for review. Prescriptions for co-cyprindiol were then re-audited.

Results

Co-cyprindiol comprised 3.4% of total combined oral contraceptive prescriptions. The most common indication was acne (69%).

At baseline, the majority of prescriptions did not meet the MHRA guidelines. Prescriptions that did not meet guidelines tended to have been for longer (32 vs 19.5 months). After the intervention, the number of individuals prescribed co-cyprindiol fell (26 vs 12) and the number of prescriptions that met the guidelines increased (30.7% vs 75%). The largest change was a decrease in inappropriate prescriptions for acne.

Conclusions

In this population, co-cyprindiol was rarely prescribed, though its use often contravened guidelines. Simple interventions can increase appropriateness of prescribing.
Testing relationships: ethical arguments for screening for type 2 diabetes mellitus with HbA1C
Authors: Degeling Chris , Rock Melanie , Rogers Wendy A
Published: October 2011

Since the 1990s, glycated haemoglobin (HbA1C) has been the gold standard for monitoring glycaemic control in people diagnosed as having either type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM). Discussions are underway about diagnosing diabetes mellitus on the basis of HbA1C titres and using HbA1C tests to screen for T2DM. These discussions have focused on the relative benefits for individual patients, with some attention directed towards reduced costs to healthcare systems and benefits to society. We argue that there are strong ethical reasons for adopting HbA1C-based diagnosis and T2DM screening that have not yet been articulated. The rationale includes the differential impact of HbA1C-based diabetic testing on disadvantaged groups, and what we are beginning to learn about HbA1C vis-à-vis population health. Although it is arguable that screening must primarily benefit the individual, using HbA1C to diagnose and screen for T2DM may promote a more just distribution of health resources and lead to advances in investigating, monitoring and tackling the social determinants of health.
The near disappearance of genital warts in young women 4 years after commencing a national human papillomavirus (HPV) vaccination programme
Authors: Read Tim R H , Hocking Jane S , Chen Marcus Y , Donovan Basil , Bradshaw Catriona S , Fairley Christopher K
Published: October 2011

Background

Australia provided free quadrivalent human papillomavirus vaccines to 12–18-year-old girls and women aged ≤26 years from mid-2007 until the end of 2009. After this time, only girls aged 12–13 years had access to free vaccines.

Methods

Before and after the study, of the proportion of new patients attending Melbourne Sexual Health Centre from mid-2004 to mid-2011, diagnosed with genital warts (GW) by risk group.

Results

From July 2004 to June 2011, 52 454 new patients were seen at Melbourne Sexual Health Centre and 5021 (9.6%, 95% CI 9.3% to 9.8%) were diagnosed with GW. From July 2004 to June 2007, the proportions with GW either increased or did not change in all groups. Comparing the two 12-month periods of 2007/2008 and 2010/2011, GW declined in women under 21 years from 18.6% to 1.9% and in heterosexual men under 21 years from 22.9% to 2.9%. The ORs per year for diagnosis of GW adjusted for number of sexual partners from July 2007 until June 2011 in women and heterosexual men <21 years were 0.44 (95% CI 0.32 to 0.58) and 0.42 (95% CI 0.31 to 0.60), respectively. There was no significant change in GW in women ≥30 years (OR 0.97, 95% CI 0.84 to 1.12), heterosexual men ≥30 years (OR 0.97, 95% CI 0.89 to 1.06) or in homosexual men (OR 0.95, 95% CI 0.85 to 1.07).

Conclusion

The dramatic decline and near disappearance of GW in women and men under 21 years of age, 4 years after commencing this programme, suggest that the basic reproductive rate has fallen below one.
Magnetically Modified Dye Sensitized Solar Cells
Authors: Lee Garett G. , Leddy Johna
Published: October 2011

Magnetically modified, dye sensitized, n-type semiconductor electrodes were examined as a case study for magnetic field effects on electron transfer reactions in electrochemical power systems. Magnetic field effects arise through kinetics and mass transport; magnetic fields have negligible influence on system thermodynamics (i.e., no effects on open-circuit potential). Enhancements in the photocurrent response of dye sensitized TiO2 semiconductor electrodes are observed.
Synthesis of a Cu2ZnSnS4 (CZTS) Absorber Layer and Metal Doped ZnS Buffer Layer for Heterojunction Solar Cell Applications
Authors: Inamdar Akbar I. , Jeon Ki-Yong , Woo Hyeon seok , Jung Woong , Im Hyunsik , Kim Hyungsang
Published: October 2011

A novel synthetic strategy was employed to fabricate a Cu2ZnSnS4 (CZTS) absorber layer using a quaternary compound target which has similar properties to that of copper indium gallium selenide (CIGS). A conventional R-F magnetron sputtering system was used to fabricate the CZTS absorber layers on glass substrates. The films were rapidly thermally annealed at 500 °C in a nitrogen atmosphere for 20 minutes to improve their crytallinity. The formation of a kesterite structure was confirmed using X-ray diffraction measurements. The improved crytallinity of the CZTS was observed with (112) oriented phase. The band gap of the as-deposited and annealed films was found to be 1.97 and 1.55 eV respectively. The films stoichiometry and morphology were observed using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) measurements. In addition; buffer layer of ZnS which was doped with metal elements; was fabricated by using a chemical bath deposition (CBD) technique.
Nitride Semiconductors: Why they Work in Optoelectronic Devices
Authors: Moustakas Theodore D.
Published: October 2011

GaN and its alloys with AlN and InN, grown heteroepitaxially on sapphire and other substrates, have a high concentration of point and line defects. In this paper I am addressing the fundamental question as to why such semiconductors produce very efficient minority carrier optoelectronic devices (LEDs, lasers etc). One fundamental difference between the traditional semiconductors (silicon and III-V compounds) and nitride semiconductors is that the chemical bonds in the former are mostly covalent while are strongly ionic in the later. This results in the bunching of the surface states in GaN and its alloys with AlN and InN near the band edges. This implies that that the surface states in free surfaces and the dangling bonds in edge dislocations are not expected to be non-radiative recombination centers but traps. Besides this unique property the InGaN and AlGaN alloys can be made to have strong band structure potential fluctuations, leading to exciton localization and thus efficient radiative recombination.
Plasmon-Enhanced Near-Green Light Emission from InGaN/GaN Quantum Wells
Authors: Paiella Roberto , Henson John , DiMaria Jeff , Dimakis Emmanouil , Li Rui , Minissale Salvatore , Dal Negro Luca , Moustakas Theodore D.
Published: October 2011

The plasmonic excitations of square-periodic arrays of silver nanocylinders are used to increase the radiative efficiency of nearby InGaN/GaN quantum wells emitting at near-green wavelengths. These nanostructures allow for an accurate control of the plasmonic resonance wavelength, scattering-absorption ratio, and electromagnetic near-field enhancement via geometrical tuning. In turn, these properties are found to play a critical role in the measured light-emission efficiency enhancements.
Effect of Interface Polarization Charge on GaN/SiC Separate Absorption and Multiplication Avalanche Photodiodes
Authors: Shen Paul H. , Sampath Anand V. , Zhou Quigui , Campbell Joe , Wraback Michael
Published: October 2011

A III-Nitride/ SiC separate absorption and multiplication avalanche photodiode (SAM-APD) offers a novel approach for fabricating high gain photodetectors with tunable absorption over a wide spectrum from the visible to deep ultraviolet. However, unlike conventional heterojunction SAM APDs, the formation of polarization-induced charge at the hetero-interface arising from spontaneous and piezoelectric polarization can dramatically affect the performance of this detector. In this paper we report on the role of this interface charge on the performance of GaN/SiC SAM APDs.
Circular and Rectangular Via Holes Formed in SiC via Using ArF Based UV Excimer Laser
Authors: Liu Lu , Chang C. Y. , Wu Wenhsing , Pearton S. J. , Ren F.
Published: October 2011

Circular via holes with diameters of 10, 25, 50 and 70 μm and rectangular via holes with dimensions of 10 μm × 100 μm, 20 μm × 100 μm and 30 μm × 100 μm and drilled depths between 105 and 110 μm were formed in 300 μm thick bulk 4H-SiC substrates by ArF based UV laser drilling (λ = 193 nm) with a pulse width of ~30 nsec and a pulse frequency of 100 Hz. The drilling rate was linearly proportional to the fluence of the laser, however, the rate decreased for the larger via holes. The laser drilling produces much higher etch rates (229-870 μm/min) than conventional dry etching (0.2-1.3 μm/min) and the via entry can be tapered to facilitate subsequent metallization.
Fabrication and Characterization of Self-Aligned InAlAs/InGaAsSb/InGaAs Double Heterojunction Bipolar Transistors
Authors: Lo Chien-Fong , Chang C. Y. , Chen S.-H. , Chang C.-M. , Wang S.-Y. , Chyi J.-I. , Kravchenko I. I. , Pearton S. J. , Ren F.
Published: October 2011

A trilevel resist system was employed to fabricate self-aligned, submicron emitter finger In0.52Al0.48As/In0.42Ga0.58As0.77Sb0.23/ In0.53Ga0.47As double heterojunction bipolar transistors (DHBTs). Selective wet-etchants were used to define the emitter fingers and to form an InGaAs guard-ring around the emitter fingers. Due to the low energy bandgap of the InGaAsSb base layer and type II base-collector junction, a low turn-on voltage of 0.38 V at 1 A/cm2 and a high dc current gain of 123.8 for a DHBT with a 0.65 x 8.65 µm2 emitter area were obtained. A unity gain cut-off frequency (fT) of 260 GHz and a maximum oscillation frequency (fmax) of 485 GHz at JC = 302 kA/cm2 were achieved.
Thermal Simulation of 193 nm UV-Laser Lift-Off AlGaN/GaN High Electron Mobility Transistors Mounted on AlN Substrates
Authors: Kang Tsung-Sheng , Lo Chien-Fong , Liu Lu , Finch Rob , Ren F. , Wang Xiao-Tie , Douglas Erica , Pearton S. J. , Hung Shao-Tsu , Chang Chi-Jun
Published: October 2011

A finite element simulation was used to estimate the temperature rise of laser lift-off AlGaN/GaN high electron mobility transistors (HEMTs) mounted on AlN substrates via silicone elastomer under various conditions of power density on the transistor and for a range of elastomer thicknesses. The thermal response was compared to HEMTs fabricated on SiC and sapphire substrates. The maximum temperature of the transistor occurred in the gate area at a power level of 15W, and was only 25K higher than HEMTs fabricated on SiC. The transit time required for steady-state temperature of the flip-chip bonding device is in the range of a millisecond, which is faster than that of most power switch applications.
The Reliability Study and Device Modeling for p-HEMT Microwave Power Transistors
Authors: Liu Szu-Ling , Chang H.M. , Chang Tsu , Kao Hsuan-Ling , Cheng Chun-Hu , Chin Albert
Published: October 2011

In this paper, the commercial 0.5-μm AlGaAs/InGaAs/GaAs pseudo-morphic high electron mobility transistors were subjected to both high-drain voltage and high-temperature stresses for investigating reliability issues. The results reveal that the stress-induced trapping phenomena near two-dimensional electron gas layer should be responsible for the different drain current collapses. The decay level of the DC and the small-signal characteristics increases with the stress voltage and/or the operation temperature. The self-consistent model was established through the de-embedded and the non-linear fitting processes, which can be used to estimate the DC and RF small-signal characteristics degradation under high-drain voltage and high-temperature stress.
Combination of the Opposing Effects of Silver Nanoparticles and Peptide Nucleic Acids on Dye-Sensitized Solar Cells to Enhance their Respective Positive Influence
Authors: Loew Noya , Ikenouchi Shun , Ihara Manabu
Published: October 2011

We successfully combined the opposing effects of both silver nanoparticles (AgNP) and long double stranded peptide nucleic acids (dsPNA). By using nanoparticles (AgNP-PNA) modified with short PNA with a 7mer complementary sequence to one of the long strands of the dsPNA, formation of a triplex of the short PNA modification of the AgNP-PNA and the dsPNA is possible, ensuring a close proximity of dsPNA and nanoparticles. With this, we achieved an increase in short circuit current from 6.31 mA/cm2 (standard-type) to 8.48 mA/cm2 (dsPNA + AgNP-PNA). In this study, we also introduced a new method of evaluation using photocurrent generation profiles.
Graphene/SiC/Si FETs with SiCN Gate Stack
Authors: Suemitsu Tetsuya , Kubo Makoto , Handa Hiroyuki , Takahashi Ryota , Fukidome Hirokazu , Suemitsu Maki , Otsuji Taiichi
Published: October 2011

Graphene-on-silicon field-effect transistors (GOSFETs) are studied as a candidate of next generation transistors. Graphene is formed on SiC layers grown on Si substrates. As well as the channel material, the gate stack is also a key component of FETs. In this study, SiCN deposited by plasma-enhanced chemical vapor deposition (PECVD) using hexamethyldisilazane (HMDS) vapor is studied. During PECVD, hydrogen is used as a carrier gas in addition to HMDS vapor. This becomes an advantage in the graphene process because hydrogen has cleaning effect on graphene surface. To verify this effect, SiCN gate stack is applied to the graphene on SiC substrates. FETs with SiCN gate stack exhibit clearer ambipolar characteristics and larger drain current density than FETs with conventional SiN gate stack. The SiCN gate stack is also applied to GOSFETs. Resulting devices also exhibit ambipolar characteristics and larger current density than previously reported GOSFETs with SiN gate stack.
Investigation of Galvanic Corrosion Characteristics between Tantalum Nitride and Poly Silicon in Dilute HF Solutions
Authors: Govindarajan Rajkumar , Keswani Manish , Raghavan Srini
Published: October 2011

Galvanic corrosion characteristics between poly-Si and tantalum nitride (TaN) (area ratio 1:1 and 1:4) have been investigated in very dilute HF solutions (0.01 to 0.05%) containing controlled levels of dissolved oxygen. The increase in exposed cathode (metal) area as well as aeration results in higher corrosion of poly-Si. In de-aerated HF solutions (less than 0.5 ppm of O2), irrespective of the area ratio, there appears to be no silicon loss. Morphological changes on poly-Si due to galvanic corrosion have been characterized using Scanning Electron Microscopy.
Challenges of Wafer Surface Preparation in Advanced Technologies
Authors: Ku Scott , Yeh Matt , Huang K. B. , Yang C. M. , Chen C.C. , Chuang J. P. , Jang S.M. , Huang David
Published: October 2011

Advanced technology nodes introduce new module processes, materials and integrated flow scheme to drive device performance, such as epitaxial SiGe, high-k metal gate (HKMG) or III-V substrate materials [1]. Conventional wet cleaning technologies can not fulfill requirements of new generational devices competently in such novel fields [2]. A case is SiGe epitaxial process prefers to grow on hydrogen-terminated surface of silicon wafer, and oxygen control in deionic water and cleaning aqueous solutions are most addressed and studied. In this presentation, the focuses are on wafer surface preparation for SiGe and HKMG applications and challenges of physcial force cleaning for nano devices.
Development of a Wet Silicon Removal Process for Replacement Metal Gate and Sacrificial Fin
Authors: Suhard Samuel , Sebaai Farid , Pacco Antoine , Veloso Anabela , Carbonell Laureen , Claes Martine , Struyf Herbert , Mertens Paul W. , De Gendt Stefan
Published: October 2011

Tetra Methyl Ammonium Hydroxide (TMAH) was investigated for the selective removal of polysilicon in replacement metal gate (RMG) gate-last integration flow. In such application no polysilicon residues are tolerated. Therefore the TMAH process was developed using the best possible conditions by fine tuning the temperature (70ºC), concentration (5%) and process at tool level. A thorough study was conducted in order to understand the possible causes of polysilicon residues such as implantation condition (boron) and influence of the dielectric layer (SiON, SiO2, TiN) on the crystal orientation of the polysilicon. The resulting TMAH process was successfully transferred to other dummy silicon approach on TiN such as sacrificial fin. In the latter case the amorphous silicon removal was proven to be more selective towards TiN than a dry approach.
Integrated Experimental and Numerical Study of Thermomechanical Resist Removal-Cleaning Performance Using Cryogenic Micro-Solid Nitrogen Spray
Authors: Ishimoto Jun , Tan Daisuke , Oh U , Kubota Tomohiro , Samukawa Seiji
Published: October 2011

The fundamental characteristics of the resist removal-cleaning system using cryogenic micro-solid nitrogen spray flow are investigated by a new type of integrated measurement and numerical technique. It can be numerically predicted that the resist removal performance is improved by the scraping effect of impinging micro-solid nitrogen particle fragment in the narrow section between the resist. Furthermore, it is numerically and experimentally founded that the hybrid interactive effects of fluid mechanical force by impingement of micro solid particle and thermomechanical force due to ultra-high heat transfer characteristics contribute to the resist removal-cleaning process.
Processing and Characterization of GaSb/High-k Dielectric Interfaces
Authors: Hwang Euichul , Eaton Craig , Mujumdar Salil , Madan Himanshu , Ali Ashkar , Bhatia Divij , Datta Suman , Ruzyllo Jerzy
Published: October 2011

To obtain the suitable GaSb surface for high-k dielectric integration, the chemical and structural analysis were performed by x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The chemical analysis indicates the effective native oxide removal from GaSb surface and the resulting surface is slightly antimony rich. The structural study reveals that the surface morphology becomes rough upon the reexposure to air after the HCl-based surface treatment. GaSb metal-oxide semiconductor capacitors (MOSCAPs) with 5 nm Al2O3 by atomic layer deposition (ALD) were fabricated and electrically characterized before and after forming gas anneal (FGA).
Formation of Pyramidal Etch Pits Induced by Metallic Particles on Ge(100) Surfaces in Water
Authors: Arima Kenta , Kawase Tatsuya , Nishitani Keisuke , Mura Atsushi , Kawai Kentaro , Uchikoshi Junichi , Morita Mizuho
Published: October 2011

We demonstrate that pyramidal etch pits composed of (111) micro facets are formed on single-crystalline Ge(100) surfaces when the Ge samples with metallic particles are immersed into water. The mechanism behind this anisotropic etching is the enhanced oxidation of Ge around metallic particles by the catalytic activity of noble metals to reduce dissolved oxygen (O2) to water molecules, and the subsequent removal of the oxide in water due to the soluble nature of Ge oxides. This enhanced etching of Ge surfaces is observed not only with metallic particles but also with a metallic thin film. The results insist that remaining metallic contaminants can roughen Ge surfaces during a rinse process with water, which will be important to design wet cleaning processes for Ge wafers.
Drying Performance of Single IPA Dryer to Prevent Pattern Collapse and Watermark
Authors: Eom Daehong , Kim Kyunghyun , Shin Yugyun
Published: October 2011

Watermark and pattern collapse are easily affected by wetting properties of wafer surfaces and pattern size. Also, these issues are strongly dependent on types of dryer, IPA vapor or liquid dryer. Using the IPA liquid dryer, watermark can easily controlled regardless of wafer types and wetting properties. However, in the case of IPA vapor dryerm watermark is easily affected by wetting properties of wafer surface.
A New Cleaning Technology Using the Effect of Freezing Water on Wafer Surface
Authors: Miya Katsuhiko , Fujiwara Naozumi , Kato Masahiko , Izumi Akira
Published: October 2011

In this paper, effectiveness of freezing process on particle removal efficiency (PRE) for various sizes and polycrystalline silicon line damages was studied by a method which consists of freezing and melting water film on the wafer. It was found that this sequence, freezing and melting process, could remove particles, especially for small-sized particles (e.g. 40-nm particles) with high efficiency, without any damages on 37-nm polycrystalline silicon lines and material loss.
Nano Gas Cluster Dry Cleaning for Damage Free Particle Removal
Authors: Kim Min-Su , Kang Bong-Kyun , Lee Seung-Ho , Yoon Deok-Joo , Choi Hoomi , Kim Ho-Joong , Kim Tae-Sung , Park Jin-Goo
Published: October 2011

CO2 gas cluster cleaning process for nano particles removal without pattern damage was investigated. Gas cluster cleaning process was performed for generating the nano-sized gas cluster in the vacuum chamber. When pressurized CO2 gas was passed through the convergence-divergence (C-D) nozzle, the high speed and high energy gas clusters were generated. The cleaning force of CO2 gas cluster is related to flow rate of the gas and gap distance between the nozzle and substrate. In our studies, the optimum gas flow rate and gap distance for nano-sized particles removal was found, respectively. Pattern damage tests of the poly-Si and a-Si pattern were also evaluated by SEM images. No pattern damages were observed at these optimum conditions.
PR and BARC Wet Strip in BEOL Patterning Using a UV-Enabled Aqueous Process
Authors: Kesters Els , Le Quoc Toan , Lux Marcel , Vereecke Guy , Struyf Herbert , De Gendt Stefan
Published: October 2011

Conventional plasma strip processes are prone to cause damage to advanced porous low-k materials. Therefore, all-wet processes are gaining a renewed interest for the removal of post-etch photoresist (PR) and Bottom Anti Reflective Coating (BARC) in Back-End-of-Line (BEOL) semiconductor manufacturing. A two step process with a UV pre-treatment and an ozonated strip process is considered. The UV pre-treatment under O2 at high temperature enhances PR and BARC removal. With a subsequent fully aqueous ozone wet strip, complete removal is feasible.
Surface Contamination Removal from Si PV Substrates Using A Biodegradable Chelating Agent and Detection of Cleaning Endpoints Using UV/VIS Spectroscopy
Authors: George Mark , Treichel Helmuth , Bohling David , Goldstein Avery , Litvak Herbert , Ostrowski Sara , Mowat Ian , Kern Werner
Published: October 2011

The continued pressure for increasing c-Si solar efficiency is generating many innovative and novel approaches. In this manuscript we present the results of a chemical cleaning approach for targeted removal of efficiency degrading metallic contaminants. The application of this cleaning approach, in both alkaline and acidic cleaning processes has demonstrated 0.2 to 0.3% absolute cell efficiency improvement for both mc-Si and c-Si production lines. This improvement is not dependent on cell architectures, but addresses a universal complication arising from crystalline silicon wafering manufacture. We also disclose the potential of utilizing this chemistry to enable a spectroscopic method for real time monitoring of trace metal loading in the cleaning baths and by extension a method to provide a process endpoint detection based on metallic loading levels in aqueous solutions.
(Invited) High Power Semiconductor Devices for FACTS: Current State of the Art and Opportunities for Advanced Materials
Authors: Marinella Matthew J. , Atcitty Stanley , DasGupta Sandeepan , Kaplar Robert J. , Smith Mark A.
Published: October 2011

Flexible AC Transmission Systems (FACTS) use advanced power electronics to minimize reactive power loss on the grid. Power devices used in FACTS systems must be capable of switching several thousand amps at voltages of 1-10 kV. Traditionally, these systems have relied on silicon thyristors, but recently have also began to incorporate insulated gate bipolar transistors. FACTS systems present an opportunity for emerging SiC and GaN power transistors, which offer major efficiency gains. However, for these advanced materials to be considered for use in high consequence grid level systems like FACTS controllers, excellent reliability must be demonstrated.
(Invited) Supercapacitor/Battery Hybrids for Energy Harvesting Applications
Authors: Peckerar Martin , Zhao Wei , Dilli Zeynep , Dornajafi Mahsa , Lowy Daniel , Potbhare Siddharth
Published: October 2011

This paper demonstrates a a system capable of harvesting radio-frequency energy from the environment, rectifying this energy, boosting the resulting voltage across a load and using this rectified signal to charge a battery and a super-capacitor hybrid system. Each of the components of this system (antenna, diode rectifier/voltage multiplier/storage medium) will be discussed and a power harvesting efficiency of 11% will be demonsrated
(Invited) Assessment of Durable SiC JFET Technology for +600° to -125° Integrated Circuit Operation
Authors: Neudeck Philip , Krasowski Michael , Prokop Norman
Published: October 2011

Electrical characteristics and circuit design considerations for prototype 6H-SiC JFET integrated circuits (ICs) operating over the broad temperature range of -125 °C to +600 °C are described. Strategic implementation of circuits with transistors and resistors in the same 6H-SiC n-channel layer enabled ICs with nearly temperature-independent functionality to be achieved. The frequency performance of the circuits declined at temperatures increasingly below or above room temperature, roughly corresponding to the change in 6H-SiC n-channel resistance arising from incomplete carrier ionization at low temperature and decreased electron mobility at high temperature. In addition to very broad temperature functionality, these simple digital and analog demonstration integrated circuits successfully operated with little change in functional characteristics over the course of thousands of hours at 500 °C before experiencing interconnect-related failures. With appropriate further development, these initial results establish a new technology foundation for realizing durable 500 °C ICs.
(Invited) Modeling and Simulation of Silicon Carbide Power Systems
Authors: Goldsman Neil , Potbhare Siddharth , Akturk Akin , Salemi Shahrzad , Lelis Aivars
Published: October 2011

Silicon Carbide (SiC) based electronics are extremely promising for use in power systems as a result of their large band-gap and ability to grow a gate oxide. To facilitate the development of SiC based circuits, we need to develop new design tools that help to extract the physics of the devices, as well as to quantify the electrical and thermal performances for improved design. This paper discusses various modeling methods, from the atomic level to the circuit level, to help understand and quantify both the electrical and thermal characteristics of new circuits using SiC devices.
(Invited) Packaging and Modeling of SiC Power Modules
Authors: Schirmer Kit C. , Rowden Brian , Mantooth Homer A. , Ang Simon S. , Balda Juan C.
Published: October 2011

This paper presents the latest advancements in silicon carbide (SiC) power module packaging. Die attach methods, passivation techniques, and module packaging techniques for multiple-chip power modules are described. The most recent work involving high voltage/high current modules for a SiC fault current limiter rated at 8 kV and 400 A continuous current is described. A roadmap to address outstanding challenges is proposed.
(Invited) Effect of Threshold-Voltage Instability on SiC Power MOSFET High-Temperature Reliability
Authors: Lelis Aivars , Green Ronald , Habersat Daniel
Published: October 2011

A review of recent work on the effect of threshold-voltage instability on the reliability of SiC power MOSFETs is presented. Significant increases in the instability of the ID-VGS characteristics due to ON-state current stressing are similar in nature to increases caused by high-temperature bias stressing. Devices stressed by elevated temperature alone exhibited very little instability compared with devices stressed with both temperature and applied bias. These results, along with other results in the literature, suggest that this increase in threshold voltage instability at elevated temperature is due to the activation of additional near-interfacial gate oxide traps related to an O-vacancy defect known as an E′ center. It is important to develop improved processing methods to decrease the number of precursor oxide defect sites, since an increased negative shift can give rise to increased leakage current in the OFF-state and potential device failure if proper precautions are not met to provide an adequate margin for the threshold voltage.
(Invited) Toward the Reduction of Performance-Limiting Defects in SiC Epitaxial Substrates
Authors: Ohtani Noboru
Published: October 2011

Reduction of the performance-limiting defects in SiC epitaxial substrates is indispensable to further penetration of SiC devices into the power device markets. This paper provides an opportunity to overview the current issues in SiC epitaxial substrates, focusing on dislocation-related problems. Structural defects such as threading screw dislocations (TSDs) and basal plane dislocations (BPDs) as well as surface morphological defects on the epitaxial layers due to dislocations are of current concern. The paper reviews recent important results regarding these defects from the viewpoint of crystal growth and discusses their causes and formation mechanisms.
(Invited) The Resurgence of III-N Materials Development: AlInN HEMTs and GaN-on-Si
Authors: Laboutin Oleg , Cao Yu , Wang Ronghua , Li Guowang , Jena Debdeep , Xing H. , Lo Chien-Fong , Liu Lu , Pearton S. J. , Ren F. , Johnson Wayne
Published: October 2011

Heterostructure devices based on the AlInN material system have demonstrated unprecedented high frequency performance but are still limited by materials issues. Likewise, improved crystal growth schemes are envisioned as a key component in the realization of GaN-on-Si high voltage devices for power electronics applications. This work presents materials optimization results from MOCVD growth of quaternary barrier AlInGaN/AlN/GaN HEMTs formed on sapphire and SiC substrates and also a study of AlN nucleation and subsequent GaN growth for crack-free films on silicon (111).
Theoretical Study of Ge Dangling Bonds in GeO2 and Correlation with ESR Results at Ge/GeO2 Interfaces
Authors: Houssa Michel , Pourtois Geoffrey , Scalise Emilio , Afanas'ev Valery , Stesmans Andre
Published: October 2011

The g-tensors of dangling bonds at defective Ge atoms in GeO2 are computed using density functional theory. The isotropic g-values of these defects are found to increase with the number of Ge backbonds. By comparing these calculations with the isotropic g-value of a Ge-related defect at Ge/GeO2 interfaces, recently observed by electron spin resonance and electrically detected magnetic resonance experiments, we tentatively identify this defect as a Ge2O≡Ge• center, i.e. a dangling bond on a Ge atom backbonded to two Ge atoms and one O atom, likely present near the Ge/GeO2 interface. The interaction of this defect with molecular hydrogen is investigated using first-principles molecular dynamics simulations. Our simulations predict that the Ge dangling bond can be hardly passivated by H2 molecules, in agreement with the electron spin resonance study.
Light Effects on Charge Trapping and Detrapping of nc-ZnO Embedded ZrHfO High-k MOS Nonvolatile Memories
Authors: Luo Bingqing , Lin Chen-Han , Kuo Yue
Published: October 2011

MOS capacitors containing the nanocrystalline ZnO embedded Zr doped HfO2 high-k gate dielectric film integrated with the indium tin oxide gate electrode have been fabricated and characterized under the dark and light exposure conditions for nonvolatile memory properties. When measured in dark, the capacitor had a large charge storage capacity showing a counterclockwise capacitance-voltage hysteresis. When exposed to the light, the memory capacity was increased. The generation and transfer of electrons and holes in and from the nanocrystalline ZnO under the light exposure condition are responsible for the memory window change and charge retention characteristics.
Evaluation of Al2O3 Films for MANOS Memory Device with Oxygen Infusion by Gas Cluster Ion Beam
Authors: Nagata Kohki , Hashiguchi Hiroki , Yamagichi Takuya , Ogura Atsushi , Oji Hiroshi , Son Jin-Young , Hirosawa Ichiro , Tanaka Yoshitsugu , Hirota Yoshihiro , Gumpher John , Yamashita Koji
Published: October 2011

Properties of Al2O3 as blocking layer of MANOS memory device were investigated and effects of O infusion by GCIB process were discussed. By introduction of GCIB process, electrical properties were improved such as increasing of program window. GCIB process was able to modify film density and band-gap energy, which was limited to several nm from the surface. The variation of band structure induced by the oxygen infusion contributed to the improvement of electrical properties because reduction of electrical field suppressed F-N tunneling during erase operation.
Structural, Optical and Electrical Properties of Thin Films of Lanthanum Aluminum Oxide Synthesized by Spray Pyrolysis
Authors: Meza-Rocha Abraham N. , Zaleta-Alejandre Efrain , Balderas Rafael , Rivera Zacarias , Perez-Arrieta M. Leticia , Falcony Ciro
Published: October 2011

The structural, optical and electrical properties of spray pyrolysis deposited lanthanum aluminum oxide are reported. The films were deposited from a spraying solutions of lanthanum nitrate and aluminum acetylacetonate in N, N- dimethylformamide using an ultrasonic generator on (100) Si substrates. The substrate temperature was in the 550-650°C range. The thickness was in below 300 Aå. The optical band gap was 5.3 eV, and the refractive index at 630 nm was up to 1.62 depending of the relation lanthanum-aluminum. The electrical characteristics of the films were determined from the capacitance and current versus voltage measurements of metal-oxide-semiconductor (MOS) structures incorporating them. A dielectric constant in the 6-12 range, interface states density of the order of 1012 X 1/eV cm2 as well as breakdown fields higher than 3 MV/cm were determine in this way.
In0.7Ga0.3 as Tunneling Field-Effect-Transistors with LaAlO3 and ZrO2 High-k Dielectrics
Authors: Xue Fei , Zhao Han , Chen Yen-Ting , Wang Yanzhen , Zhou Fei , Lee Jack
Published: October 2011

We investigated the device structure and fabrication process of In0.7Ga0.3As tunneling field-effect-transistors (TFETs) with atomic-layer-deposited (ALD) high-k dielectrics. We compared the device performance of In0.7Ga0.3As TFETs with p++/i and p++/n+ tunneling junctions. TFETs with p++/n+ tunneling junction exhibit higher drive current and lower subthreshold swing than devices with p++/i junction. Device characteristics of InGaAs TFETs with different high-k dielectrics LaAlO3 and ZrO2 have also been studied. In0.7Ga0.3As TFETs with ZrO2 (EOT~0.8 nm) exhibit subthreshold swing of 80mV/dec and drive current of 44 mA/mm (at Vg-Vth=2 V).
Si3N4 as a Useful Dielectric for InGaAs MIS Stacks
Authors: Krylov Igor , Gavrilov A. , Cohen Shimon , Ritter Dan , Eizenberg Moshe
Published: October 2011

Fully unpinned behavior of the Si3N4 (PECVD)/InGaAs system with Dit ~ 10^12 eV-1 cm-2 was observed after 400C 30 min annealing. No influences of ambient gas treatment conditions or treatment order relative to gate metal deposition on C-V behavior and Dit values were observed. Influence of the annealing temperature on C-V behavior and Dit was explored in the range 300C - 500C. It was found that 400C anneal shows the best C-V behavior and the lowest Dit values for the Si3N4 (PECVD)/InGaAs system. Slightly better results of the accumulation frequency dispersion and flat-band hysteresis were observed for forming gas treatment compared to N2/vacuum anneals.
EOT Scaling and Flatband Voltage Shift with Al Addition into TiN
Authors: Nakamura Genji , Hasegawa Toshio , Consiglio Steven , Amano Fumitaka , Luong Vinh , Trickett Ying , Wajda Cory S. , Clark Robert D. , Leusink Gert J. , Maekawa Kaoru
Published: October 2011

We present both EOT scaling and flatband voltage (Vfb) shift for Hf-based high-k containing metal-oxide-semiconductor capacitors (MOSCAPs) due to Al addition into the TiN metal gate. The metal gate was deposited using chemical vapor deposition (CVD) and the Hf-based high-k films were deposited using CVD or atomic layer deposition (ALD) in 300nm deposition chambers. We found that the Vfb shift amount by Al addition into TiN depends on the high-k film (HfO2 vs. HfSiON) as the shift for the HfO2 containing stack was greater than that in the HfSiON containing stack. We also examined the effect of the thermal budget of the MOSCAP flow on the Vfb shift by Al addition into TiN. We observed that the Vfb shift direction by Al addition into TiN was dependant on the MOSCAP flow (gate-first vs. gate-last like) and this Vfb shift behavior can be explained by Al-based dipole and oxygen vacancy models.
Electrical Characteristics and Temperature Response of Al2O3 Gate Dielectrics with and without Nitric Acid Compensation
Authors: Lin Chien-Chih , Hwu Jenn-Gwo
Published: October 2011

In this paper, the Al2O3 gate dielectrics prepared by the in situ oxidation of sputtered Al in Ar/O2 ambient at room temperature and then without and with HNO3 compensation are demonstrated. It was found that the saturation substrate injection currents of MOS capacitors with P-type Si substrate at the positive bias region exhibit perimeter-dependent characteristics due to the enhanced fringing field effect. The temperature responses of perimeter-dependent saturated currents are different between two samples. The sample with HNO3 compensation shows regular dependence of substrate current on ni, but the one without HNO3 compensation exhibits additional current components come from oxide nonuniformity and interface trap density. The gate leakage current density at the negative bias region and the time-dependent dielectric breakdown reliability at 25 oC and 125 oC of Al2O3 capacitors can be improved by utilizing HNO3 compensation. It is believed that the HNO3 compensation is beneficial to the improvement of the SiO2/Si interface and the quality of the Al2O3/SiO2 oxide stacks.
Conduction Currents and Paramagnetic Defect Centers in UV-Illuminated Silicon Nitride Films
Authors: Kobayashi Kiyoteru , Ishikawa Kokichi
Published: October 2011

We investigated the effects of thermal annealing on both the conduction current and the paramagnetic K0 centers induced by exposing LPCVD silicon nitride films to 4.9 eV ultraviolet (UV) illumination. The current component induced by UV illumination decayed by the thermal annealing at 150 and 240 °C. UV illumination following the 240 °C annealing induced the current increase once again. The UV-induced current increase is a reversible phenomenon. The current densities after UV exposure and after the subsequent thermal annealing were obviously dependent on the density of the UV-induced paramagnetic defects. We proposed that the UV-induced paramagnetic defects acted as generation centers of electron-hole pairs in the nitride films and the creation of the paramagnetic defects is responsible for the UV-induced current increase.
High Performance Cu-doped SiO2 ReRAM by a Novel Chemical Soak Method
Authors: Chin Fun-Tat , Yang Wen-Luh , Chao Tien-Sheng , Chang Yuan-Ming , Lin Li-Min , Liu Sheng-Hsien , Lin Chia-Hsiung
Published: October 2011

In this paper, a novel chemical soak method is proposed to fabricate a Cu-doped SiO2 ReRAM device. This method can easily fabricate a lightly Cu-doped SiO2 film and effectively improve the reliability of the conventional Cu-doped SiO2 ReRAM device. A reproducible bipolar switching characteristic with set/reset voltage (ca. 2.5 V/ -0.7 V) is performed in this device and the electrical conduction in HRS and LRS are related to Poole-Frenkel and Ohmic conduction, respectively. Excellent performance in terms of high on/off ratio (~106), narrow range distribution of set and reset voltages, stable data retention, and up to 110 times switching cycles has been achieved by this novel chemical soak method for Cu-doped SiO2 ReRAM device.
Monolithic Microphotonic Integration on the Silicon Platform
Authors: Kimerling Lionel C. , Michel J.
Published: October 2011

Photonic integration in ULSI electronic circuits contributes three new functionalities that are critical to performance scaling: i) power efficient, global interconnection, ii) high bandwidth density chip-chip communication, and iii) optical signal processing. With the transition to parallel chip architectures, efficient communication among processing nodes can become a limiting factor to both programming and performance. A photonic communication layer can provide distance independent, low latency interconnection with efficient broadcast capability. On-chip photonic signal channels can provide wavelength division multiplexed, photonic pins with >100x improvement in I/O bandwidth density over ball grid arrays. Monolithic integration of these capabilities in the CMOS process flow can be achieved with Ge active devices (photodetectors, modulators, lasers) and Si/SiON passive components (waveguides, resonators, couplers). Process integration can be achieved with both FEOL and BEOL strategies.
(Invited) Restructuring of Memory Layer in Electrical System and its Novel Evolution with Nonvolatile Logic
Authors: Endoh Tetsuo
Published: October 2011

Future semiconductor memories must increase its memory capacity while increasing operation speed and decreasing power consumption. Especially from the perspective of decreasing the power consumption of the system, the improvement in performance of nonvolatile memories is in strong demand. From this background, we introduce novel types of nonvolatile semiconductor memory, which uses storage information other than the conventional charge of the electrons and we also introduce the progress of stacked type vertical NAND type memories for large data capacity. In addition, from the perspective of super low power consumption systems, we discuss the trend of nonvolatile logic, which combine Spintronic devices with semiconductor CMOS logic in order to realize higher level of low power system.
(Invited) High-K Dielectrics / High-Mobility Channel MOSFETs
Authors: Lee Jack , Xue Fei , Chen Yen-Ting , Wang Yanzhen , Zhou Fei
Published: October 2011

We have systematically investigated the effect of process annealing sequence, channel thickness/doping concentration and high-k gate stacks on device performance of surface channel InGaAs metal-oxide-semiconductor field-effect-transistors (MOSFETs). In this paper, high performance InGaAs MOSFETs and tunneling field-effect-transistors (TFETs) with optimized device structure and process are presented.
(Invited) Opportunity for Phase-Controlled Higher-k HfO2
Authors: Toriumi Akira , Nakajima Yasuhiro , Kita Koji
Published: October 2011

Structural phase transformation of pure-HfO2 films to higher-k phase (cubic or tetragonal phase) is discussed in terms of both doping effect and dynamic post-deposition annealing (PDA). Y2O3 and SiO2 were doped into HfO2, while the rapid thermal treatment was performed, respectively. It was demonstrated that the k-value of cubic-HfO2 was ~30 in doped case, while ~50 in dynamic PDA case. A kinetic analysis of the recovery process from cubic to monoclinic phase in the dynamic PDA HfO2 was performed according to the Johnson-Mehl-Avrami law.
(Invited) XPS Study on Chemical Bonding States of high-κ/high-μ Gate Stacks for Advanced CMOS
Authors: Nohira Hiroshi , Komatsu Arata , Yamashita Koji , Kakushima Kuniyuki , Iwai Hiroshi , Hoshi Yusuke , Sawano Kentarou , Shiraki Yasuhiro
Published: October 2011

The paper reviews the two topics on the non-destructive characterization of high-k/high-mobility gate stacks using the hard X-ray(7.94 keV) photoemission spectroscopy. The first topic is the change in the compositional depth profiles and the chemical bonding states of HfO2/Si-cap/strained-Ge/Si0.5Ge0.5/Si(100) laminating structures. The second topic is the influence of HF, (NH4)2S and HMDS treatments on In0.53Ga0.47As surface, La2O3 interlayer insertion on the chemical bonding states at high-k/In0.53Ga0.47As interface. Analyses of Ge 2p, Si 1s and Hf 3d spectra show that the strained-Ge layer is oxidized during the deposition of HfO2 in the case of 1-nm-thick Si cap layer and that strained-Ge layer is not oxidized in the case of 3 and 5-nm-thick Si cap layer. A critical Si thickness is also extracted. Analyses of measured spectra show that the oxidation of In0.53Ga0.47As is suppressed by La2O3 interlayer insertion ant that (NH4)2S treatment can suppress the oxidation of In0.53Ga0.47As surface.