bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Interface Trap Density in Advanced SOI MOSFETs
Authors: Bawedin Maryline , Cristoloveanu Sorin , Chang Sungjae , Valenza Matteo , Martinez Frederic , Lee Jonghyun
Published: April 2011

The density of traps at the top interface is difficult to assess in advanced SOI MOSFETs with high-K dielectric and ultrathin film. Searching for a characterization strategy, we compare various approaches: front-channel subthreshold slope, back-channel slope, and coupling coefficient between the front and back channels. The back-channel slope shows the largest variation with the front trap density. However, the resolution may not be sufficient for MOSFETs with very thin buried oxide.
Single Crystal Silicon Thin Film on Polymer Substrate by Double Layer Transfer Method
Authors: Senawiratne Jayantha , Usenko Alex
Published: April 2011

We report discovery of new method to transfer a single crystal silicon thin film onto a bendable polymer substrate by using layer transfer process. The method includes creation of mechanically weakened layer 100 nm - 600 nm below the Si wafer surface using boron and hydrogen ion implantations. Silicon mother wafer is then pre-bonded to glass and exfoliated. Exfoliation divides the glass-silicon assembly into weakly bound Si thin film on glass and leftover mother Si wafer. Then the silicon thin film was transferred from glass substrate into a polymer substrate.
Zero Temperature Coefficient of Current Gain Cutoff Frequency and Maximum Oscillation Frequency for Various SOI and Si Bulk MOSFETs
Authors: Emam Mostafa , Vahoenacker-Janvier Danielle , Raskin Jean-Pierre
Published: April 2011

A Zero Temperature Coefficient characteristic is presented and characterized for the first time for current gain cutoff frequency and maximum oscillation frequency of different MOSFET structures. The benefits of these points on the design of RF circuits are of first importance especially for harsh environment applications and high density RF circuits.
Global and/or Local Strain Influence on p- and n MuGFET Analog Performance
Authors: Agopian Paula G. , Martino Joao A. , Simoen Eddy , Claeys Cor
Published: April 2011

In this work, the analog performance is evaluated for tri-gate p- and nMuGFETs processed with and without the implementation of different global or local strain engineering techniques. For n-channel devices, the intrinsic voltage gain showed to be worse for strained devices when the fin is narrow. Only for wider fins the voltage gain increases with the strain efficiency due to mobility enhancement. Besides the voltage gain, the transconductance, output conductance and Early Voltage are also evaluated. In spite of the smaller impact of strain engineering, radiated pMuGFETs show better analog behavior for all studied parameters.
Fin Pitch Impact on Biaxial/Uniaxial Strain Engineering of Triple-Gate Devices
Authors: Rodrigues Michele , Sonnenberg Victor , Martino Joao A. , Collaert Nadine , Simoen Eddy , Claeys Cor
Published: April 2011

This work characterizes the analog performance of SOI n-MuGFETs with uniaxial and biaxial strain configuration with respect to the influence of the fin pitch distance. Improved intrinsic gain can be achieved on strained devices independent of the pitch, mainly due to the increased transconductance. Larger fin pitch in the uniaxial strain case showed a higher gain. However, for the biaxial devices the smaller pitch resulted in a larger gain thanks to the increased Early voltage.
An Analytical Model for the Non-Linearity of Triple Gate SOI MOSFETs
Authors: Doria Rodrigo T. , Martino Joao A. , Simoen Eddy , Claeys Cor , Pavanello Marcelo A.
Published: April 2011

This work proposes a physically-based analytical model for the non-linearity of Triple-Gate MOSFETs. The model describes the second order harmonic distortion (HD2), usually the major non-linearity source, as a function of the device dimensions, the series resistance, the low field mobility and the mobility degradation factor (θ). The model was applied to transistors of different channel lengths and fin widths and allowed to conclude that θ is the parameter which most contributes for the increase of HD2. The model was validated for both unstrained and strained FinFETs.
New Capacitorless Dynamic Memory Compatible with SOI and Bulk CMOS
Authors: Rodriguez Noel , Gamiz F. , Cristoloveanu Sorin
Published: April 2011

We introduce a capacitorless DRAM cell based on a multibody transistor concept. The device features a body partitioning with dedicated regions for hole storage and electron current sensing. This separation allows aggressive scaling beyond the limits imposed by the supercoupling effect. The cell is fully compatible with both standard bulk and Silicon On Insulator substrates without changes in its architecture. Numerical simulations demonstrate its performances in terms of 1T-DRAM operation, current margins and retention time.
Radiation-Induced Pulse Noise in SOI CMOS Logic
Authors: Kobayashi Daisuke , Hirose Kazuyuki , Ikeda Hirokazu , Saito Hirobumi
Published: April 2011

A comprehensive study on radiation-induced pulse noises in SOI CMOS logic is reviewed. The noise pulses are called single event transients or SETs and becoming a serious source of soft errors in logic systems. As a result of miniaturization of transistors, concern about the soft error problems caused by the SETs are growing not only in special applications for harsh radiation environments like space but also in usual ones used on the ground. It is important to reveal what the SET is in its nature. Measurement techniques and analytical model have been developed for the purpose.They are introduced together with experimental data obtained with test circuits fabricated by a commercial 0.2-micrometer fully-depleted SOI technology. Issues to be solved for use of SOI technologies in realizing radiation hardened devices are also described with a practical example, or a development process of radiation hardened SOI SRAMs.
A Tunable Color Filter Using Sub-Micron Grating Integrated with Electrostatic Actuator Mechanism
Authors: Miyao Hajime , Takahashi Kazuhiro , Ishida Makoto , Sawada Kazuaki
Published: April 2011

We propose a NEMS (Nano Electro Mechanical Systems) tunable color filter using sub-micron grating, which can modulate the reflected light by changing the period of the sub-micron grating pixel by means of electrostatic actuation. The NEMS electrostatic actuator could be designed a high mechanical resonance frequency with a relatively low drive voltage. The sub-micron grating was made in a top layer of an SOI (Silicon on Insulator) wafer. The tiny anchors were covered by parylene N during the sacrificial release process using buffered hydrofluoric acid. The color tuning from yellow to green was demonstrated at 20 V operation.
Nanomechanical Testing of Free-Standing Monocrystalline Silicon Beams
Authors: Bhaskar Umesh K. , Houri Samer , Passi Vikram , Pardoen Thomas , Raskin Jean-Pierre
Published: April 2011

A fabrication process to characterize single crystalline silicon microbeams under uniaxial tensile stress is presented. The microbeams subjected to uniaxial tensile strain are successfully released without any stiction by the use of critical point drying tool. Based on the deformation measured using scanning electron microscope (static measurement) images, the corresponding strain and stress are calculated to plot the uniaxial tensile characteristics curve of monocrystalline silicon. Dynamic stress determination based on the measurements of flexural resonance frequency of the released beams is discussed. Finally, comparison of stress values obtained using the two methods is shown.
X-ray Radiation Effects in Circular-Gate Transistors
Authors: Cirne Klaus H. , Silveira Marcilei , De Lima Jader A. , Seixas Luis E. , Gimenez Salvador P.
Published: April 2011

This work performs two experimental comparative studies of the x-ray radiation effects in the Conventional, Wave and Overlapping-Circular-Gate MOSFETs. The first one studies the x-ray radiation influence where the devices are not biased during the x-ray radiation process for two channel lengths and after they are exposure to a x-ray radiation of 1.5 Grad with a dose ratio of the 22 Mrad/min. The second study performs an experimental comparative study of the x-ray influence between the Conventional and Overlapping-Circular Gate MOSFET for a channel length equal to 12 µm, when they are submitted to the x-ray irradiation of 60 Mrad and maintaining the same bias conditions (overdrive gate and drain voltages) during the irradiation process. In both studies, we observe that the Overlaping-Circular Gate transistor present higher x-ray irradiation robustness than those found in the other transistors due to the absence of the bird beak in this structure.
Numerical Modeling of Noise and Transport in SOI Devices
Authors: Meinerzhagen Bernd , Pham Ahn-Tuan , Hong Sung-Min , Jungemann Christoph
Published: April 2011

Accurate numerical modeling for SOI devices of technical interest has always been challenging concerning the accuracy of the physical models as well as concerning the convergence properties of the numerical algorithms. For partially depleted devices the most important underlying reason is the necessity of a precise modeling of low impact ionization and diffusion currents in order to get reasonable results for the kink effect and noise. On the other hand in fully depleted devices the DIBL effect at smaller channel lengths can only be sufficiently suppressed using thin Silicon films. Therefore a precise modeling of size quantization based on the Schrödinger Equation is typically needed for fully depleted devices. Today even more challenges exist due to the application of strain, hetero junctions and non standard interface and channel orientations. In this paper it is demonstrated that most of these challenges can be adequately addressed today.
Functionalization of Silicon Nanowires for Specific Sensing
Authors: Passi Vikram , Dubois Emmanuel , Celle Caroline , Clavaguera Simon , Simonato Jean Pierre , Raskin Jean-Pierre
Published: April 2011

Thanks to their large surface-to-volume ratio, silicon nanowires (Si NWs) are extremely sensitive to all phenomena which could alter their surface potential and charge distribution. Those surface variations lead to a change of the Si NWs equivalent conductance. The use of the output conductance of a silicon nanowire as a compact transducer for direct detection of (bio)chemical molecules or gases has gained immense attention these last years. In this paper, fabrication of silicon nanowires using top-down approach is shown, with simple calculations to determine hole mobility, hole concentration and resistivity. Transfer characteristics and sampling measurements were performed on the nanowires with and without surface functionalization under various ambient conditions indicating the importance of functionalization in order to avoid any environment effect on the transport properties of the nanowires.
Performance of Ultra-Low-Power SOI CMOS Diodes Operating at Low Temperatures
Authors: De Souza Michelly , Rue Bertrand , Flandre Denis , Pavanello Marcelo A.
Published: April 2011

In this work the low temperature performance of ultra-low-power SOI CMOS diodes is presented. Experimental measurements performed in fabricated devices from 148K to 373K show that the temperature lowering can promote a significant leakage current reduction and increase of the forward current. Two-dimensional numerical simulations are used to extend the studied temperature range and analyze the doping concentration influence on the low temperature operation of these diodes.
Ultra-Thin GaN Membranes Fabricated by Using Surface Charge Lithography
Authors: Tiginyanu Ion , Popa Veaceslav , Stevens-Kalceff Marion A.
Published: April 2011

We report on fabrication of ultra-thin GaN membranes of nanometer scale thickness, by using the concept of surface charge lithography based on low-energy ion treatment of the sample surface with subsequent photoelectrochemical etching. The membranes prove to be transparent to both electrons and UV radiation, emit mainly yellow cathodoluminescence, and exhibit electrical conductivity. Successful fabrication of nanometer-thin membranes opens unique possibilities for exploration of two dimensional GaN-based structures predicted to be ferromagnetic with defect-induced half-metallic configuration which is of peculiar importance for spintronics applications.
(Invited) Experimental Evidence that the Plasma-Assisted MBE Growth of Nitride Alloys is a Liquid Phase Epitaxy Process
Authors: Moustakas Theodore D. , Bhattacharyya Anirban
Published: April 2011

In this paper we propose that under Ga-rich conditions the growth of III-Nitride semiconductors by plasma-assisted MBE takes place though saturation of the metallic Ga covering the surface of the growing film with nitrogen, alloy constituents and impurities. According to this model the growth process is a liquid phase epitaxy (LPE) rather than vapor phase epitaxy. Experimental evidence is presented in support of this model. Such include, for example, that the growth rate of GaN does not decrease at temperatures in excess to 800 ºC, a result attributed to higher solubility of active nitrogen in Ga at higher temperatures. Also the metallic Ga in the surface of the film controls the incorporation of impurities and is responsible for the introduction of compositional inhomogeneities and thus band structure potential fluctuations in AlGaN due to lateral statistical fluctuations of the thickness of Ga in the surface.
Effect of Growth Parameters on Stress in HVPE GaN Films
Authors: Tsyuk Alexander , Gorbunov Ruslan , Voronenkov Vladislav , Lelikov Yuriy , Latyshev Philippe , Zubrilov Andrey , Rebane Yuriy , Bochkareva Natalia , Shreter Yuriy
Published: April 2011

The effect of growth parameters on stress in thick GaN films grown on sapphire by HVPE method was investigated. We have found two modes of growth with different growth stress. Films grown in one mode have rough surfaces and low stress. The second mode leads to smooth surfaces but the films contain many cracks due to high growth stress. A combination of these modes allows growth of films without cracks and with smooth surfaces.
Microstructure Characterization of Cu-Alloyed GaN Grown by Plasma Assisted Molecular Beam Epitaxy
Authors: Huang Teng-Hsing , Ganz Philipp R. , Chang Liuwen , Schaadt Daniel M. , Bao Jhong-Sing
Published: April 2011

Cu-alloyed GaN epilayers were prepared by plasma assisted molecular beam epitaxy with Cu-to-Ga beam equivalent pressure ratio of 1.2 to 4.8 %. Islands enriched with Cu were found on the GaN epitaxial layers grown in a Ga-rich environment. The islands are composed of a Cu9Ga4 intermetallic phase and GaN between which an orientation relationship was identified as [111]Cu9Ga4//[1 10]GaN and (10)Cu9Ga4//(0001)GaN. X-ray spectroscopy analyses indicated that the 1.2 % and 4.8 % samples contains 0.10 0.02 wt.%Cu and 0.04 0.03 wt.%Cu, respectively.
3C-SiC Film Growth on Si Substrates
Authors: Severino Andrea , Locke Christopher , Anzalone Ruggero , Camarda Massimo , Piluso Nicolò , La Magna Antonino , Saddow Stephen , Abbondanza Giuseppe , D'Arrigo Giuseppe , La Via Francesco
Published: April 2011

The aim of this work is to give an overview on 3C-SiC growth on Si substrates. Starting from the reasons why SiC is considered such an interesting innovative material, with a survey of application already demonstrated, we will present data explaining the most important issues in this hetero-epitaxy system and how the chemical vapor deposition process influences the resulting 3C-SiC film properties. 3C-SiC crystal structure is strongly dependent on the process parameters within the reaction chamber during growth as well as the substrate surface properties. Part of this work is then focused on the main crystallographic defects characterizing the 3C-SiC/Si system and on the resulting wafer bow due to the large misfit between the materials. Defects and wafer bow, are a direct consequence of the large stress generated at the interface. The work closes discussing the encouraging improvements in 3C-SiC crystal quality obtained by the introduction of compliant Si substrates.
High Power Density UV Optical Stress for Quality Evaluation of 4H-SiC Epitaxial Layers
Authors: Canino Andrea , Camarda Massimo , La Via Francesco
Published: April 2011

An application of an optical characterization technique able to evaluate the quality of 4H-SiC epitaxial layers is here proposed. By using high power density UV optical pumping it was possible to stress 4H-SiC epitaxial layers after the CVD growth process and verify the generation and evolution of Single Shockley faults across the interface through the epitaxial layer without the fabrication of bipolar junctions. Thanks to this characterization method, it is possible to choose a good CVD process for the growth of epitaxial layers.
Influence of Doping and Co-Doping on the Behavior of Sputtered ZnO Thin Films
Authors: Shtereva Krasimira S. , Sutta Pavol , Pecz Bela , Novotny Ivan , Kovac Jaroslav , Tvarozek Vladimir
Published: April 2011

A co-dopand approach was used to investigate influence of gallium-nitrogen co-doping on the microstructure and electrical parameters of ZnO. ZnO:Ga:N thin films were deposited by rf diode sputtering at varying nitrogen content (0÷100%) in Ar/N2 gas. ZnO:Ga films (0% N2) showed minimum resistivity of 0.12 Ωcm, electron concentration of 2.5x1019 cm-3 and mobility of 2 cm2/Vs. A hole concentration of 2.6x1018 cm-3, a mobility of 2 cm2/Vs and a resistivity of 1.5 Ωcm in ZnO:Ga:N resulted from the deposition with 100% N2 in Ar/N2 gas. XRD patterns revealed a profound impact of Ga-N co-doping on film orientation. The estimated crystallite size varied from 234 to 41 nm, depending on the N2 content. TEM images of the co-doped films along with the corresponding selected area diffraction pattern indicated a polycrystalline, columnar layer with a c-axis preferred orientation. AFM images demonstrated the different crystalline structure and grain formation depending on nitrogen content.
Role of Zn-Interstitial Defect in the Ultraviolet Emission from ZnO
Authors: Hashmi Muhammad Asghar , Mahmood K , Ali A , Hasan M , Raja M , Hussain I , Willander Magnus
Published: April 2011

ZnO layers having variable percentage of Zn-contents were prepared to ascertain the role of Zn-interstitial defect in the ultraviolet (UV) emission from ZnO with the help of photoluminescence (PL) measurements. The typical PL spectrum performed at room temperature displayed a dominant UV line at 3.28 eV and a visible line centered at 2.25 eV. A detailed investigation reveals that the UV emission is due to bound exciton transition-Zn-interstitial transition. The UV intensity due to Zn-rich sample was almost double as compared to that of the sample with lower Zn-contents. The results obtained from the energy dispersive x-ray spectrum (EDAX) and Raman spectroscopy strengthened the PL results.
Nitrided Gate Oxide Formed by Rapid Thermal Processing for 4H-SiC MOSFETs
Authors: Constant Aurore , Godignon Philippe , Montserrat Josep , Millán Jose
Published: April 2011

Rapid Thermal Processing has been evaluated as an alternative to the conventional furnace process for gate oxide formation of SiC MOSFETs. We show that the growth of the SiO2 films in a RTP chamber is orders of magnitude faster than in a conventional furnace. As well as being fast, this innovative oxidation method produces a significant improvement of MOSFET performances. Indeed, we demonstrate that combining the beneficial effect of in-situ surface preparation by H2 anneal with the one of N2O oxidation, the channel mobility increases and the electrical stability with respect to constant bias stress at low-field is improved.
Two-State Current Conduction in High-k/SiO2 Stacked Dielectric with High Bandgap 4H-SiC Substrate
Authors: Chiang Jung-Chin , Hwu Jenn-Gwo
Published: April 2011

In the high-k/SiO2 stacked dielectric MOS capacitor, the electrons captured by the defects associated with the oxygen vacancies in the dielectric may affect the trap assist tunneling current of the device. In this work, high bandgap material was utilized as substrate for its considerable interface states which are important to enhance the effect of trapped charges on the tunneling current. It was found that the electrons captured in high-k/SiO2 interface layer were crucial to block the current conduction path. Two-state current behavior was clearly observed by this mechanism.
Effects of SiO2 Passivation on Oxygen Annealed AlGaN/GaN HEMTs
Authors: Seok Ogyun , Kim Young-Shil , Ha Min-Woo , Han Min-Koo
Published: April 2011

We have investigated the effects of SiO2 passivation on the oxygen annealed AlGaN/GaN HEMTs. DC and pulsed I-V characteristics are analyzed to investigate the variation of trap level caused by SiO2 passivation and oxygen annealing. Both of oxygen annealing and SiO2 passivation are found to be effective methods to suppress the surface leakage current and increase the breakdown voltage of the AlGaN/GaN HEMTs. After an oxygen annealing, the leakage current is decreased from 621 μA/mm to 1.7 nA/mm when -5 V of VGS and -50 V of VDS are applied. However, the leakage current is increased to 5.7 μA/mm after SiO2 passivation on the oxygen annealed AlGaN/GaN HEMTs. The electron trapping through the deep trap is found to be dominant mechanism of the suppressed leakage current of the AlGaN/GaN HEMTs due to the low probability of the de-trapping from the deep trap to conduction band. SiO2 passivation suppresses the electron trapping through deep trap, which is produced by oxygen annealing. The breakdown voltage of conventional device without any treatment is 180 V. After oxygen annealing, the breakdown voltage is increased to 830 V while the AlGaN/GaN HEMT employing both of SiO2 passivation and oxygen annealing is 650 V.
The Effect of Different Carrier Gases and Channel Thicknesses on the Characteristics of ZnO TFTs Prepared by Atmospheric Pressure Plasma Jet
Authors: Chang Kow-Ming , Huang Sung-Hung , Chi Chia-Wei , Wu Chin-Jyi , Lin Je-Wei , Chang Chia-Chiang
Published: April 2011

Thin film transistors (TFTs) with a ZnO channel layer deposited by atmospheric pressure plasma jet (APPJ) were demonstrated. ZnO channel layers were fabricated with a non-vacuum and low-temperature process (100°). The effects of different carrier gases (nitrogen gas and compressed dry air) and channel thickness on the characteristics of ZnO TFTs were investigated. Reactive oxygen species can effectively repair the oxygen vacancies result in a low leakage current. By reducing the channel thickness, the undesired source to drain current flow can be eliminated. By using CDA as a carrier gas and reducing the channel thickness, a subthreshold swing of 3.75 V/decade, a field-effect mobility of 3.49 cm2/Vs and a Ion/Ioff current ratio of 4.08×107 were obtained
Top-Down Processed SOI Nanowire Devices for Biomedical Applications
Authors: Ingebrandt Sven , Vu Xuan-Thang , Eschermann Jan Felix , Stockmann Regina , Offenhausser Andreas
Published: April 2011

We present silicon nanowire (SiNW) devices, which were fabricated in a top-down process from silicon-on-insulator (SOI) substrates with a high yield. Electronic characterization proved reliable electronic properties. Here we report the versatile use of the devices in different applications like label-free sensing of DNA hybridization, electronic detection of cellular signals, and detection of proteins. Compared to micro-sized devices, the SiNWs show an improved sensitivity. Analyses of the electronic cell-nanowire contact showed that the important seal resistance is largely increased, which is a prerequisite for highly-sensitive detection of cellular activity. In all applications the SiNW devices show a reliable performance and are highly interesting for future biomedical products.
Electrochemical Characterization of Regularly-Aligned Nanopore Array Membranes Filled with Electrolyte Solutions and Their Use for Detection of Nucleic Acid Hybridization
Authors: Ellis Jonathan S. , Herzog Gregoire , Glynn Barry , Arrigan Damien
Published: April 2011

We report on the electrochemical characterization of regularly-aligned cylindrical nanopore arrays supported in silicon nitride membranes and preliminary results for the detection of nucleic acid hybridization on the nanopore walls. A range of nanopore arrays with diameters between 30 and 150 nm were examined. We tested the effect of pore diameter, number of pores, electrolyte concentration and surface chemistry on the conductance of the nanopore membranes. The pores were functionalized with single-stranded DNA and conductance measurements were performed before and after hybridization. In many cases, changes in current rectification were observed following hybridization, which is discussed as a strategy for nucleic acid hybridization and interactions.
Fully Integrated Immunoassays on a Disc
Authors: Cho Yoon-Kyoung , Kim Tae-Hyeong , Park Jiwoong , Hwang Hyundoo , Sunkara Vijaya , Lee Beom Seok , Kim Jintae , Kim Hanshin
Published: April 2011

We report a fully automated "lab-on-a-disc" system for multiplex immunoassay starting from real samples such as whole blood or saliva. While immunoassay has been a standard tool in identification of protein biomarkers in clinical diagnostics, the tests can be labor intensive and time consuming. Integration with microfluidic technology allows more precise control of fluids while also reducing the expensive reagent consumption, the required analysis time and possible manual errors. In this paper, a lab-on-a-disc for multiplex immunoassay is introduced in addition to the recently reported fully integrated bead-based immunoassay on a disc (1) and simultaneous analysis of biochemistry and immunoassay on a disc (2).
Glucose Specific GDH-PQQ based Sensor Strip: Application of Engineered GDH-PQQ Harboring a de novo Designed Loop Region
Authors: Nagae Daichi , Nakajima Mitsuharu , Ferri Stefano , Sode Koji
Published: April 2011

In response to an FDA Public Health Notification regarding the risk associated with the use of PQQGDH in glucose monitoring technology due to its broad substrate specificity, many manufacturers have switched to alternative enzymes. We present the challenges in the biomolecular engineering of PQQGDH and our achievement in the construction of an enzyme that is highly specific toward glucose. We designed a loop region that appears to sterically prevent the binding of disaccharides, such as maltose, into the substrate binding cavity. Combination of the designed loop region with previously generated mutations that were found to improve substrate specificity yielded enzymes that are virtually non-active toward maltose, while retaining sufficient activity toward glucose. A screen-printed carbon electrode employing thus developed engineered PQQGDH was capable of determining glucose concentrations with 0.5 µl sample within 5 seconds while barely responding to maltose. Our strategy and achievements are expected to overcome the enzyme's "maltose problems".
Relation between Effective Charge Numbers and Signals Caused by Protein Adsorption on Field Effect Transistor Detection
Authors: Hideshima Sho , Nakamura Takahiro , Kuroiwa Shigeki , Osaka Tetsuya
Published: April 2011

This paper describes a practical method for predicting signals of an adsorbed protein detected by field effect transistors (FETs). The FETs detect the change of the surface charge caused by protein adsorption. The sensing signals strongly depend on an ionic strength of the buffer solution. The prediction of signals is useful for optimizing the strength. A calculation method using three-dimensional conformation structure of proteins was proposed for the prediction tool in the latest paper citing biotin-avidin interaction as an example. To verify availability of the method for alternative adsorbed protein, an adsorption model of streptavidin, which also has a binding ability to biotin, was investigated. Streptavidin has little charge in a buffer solution at pH 7.4 calculated from the method. The results suggest that the signals caused by adsorption of streptavidin were barely detectable using a biotinylated FET.
Electrochemically Controlled Separation of DNA Oligomers with High Surface Area Conducting Paper Electrode
Authors: Razaq Aamir , Stro̸mme Maria , Nyholm Leif , Mihranyan Albert
Published: April 2011

In order to obtain an efficient electrode material with large ion-exchange capacity, we chemically polymerized a thin (~30-50 nm) PPy layer on a high surface area Cladophora sp. algae cellulose substrate. The resulting composite had the appearance of a black flexible paper sheet with good mechanical strength, large specific surface area (80 m2/g), and high electron conductivity (~2 S/cm). The latter material was previously utilized as an electrode material for efficient (and fully reversible) separation of inorganic (chloride and nitrate) and organic (p-toluenesulfonate) anions. The oxidation of these PPy conducting paper electrodes also resulted in the inclusion of single stranded d(T)6 hexamers as a counter ion into the film even in the presence of large amounts of other competitor anions. In this study carbon chopped fibers (CCF) were incorporated with the PPy-cellulose nano fibers to improve the reversibility of the electrochemically controlled DNA separation. The addition of CCF into above material increased the electron transfer mechanism among the PPy sites during reduction state. The outcome of the above-described investigations showed a partial reversibility of the electrochemically-controlled DNA extraction accounting to ~45% recovery from the extracted amount. The PPy composite paper electrode material can thus serve as a new technology platform for developing electrochemically-controlled separation techniques in biotechnology, nanoanalytical systems, paper-based diagnostic devices, and immunosensors.
Exploring Tissue Response to Field Mediated Plasmid Delivery
Authors: Gilbert Richard , Llewellyn J. Anthony , Schoenbach Karl H. , Heller Loree , Hoff Andrew
Published: April 2011

A non-viral treatment protocol for melanoma requires that the therapeutic agent be reliably delivered at the tissue target followed by an appropriate tumor destructive response. Electric field mediated drug delivery or plasmid delivery have been clinically demonstrated as successful treatment protocols for primary tumors and metastatic disease, respectively. However, in both treatment protocols, the challenge to develop a method and appropriate instrument system to predict the therapeutic impact of a given protocol on the target tumor still remains. Evidence developed by this research team strongly suggests that impedance spectroscopy may provide a basis for a rapid in-vivo monitor that will allow the treating physician to assess the potential of successful protein expression for a specific patient at the time of treatment.
Terahertz Chemical Imaging of Molecular Networks for Pharmaceutical Applications
Authors: Ajito Katsuhiro , Ueno Yuko , Song Ho-Jin , Tamechika Emi , Kukutsu Naoya
Published: April 2011

A terahertz (THz) chemical imaging system was fabricated for the detection of two-dimensional molecular networks in pharmaceutical tablets. Frequency-dependent THz images of homemade tablets containing polymorphic forms enables us to determine the distribution of two polymorphic forms. The system also provided THz images of polymorphic form distribution of famotidine in an over-the-counter drug tablet for the first time. Furthermore, the molecular mechanics method was used to determine the vibrational modes of famotidine polymorphic forms.
Surface Charge Density Driven Delivery of Drugs and Plasmid DNA to Skin Using Atmospheric Ion Sources
Authors: Hoff Andrew , Connolly Richard , Ramachandran Niraj , Jaroszeski Mark
Published: April 2011

Low energy ion deposition to create electric fields in tissue provides an attractive means to electrically mediate and induce delivery of normally non-permeant molecules to tissue cells in vivo. Electrically mediated therapies have progressed to clinical demonstration yet require anesthetic to minimize patient discomfort. Ions generated at atmospheric pressure may be applied to the skin surface to produce an electric field in the tissue leading to an effective delivery of molecules to cells. Such processes are charge limited and therefore do not produce high current in the tissue.
Process Engineering and Trap Distribution for Dielectric/Si Interfacial Layer in High-k Gated MOS Devices
Authors: Chang-Liao Kuei-Shu , Fu Chung-Hao , Lu Chun-Chang , Chang Yu-An , Hsu Ya-Yin , Tsao Che-Hao , Wang Tien-Ko , Heh Da-Wei , Li Y.C. , Tsai Wen-Fa , Ai Chi-Fong , Hou Fu-Chung , Hsu Yao-Tung
Published: April 2011

The effects of interfacial layer at high-k dielectric/Si substrate formed by using stress-relieved pre-oxide (SRPO) treatment on electrical characteristics of MOS devices were studied in this work. The equivalent oxide thickness value could be scaled with reducing the thickness of the high quality IL. The reliability in terms of stress-induced leakage and stress-induced Vfb shift is clearly improved for MOS device with a SRPO treatment. Besides, the constant-voltage stress-induced interface trap generation in MOSFET was measured by charge-pumping techniques. The influences of stress and recovery on devices with HfO2 high-k dielectric are also compared. Results show that the stress induced Vth shifts can be separated into two stages, namely, trap filling and generation. The trap generation stage is only determined by the stress voltage and temperature.
Current Understanding of the Transport Behavior of Hydrogen Species in MOS Stacks and Their Relation to Reliability Degradation
Authors: Liu Ziyuan , Fujieda Shinji , Ishigaki Hirokazu , Wilde Markus , Fukutani Katsuyuki
Published: April 2011

We review recent experiments that suggest a comprehensive model for the reversible hydrogen (H) transport between the poly-Si interface and the oxide/Si interface of MOS stacks. The H diffusion in intact model MOS structures is probed by H depth profiling via resonant 15N-H nuclear reaction analysis (NRA). It is demonstrated that MOS device degradation correlates with H accumulation in the oxide/Si interface region. A specific ultra-thin oxynitride is discovered in the poly-Si/oxynitride interface as well as in the near-surface region of N2-annealed nitride films and shown to function as a potential H-storage layer. The interfacial storage layer between the poly-Si gate and the oxynitride dielectric of MOS transistors is found to contain two kinds of H species, which are mobile and stable, respectively, versus irradiation-induced relocation. The mobile H, if stimulated by energetic carriers, migrates across the gate films and relocates to the SiO2/Si interface, causing device instabilities. Understanding this basic hydrogen transport behavior allows conceiving fabrication countermeasures to improve the device reliability.
Detailed Analysis of Si-SiO2 Interface Traps in State-of-the-Art MOSFETs Using Charge Pumping
Authors: Bauza Daniel
Published: April 2011

Based on charge pumping (CP) mechanisms, the way Si-SiO2 interface traps interact with the gate CP signal in state-of-the-art MOSFETs with a thick SiO2 gate dielectric is detailed. The consequences that can be deduced or studied from the previous results are presented. This includes the way the interface is probed, the slope of the CP curves and the resulting interface trap density extraction from them. The dependence of CP curves with gate signal frequency and the high frequency limit case are dealt with using simulation. Both are very well accounted for, providing new information on Si-SiO2 interface trap characteristics.
Clear Difference between the Chemical Structure of SiO2/Si Interfaces Formed Using Oxygen Radicals versus Oxygen Molecules
Authors: Suwa Tomoyuki , Kumagai Yuki , Teramoto Akinobu , Muro Takayuki , Kinoshita Toyohiko , Ohmi Tadahiro , Hattori Takeo
Published: April 2011

Soft-x-ray-excited angle-resolved photoelectron spectroscopy studies on silicon dioxide films formed using oxygen radicals (OR) versus oxygen molecules (OM) are reported. Most of intermediate oxidation states of Si, so called suboxides, consisting of Si3+, Si2+, and Si1+ are localized at and near the SiO2/Si interfaces. The suboxides formed utilizing OM are located extremely close to the interfaces, while suboxides formed utilizing OR are located not only at the interface but also in the Si substrate. This implies the penetration of a part of OR into the Si substrate to form Si1+ and to relax the interfacial stress. Intermediate chemical bonding states of Si are formed in Si substrate closer to the interface as compared with those formed utilizing OM. This implies that the interfacial stress in the former is smaller than that in the latter.
Essential aspects of Negative Bias Temperature Instability (NBTI)
Authors: Islam Ahmad E. , Mahapatra Souvik , Deora Shweta , Maheta Vrajesh D. , Alam Muhammad Ashraful
Published: April 2011

We develop a comprehensive theoretical framework for explaining the key and characteristic experimental signatures of NBTI. The framework is based on an uncorrelated dynamics of interface-defect creation/annihilation described by Reaction-Diffusion (R-D) theory and hole trapping/detrapping into/out-of oxide defects based on a generalized Shockley-Read-Hall model. The proposed theory can consistently explain the long-term stress-phase power-law time exponent, stress/relaxation-phase temperature dependence, characteristic feature of duty-cycle dependence, and universal feature of frequency independence - measured in DC and AC stress conditions over a wide variety of transistors. Thus, we confirm the general validity of R-D theory in explaining the universal features (irrespective of dielectric material) of both DC and AC NBTI. The non-universal features of NBTI have correlation with the amount of oxide-defects within the dielectric and do not affect AC NBTI measurements at lower duty cycle. Decomposition of these (uncorrelated) universal and non-universal components is, therefore, essential before comparison with any theory.
Atomic Imaging of Atomic H Cleaning of InGAs and InP for ALD
Authors: Melitz Wilhelm , Shen Jian , Kent Tyler , Droopad Ravi , Hurley Paul , Kummel Andrew C.
Published: April 2011

Air exposed III-V surfaces nearly always have electronic defects which prevent full modulation of the Fermi level thereby impeding their use in practical semiconductor devices such as metal oxide field effect transistors (MOSFETs). For a high speed device, the air induced defects and contaminants need to be removed to reduce trap states while maintaining an atomically flat surface to minimize interface scattering thereby maintaining a high carrier mobility. Using in-situ atomic scaling imaging with scanning tunneling microscopy, a combination of atomic hydrogen dosing, annealing and trimethyl aluminum dosing is observed to produce an ordered passivation layer on air exposed InGaAs(001)-(4×2) surface with only monatomic steps.
Surface Passivation of InGaAs/InP HBTs Using Atomic Layer Deposited Al2O3
Authors: Driad Rachid , Benkhelifa Fouad , Kirste Lutz , Lösch Rainer , Mikulla Michael , Ambacher Oliver
Published: April 2011

In this contribution, we investigate the Al2O3 surface passivation of InGaAs/InP heterostructures using thermal atomic layer deposition (ALD) with water vapor, and plasma ALD with oxygen plasma. The microstructure and optical properties of the Al2O3 layers are examined by X-ray reflectivity (XRR) and spectroscopic ellipsometry (SE) on InGaAs/InP epilayers and Si substrates. The dc current gain and breakdown voltage of InGaAs/InP heterostructure bipolar transistors (HBTs) have subsequently been used to evaluate the impact and efficiency of the ALD-Al2O3 passivation layers. The thermal-ALD-Al2O3 passivated InGaAs/InP HBTs show relatively higher current gains as compared to structures passivated using the plasma-ALD process, suggesting differences in the dielectric-semiconductor interface properties. The common emitter characteristics of both (thermal and plasma) ALD-Al2O3 passivated HBTs show, however, fairly comparable device breakdown voltages. These results will be contrasted with results from similar samples passivated with SiO2 using conventional plasma enhanced chemical vapor deposition (PECVD).
Optical and Electrical Properties of Si-Based Multilayer Structures for Solar Cell Applications
Authors: Nalini R. Pratibha , Cardin Julien , Dey Kalpana R. , Portier Xavier , Dufour Christian , Gourbilleau Fabrice
Published: April 2011

Among the materials of interest in the fields of solar cells, silicon Rich silicon Oxide (SRSO) has proved convincing results. In order to benefit from the carrier confinement within the active material, a multilayered arrangement of SRSO alternated with an insulating matrix is preferred. SiO2 matrix has been used as a host matrix, but its limitations appear due to the poor electrical conductivity. Hence, SiNx has become an alternative choice for such matrices in the recent past. This work compares the structure and luminescence properties of SRSO/SiO2 and SRSO/SiNx multilayers and demonstrates the interest in replacing SiO2 sublayer by SiNx. Optical and electrical characterizations are made on these materials We eventually propose a promising type of multilayer structure with enhanced photoluminescence and electrical conductivity with a control over the thermal budget.
Context Dependence Effects in Si/SiON Based Advanced CMOS Devices
Authors: Olubuyide Oluwamuyiwa O.
Published: April 2011

Significant sources of mechanical stress have been deliberately added into the active silicon of CMOS devices to improve carrier mobility. These include Dual Stress nitride Liners (DSL) and embedded Silicon Germanium (eSiGe) in the source and drain regions of PMOS transistors. Moreover, as transistor dimensions have shrunk, unintentional sources of variation such as Shallow Trench Isolation (STI) mechanical stress and dopant redistribution due to proximity to STI boundary or the well implant boundary (WPE) have also increased the systematic transistor variability. This increased systematic variability has impacted the product yield and provided the impetus to include context dependence in SPICE models of transistor electrical performance. This paper outlines a rigorous approach to not only quantify the physical mechanisms and impact of context effects, but also how to model these effects on the electrical transistor performance and various strategies to mitigate the impact of these context dependencies on digital circuit performance.
Impact of Gate Dielectric Geometry on the Nanowire MOSFETs Performance and Scaling
Authors: Li Ming-Fu , Cao Wei , Huang Daming , Shen Chen , Cheng S Q , Yao C. J. , Yu Hong Yu
Published: April 2011

(1)A 2D tunneling model is developed to assess the tunneling reduction in cylindrical gate (CG) in nanowire (NW) MOSFETs with radius Rs, comparing with the planar double gate (PG-DG) transistor with Tsemi=2Rs and same dielectric thickness Tox. High-k gate dielectric is more effective to suppress the gate leakage in NW than in PG transistors, (2) the carrier quantization induced tunneling barrier reduction is larger in NW than in DG-PG transistors. The gate tunneling rate is finally determined by combining two effects of (1) and (2). Different results for Si, Ge, and InGaAs NWs are demonstrated, (3) comparing with PG transistor, the overdrive gate voltage in NW transistor can be reduced significantly. At the same time evolution of dielectric charge generation, the NW transistor lifetime can be greatly extended.
Electrical and Structural Properties of Ternary Rare-Earth Oxides on Si and Higher Mobility Substrates and their Integration as High-k Gate Dielectrics in MOSFET Devices
Authors: Lopes J. Marcelo , Durğun Özben Eylem , Schnee Michael , Luptak Roman , Nichau Alexander , Tiedemann Andreas , Yu Wenjie , Zhao Qing-Tai , Besmehn Astrid , Breuer Uwe , Luysberg Martina , Lenk St. , Schubert Jurgen , Mantl Siegfried
Published: April 2011

The continuous downscaling in metal-oxide-semiconductor field effect transistors is approaching fundamental limits. Allied to new device architectures, novel materials are needed in order to continue the evolution of complementary metal-oxide-semiconductor technologies. The combination of high dielectric constant (k) oxides with silicon and other semiconductors having a higher charge carrier mobility (ex.: germanium) is currently a fundamental technologic issue that requires extensive investigation on materials science. The search for high-k oxides (with k > 20) that can offer stable interfaces combined with a low density of electrically active defects is a topic of major interest. In this contribution, we will review some of our results on the structural and electrical properties of REScO3 (RE = La, Gd, Tb, Sm) and LaLuO3 amorphous films on Si as well as on high mobility substrates, showing their potential as high-k dielectrics for future CMOS applications.
Plasma Enhanced Atomic Layer Deposition of ZrO2: A Thermodynamic Approach
Authors: Blanquet Elisabeth , Monnier Denis , Nuta Ioana , Volpi Fabien , Doisneau Beatrice , Coindeau Stephane , Roy J. , Detlefs Blanka , Mi Y. , Zegenhagen Jorg , Martinet C. , Wyon C. , Gros-Jean Mickael
Published: April 2011

In the pursuit of smaller and faster devices manufacture, integration of new materials exhibiting a high dielectric permittivity is going on to replace silicon oxide SiO2 in Metal/Insulator/Metal (MIM) capacitors and in Dynamic Random Access Memory (DRAM). Among these materials, the zirconium oxide, ZrO2, in its highest dielectric permittivity phase (the high temperature tetragonal one) is investigated. Atomic Layer Deposition (ALD) of out-of-equilibrium ZrO2 thin films in 3D architectures is explored using various approaches: evaluation of the zirconium gaseous precursor, influence of operating conditions, thermal behavior of the deposited films. Thermodynamic models are used to better understand the film growth.
Investigation of Electron and Hole Charge Trapping in LaLuO3 Stack MOS Capacitor Using the 3-Pulse CV Technique
Authors: Sedghi Naser , Mitrovic Ivona , Lopes Joao , Schubert Jurgen , Hall Stephen
Published: April 2011

The three-pulse CV measurement technique has been used to study electron and hole charge trapping and de-trapping in SiO2/LaLuO3 gate stacks on p-type silicon substrate. Variation of flat-band voltage shift due to electron and hole trapping with charging time and pulse amplitude has been investigated. The pulsed CV measurements have been taken at various ramp rates and times to delineate the influence of interface states. The time constant of interface states responses estimated experimentally. The three-pulse CV measurements at different ramp rates are also used to evaluate the reliability of the measurement technique.
Inelastic Electron Tunneling Spectroscopy (IETS) Study of Ultra-Thin Gate Dielectrics for Advanced CMOS Technology
Authors: Ma T.P.
Published: April 2011

The Inelastic Electron Tunneling Spectroscopy (IETS) technique, which relies on tunneling current to probe the ultra-thin gate dielectric in a metal-insulator-semiconductor (MIS) sandwich, is a powerful technique to address materials issues related to reactions and intermixing at interfaces, as well as properties related to carrier mobility and reliability in an advanced CMOS gate stack, such as phonon modes, impurities, and charge traps, for structures that are difficult to accurately characterize by other techniques. The principle of operation, experimental considerations, and examples will be shown in this paper to illustrate the capabilities and limitations of the IETS technique.