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Articles 31 - 60 of 60
Full-Text Articles in Engineering
On The Nature Of Shunt Leakage In Amorphous Silicon P-I-N Solar Cells, Sourabh Dongaonkar, Karthik Y, Dapeng Wang, Michel Frei, Souvik Mahapatra, Muhammad Alam
On The Nature Of Shunt Leakage In Amorphous Silicon P-I-N Solar Cells, Sourabh Dongaonkar, Karthik Y, Dapeng Wang, Michel Frei, Souvik Mahapatra, Muhammad Alam
Sourabh Dongaonkar
In this letter, we investigate the nature of shunt leakage currents in large-area (on the order of square centimeters) thin-film a-Si:H p-i-n solar cells and show that it is characterized by following universal features: 1) voltage symmetry; 2) power-law voltage dependence; and 3) weak temperature dependence. The voltage symmetry offers a robust empirical method to isolate the diode current from measured “shunt-contaminated” forward dark IV . We find that space-charge-limited current provides the best qualitative explanation for the observed features of the shunt current. Finally, we discuss the possible physical origin of localized shunt paths in the light of experimental …
Identification, Characterization, And Implications Of Shadow Degradation In Thin Film Solar Cells, Sourabh Dongaonkar, Karthik Y, Dapeng Wang, Michel Frei, Souvik Mahapatra, Muhammad Alam
Identification, Characterization, And Implications Of Shadow Degradation In Thin Film Solar Cells, Sourabh Dongaonkar, Karthik Y, Dapeng Wang, Michel Frei, Souvik Mahapatra, Muhammad Alam
Sourabh Dongaonkar
We describe a comprehensive study of intrinsicreliability issue arising from partial shadowing of photovoltaicpanels (e.g., a leaf fallen on it, a nearby tree casting a shadow,etc.). This can cause the shaded cells to be reverse biased, causingdark current degradation. In this paper, (1) we calculate thestatistical distribution of reverse bias stress arising from variousshading configurations, (2) identify the components of darkcurrent, and provide a scheme to isolate them, (3) characterizethe effect of reverse stress on the dark current of a-Si:H p-i-ncells, and (4) finally, combine these features of degradationprocess with shadowing statistics, to project ‘shadow-degradation’ (SD) over the operating lifetime …
Physics And Statistics Of Non-Ohmic Shunt Conduction And Metastability In Amorphous Silicon P-I-N Solar Cells, Sourabh Dongaonkar, Karthik Yogendra, Souvik Mahapatra, Muhammad Alam
Physics And Statistics Of Non-Ohmic Shunt Conduction And Metastability In Amorphous Silicon P-I-N Solar Cells, Sourabh Dongaonkar, Karthik Yogendra, Souvik Mahapatra, Muhammad Alam
Sourabh Dongaonkar
In this paper, we present a physical model of the non- Ohmic shunt current ISH in amorphous silicon (a-Si:H) p–i–n solar cells and validate it with detailed measurements. This model is based on space-charge-limited (SCL) transport through localized p–i–p shunt paths. These paths can arise from n-contact metal incorporation in the a-Si:H layer, causing the (n)a-Si:H to be counterdoped to p-type. The model not only explains all the electrical characteristics of preexisting shunts but also provides insight into the metastable switching that is observed in the shunt-dominated region of dark current as well.We first verify the SCL model using simulations …
Mems Resonant Magnetic Field Sensor Based On An Aln/Fegab Bilayer Nano-Plate Resonator, Yu Hui, Tianxiang Nan, Nian Sun, Matteo Rinaldi
Mems Resonant Magnetic Field Sensor Based On An Aln/Fegab Bilayer Nano-Plate Resonator, Yu Hui, Tianxiang Nan, Nian Sun, Matteo Rinaldi
Matteo Rinaldi
This paper reports on the first demonstration of an ultra-miniaturized, high frequency (215 MHz) and high sensitivity MEMS resonant magnetic field sensor based on an AlN/FeGaB bilayer nano-plate resonator capable of detecting magnetic field at nano-Tesla level. Despite of the reduced volume and the high operating frequency of the sensor, high electromechanical performances were achieved (quality factor Q ≈ 511 and electromechanical coupling coefficient kt² ≈ 1.63%). This first prototype was characterized for different magnetic field levels from 0 to 152 Oe showing a frequency sensitivity of ~ 1 Hz/nT and a limit of detection of ~ 10 nT.
Cause And Prevention Of Moisture-Induced Degradation Of Resistance Random Access Memory Nanodevices, Albert Chen
Cause And Prevention Of Moisture-Induced Degradation Of Resistance Random Access Memory Nanodevices, Albert Chen
Albert B Chen
Dielectric thin films in nanodevices may absorb moisture, leading to physical changes and property/performance degradation, such as altered data storage and readout in resistance random access memory. Here we demonstrate using a nanometallic memory that such degradation proceeds via nanoporosity, which facilitates water wetting in otherwise nonwetting dielectrics. Electric degradation only occurs when the device is in the charge-storage state, which provides a nanoscale dielectrophoretic force directing H2O to internal field centers (sites of trapped charge) to enable bond rupture and charged hydroxyl formation. While these processes are dramatically enhanced by an external DC or AC field and electron-donating electrodes, …
Demonstration And Modeling Of Multi-Bit Resistance Random Access Memory, Albert Chen
Demonstration And Modeling Of Multi-Bit Resistance Random Access Memory, Albert Chen
Albert B Chen
Although intermediates resistance states are common in resistance random access memory (RRAM), two-way switching among them has not been demonstrated. Using a nanometallic bipolar RRAM, we have illustrated a general scheme for writing/rewriting multi-bit memory using voltage pulses. Stability conditions for accessing intermediate states have also been determined in terms of a state distribution function and the weight of serial load resistance. A multi-bit memory is shown to realize considerable space saving at a modest decrease of switching speed.
Vacuum Microelectronic Integrated Differential Amplifier, S. Hsu, W. Kang, J. Davidson, J. Huang, David Kerns, Jr.
Vacuum Microelectronic Integrated Differential Amplifier, S. Hsu, W. Kang, J. Davidson, J. Huang, David Kerns, Jr.
David V. Kerns
Reported is a novel vacuum field emission transistor (VFET) differential amplifier (diff-amp) utilising nanocrystalline diamond emitters with self-aligned gate partitions. The integrated VFET diff-amp was fabricated by a dual-mask self-aligned mould transfer method in conjunction with chemical vapour deposited nanodiamond. Identical pairs of devices with well-matched field emission transistor characteristics were obtained, realising a negligible common-mode gain, high differential-mode gain, and large common-mode rejection ratio (CMRR) of 55 dB. The emission current was validated by a modified Fowler-Nordheim equation in transistor configuration, and the CMRR was modelled by an equivalent half-circuit with the calculated result found to agree well with …
Terahertz And Microwave Detection Using Metallic Single Wall Carbon Nanotubes, Enrique Carrion
Terahertz And Microwave Detection Using Metallic Single Wall Carbon Nanotubes, Enrique Carrion
Enrique A Carrion
Carbon nanotubes (CNTs) are promising nanomaterials for high frequency applications due to their unique physical characteristics. CNTs have a low heat capacity, low intrinsic capacitance, and incredibly fast thermal time constants. They can also exhibit ballistic transport at low bias, for both phonons and electrons, as evident by their fairly long mean free paths. However, despite the great potential they present, the RF behavior of these nanostructures is not completely understood. In order to explore this high frequency regime we studied the microwave (MW) and terahertz (THz) response of individual and bundled single wall nanotube based devices. This thesis is …
Power Mems And Microengines, Alan Epstein, Stephen Senturia, G. Ananthasuresh, Arturo Ayon, Kenneth Breuer, Kuo-Shen Chen, Fredric Ehrich, Gautam Gauba, Reza Ghodssi, C. Groshenry, Stuart Jacobson, Jeffrey Lang, Chuang-Chia Lin, Amit Mehra, José Oscar Mur-Miranda, Steve Nagle, D. Orr, Ed Piekos, Martin Schmidt, Gregory Shirley, Mark Spearing, Choon Tan, Sheng-Yang Tzeng, Ian Waitz
Power Mems And Microengines, Alan Epstein, Stephen Senturia, G. Ananthasuresh, Arturo Ayon, Kenneth Breuer, Kuo-Shen Chen, Fredric Ehrich, Gautam Gauba, Reza Ghodssi, C. Groshenry, Stuart Jacobson, Jeffrey Lang, Chuang-Chia Lin, Amit Mehra, José Oscar Mur-Miranda, Steve Nagle, D. Orr, Ed Piekos, Martin Schmidt, Gregory Shirley, Mark Spearing, Choon Tan, Sheng-Yang Tzeng, Ian Waitz
José Oscar Mur-Miranda
MIT is developing a MEMS-based gas turbine generator. Based on high speed rotating machinery, this 1 cm diameter by 3 mm thick SiC heat engine is designed to produce 10-20 W of electric power while consuming 10 grams/hr of H2. Later versions may produce up to 100 W using hydrocarbon fuels. The combustor is now operating and an 80 W micro-turbine has been fabricated and is being tested. This engine can be considered the first of a new class of MEMS device, power MEMS, which are heat engines operating at power densities similar to those of the best large scale …
Degradation Uniformity Of Rf-Power Gaas Phemts Under Electrical Stress, Anita Villanueva, Jesus Del Alamo, Takayuki Hisaka, Kazuo Hayashi, Mark Somerville
Degradation Uniformity Of Rf-Power Gaas Phemts Under Electrical Stress, Anita Villanueva, Jesus Del Alamo, Takayuki Hisaka, Kazuo Hayashi, Mark Somerville
Mark Somerville
We have studied the electrical degradation of RF-power PHEMTs by means of in situ 2-D light-emission measurements. Electroluminescence originates in the recombination of holes that have been generated by impact ionization. The local light intensity, thus, maps the electric-field distribution at the drain side of the device. This allows us to probe the uniformity of electrical degradation due to electric-field-driven mechanisms. We find that electrical degradation proceeds in a highly nonuniform manner across the width of the device. In an initial phase, degradation takes place preferentially toward the center of the gate finger. In advanced stages of degradation, the edges …
Determining Dominant Breakdown Mechanisms In Inp Hemts, Mark Somerville, Chris Putnam, Jesus Del Alamo
Determining Dominant Breakdown Mechanisms In Inp Hemts, Mark Somerville, Chris Putnam, Jesus Del Alamo
Mark Somerville
We present a new technique for determining the dominant breakdown mechanism in InAlAs-InGaAs high-electron mobility transistors. By exploiting both the temperature dependence and the bias dependence of different physical mechanisms, we are able to discriminate impact ionization gate current from tunneling and thermionic field emission gate current in these devices. Our results suggest that the doping level of the supply layers plays a key role in determining the relative importance of these two effects.
Film Thickness Constraints For Manufacturable Strained Silicon Cmos, J. Fiorenza, G. Braithwaite, C. Leitz, M. Currie, J. Yap, F. Singaporewala, V. Yang, T. Langdo, J. Carlin, Mark Somerville, A. Lochtefeld, H. Badawi, M. Bulsara
Film Thickness Constraints For Manufacturable Strained Silicon Cmos, J. Fiorenza, G. Braithwaite, C. Leitz, M. Currie, J. Yap, F. Singaporewala, V. Yang, T. Langdo, J. Carlin, Mark Somerville, A. Lochtefeld, H. Badawi, M. Bulsara
Mark Somerville
This paper studies the effect of the strained silicon thickness on the characteristics of strained silicon MOSFETs on SiGe virtual substrates. NMOSFETs were fabricated on strained silicon substrates with various strained silicon thicknesses, both above and below the strained silicon critical thickness. The low field electron mobility and subthreshold characteristics of the devices were measured. Low field electron mobility is increased by about 1.8 times on all wafers and is not significantly degraded on any of the samples, even for a strained silicon thickness far greater than the critical thickness. From the subthreshold characteristics, however, it is shown that the …
Physical Mechanisms Limiting The Manufacturing Uniformity Of Millimeter-Wave Power Inp Hemt's, Sergei Krupenin, Roxann Blanchard, Mark Somerville, Jesus Del Alamo, K. Duh, Pane Chao
Physical Mechanisms Limiting The Manufacturing Uniformity Of Millimeter-Wave Power Inp Hemt's, Sergei Krupenin, Roxann Blanchard, Mark Somerville, Jesus Del Alamo, K. Duh, Pane Chao
Mark Somerville
We have developed a methodology to diagnose the physical mechanisms limiting the manufacturing uniformity of millimeter-wave power InAlAs/InGaAs HEMT's on InP. A statistical analysis was carried out on dc figures of merit obtained from a large number of actual devices on an experimental wafer. Correlation studies and principal component analysis of the results indicated that variations in Si delta-doping concentration introduced during molecular-beam epitaxy accounted for more than half of the manufacturing variance. Variations in the gate-source distance that is determined by the electron-beam alignment in the gate formation process were found to be the second leading source of manufacturing …
Strained Si On Insulator Technology: From Materials To Devices, T. Langdo, M. Currie, Z.-Y. Cheng, J. Fiorenza, M. Erdtmann, G. Braithwaite, C. Leitz, C. Vineis, J. Carlin, A. Lochtefeld, M. Bulsara, Isaac Lauer, Dimitri Antoniadis, Mark Somerville
Strained Si On Insulator Technology: From Materials To Devices, T. Langdo, M. Currie, Z.-Y. Cheng, J. Fiorenza, M. Erdtmann, G. Braithwaite, C. Leitz, C. Vineis, J. Carlin, A. Lochtefeld, M. Bulsara, Isaac Lauer, Dimitri Antoniadis, Mark Somerville
Mark Somerville
SiGe-free strained Si on insulator (SSOI) is a new material system that combines the carrier transport advantages of strained Si with the reduced capacitance and improved scalability of thin film silicon on insulator (SOI). We demonstrate fabrication of 20% Ge equivalent strain level SSOI substrates with Si thicknesses of 100 and 400 Å by hydrogen-induced layer transfer of strained Si layers from high quality graded SiGe virtual substrates. The substrate properties are excellent: wafer scale strained Si film thickness uniformities are better than 8%, strained Si surface roughnesses are better than 0.5 nm RMS, and robust tensile strain levels are …
Fully Depleted N-Mosfets On Supercritical Thickness Strained Soi, Isaac Lauer, T. Langdo, Z.-Y. Cheng, J. Fiorenza, G. Braithwaite, M. Currie, C. Leitz, A. Lochtefeld, H. Badawi, M. Bulsara, Mark Somerville, Dimitri Antoniadis
Fully Depleted N-Mosfets On Supercritical Thickness Strained Soi, Isaac Lauer, T. Langdo, Z.-Y. Cheng, J. Fiorenza, G. Braithwaite, M. Currie, C. Leitz, A. Lochtefeld, H. Badawi, M. Bulsara, Mark Somerville, Dimitri Antoniadis
Mark Somerville
Strained silicon-on-insulator (SSOI) is a new material system that combines the carrier transport advantages of strained Si with the reduced parasitic capacitance and improved MOSFET scalability of thin-film SOI. We demonstrate fabrication of highly uniform SiGe-free SSOI wafers with 20% Ge equivalent strain and report fully depleted n-MOSFET results. We show that enhanced mobility is maintained in strained Si films transferred directly to SiO2 from relaxed Si0.8Ge0.2 virtual substrates, even after a generous MOSFET fabrication thermal budget. Further, we find the usable strained-Si thickness of SSOI significantly exceeds the critical thickness of strained Si/SiGe without deleterious leakage current effects typically …
An Autozeroing Floating-Gate Amplifier, Paul Hasler, Bradley Minch, Chris Diorio
An Autozeroing Floating-Gate Amplifier, Paul Hasler, Bradley Minch, Chris Diorio
Bradley Minch
We have developed a bandpass floating-gate amplifier that uses tunneling and pFET hot-electron injection to set its dc operating point adaptively. Because the hot-electron injection is an inherent part of the pFET's behavior, we obtain this adaptation with no additional circuitry. Because the gate currents are small, the circuit exhibits a high-pass characteristic with a cutoff frequency less than 1 Hz. The high-frequency cutoff is controlled electronically, as is done in continuous-time filters. We have derived analytical models that completely characterize the amplifier and that are in good agreement with experimental data for a wide range of operating conditions and …
Integration Of Chemical Sensing And Electrowetting Actuation On Chemoreceptive Neuron Mos (Cνmos) Transistors, Nick Shen, Zengtao Liu, Blake Jacquot, Bradley Minch, Edwin Kan
Integration Of Chemical Sensing And Electrowetting Actuation On Chemoreceptive Neuron Mos (Cνmos) Transistors, Nick Shen, Zengtao Liu, Blake Jacquot, Bradley Minch, Edwin Kan
Bradley Minch
An integration of chemical sensors and electrowetting actuators based on the chemoreceptive neuron MOS (CνMOS) transistors has brought forth a novel system-on-chip approach to the microfluidic system. The extended floating-gate structure of the CνMOS transistors enables monolithic sensing and actuating schemes. The sensors with generic chemical receptive areas have been characterized with various fluids, and have demonstrated a high sensitivity from the current differentiation and a large dynamic range from threshold-voltage shifts in sensing polar and electrolytic liquids. The actuators have illustrated valve functions based on contact-angle modification by nonvolatile charge injection into the channel wall. Electrochemical models for sensing …
Charge-Based Chemical Sensors: A Neuromorphic Approach With Chemoreceptive Neuron Mos (Cvmos) Transistors, Nick Shen, Zengtao Liu, Chungho Lee, Bradley Minch, Edwin Kan
Charge-Based Chemical Sensors: A Neuromorphic Approach With Chemoreceptive Neuron Mos (Cvmos) Transistors, Nick Shen, Zengtao Liu, Chungho Lee, Bradley Minch, Edwin Kan
Bradley Minch
A novel chemoreceptive neuron MOS (CνMOS) transistor with an extended floating-gate structure has been designed with several individual features that significantly facilitate system integration of chemical sensing. We have fabricated CνMOS transistors with generic molecular receptive areas and have characterized them with various fluids. We use an insulating polymer layer to provide physical and electrical isolation for sample fluid delivery. Experimental results from these devices have demonstrated both high sensitivity via current differentiation and large dynamic range from threshold voltage shifts in sensing both polar and electrolytic liquids. We have established electrochemical models for both steady-state and transient analyses. Our …
Simulation Of Gallium Arsenide Electroluminescence Spectra In Avalanche Breakdown Using Self-Absorption And Recombination Models, David Kerns, Sherra Kerns, M Lahbabi, A Ahaitouf, E Abarkan, M Fliyou, A Hoffmann, J Charles, Bharat Bhuva
Simulation Of Gallium Arsenide Electroluminescence Spectra In Avalanche Breakdown Using Self-Absorption And Recombination Models, David Kerns, Sherra Kerns, M Lahbabi, A Ahaitouf, E Abarkan, M Fliyou, A Hoffmann, J Charles, Bharat Bhuva
Sherra E. Kerns
Light emission from gallium arsenide (GaAs) p–n junctions biased in avalanche breakdown have been modeled over the range of 1.4–3.4 eV. The model emphasizes direct and indirect recombination processes and bulk self-absorption. Comparisons between measured and simulated spectra for sample junctions from custom and commercially fabricated GaAs devices demonstrate that the model is simple, accurate, and consistent with fundamental physical device theory. The model also predicts the junction depth with accuracy.
A Study Of Diamond Field Emission Using Micro-Patterned Monolithic Diamond Tips With Different Sp2 Contents, David Kerns, A Wisitsora-At, W Kang, J Davidson
A Study Of Diamond Field Emission Using Micro-Patterned Monolithic Diamond Tips With Different Sp2 Contents, David Kerns, A Wisitsora-At, W Kang, J Davidson
David V. Kerns
Electron field emission from an array of micro-patterned monolithic diamond tips with varying sp2 content has been systematically investigated. The experimental results show that the field emission characteristics can be improved and the turn-on electric field can be reduced more than 50% by increasing sp2 content. Two hypotheses are proposed as an explanation of the effect of sp2 content on the field emission characteristics of diamond tips: the lowering of the work function due to defect-induced band generated bysp2 content in the diamond lattice and an increase in the field enhancement factor due to embedded sp2–diamond–sp2 cascaded microstructures.
Simulation Of Gallium Arsenide Electroluminescence Spectra In Avalanche Breakdown Using Self-Absorption And Recombination Models, David Kerns, Sherra Kerns, M Lahbabi, A Ahaitouf, E Abarkan, M Fliyou, A Hoffmann, J Charles, Bharat Bhuva
Simulation Of Gallium Arsenide Electroluminescence Spectra In Avalanche Breakdown Using Self-Absorption And Recombination Models, David Kerns, Sherra Kerns, M Lahbabi, A Ahaitouf, E Abarkan, M Fliyou, A Hoffmann, J Charles, Bharat Bhuva
David V. Kerns
Light emission from gallium arsenide (GaAs) p–n junctions biased in avalanche breakdown have been modeled over the range of 1.4–3.4 eV. The model emphasizes direct and indirect recombination processes and bulk self-absorption. Comparisons between measured and simulated spectra for sample junctions from custom and commercially fabricated GaAs devices demonstrate that the model is simple, accurate, and consistent with fundamental physical device theory. The model also predicts the junction depth with accuracy.
Analysis Of Scratches Formed On Oxide Surface During Chemical Mechanical Planarization, Jae-Gon Choi, Y. Prasad, In-Kwon Kim, In-Gon Kim, Woo-Jin Kim, Ahmed Busnaina, Jin-Goo Park
Analysis Of Scratches Formed On Oxide Surface During Chemical Mechanical Planarization, Jae-Gon Choi, Y. Prasad, In-Kwon Kim, In-Gon Kim, Woo-Jin Kim, Ahmed Busnaina, Jin-Goo Park
Jin-Goo Park
Scratch formation on patterned oxide wafers during the chemical mechanical planarization process was investigated. Silica and ceria slurries were used for polishing the experiments to observe the effect of abrasives on the scratch formation. Interlevel dielectric patterned wafers were used to study the scratch dimensions, and shallow trench isolation patterned wafers were used to study the effect of polishing parameters, such as pressure and rotational speed (head/platen). Similar shapes of scratches (chatter type) were observed with both types of slurries. The length of the scratch formed might be related to the period of contact between the wafer and the pad. …
A Parallel Circuit Model For Multi-State Resistive-Switching Random Access Memory, Albert Chen
A Parallel Circuit Model For Multi-State Resistive-Switching Random Access Memory, Albert Chen
Albert B Chen
Large, rapidly growing literature is available on bipolar resistive-switching random access memories (RRAM) made of myriad of simple and advanced materials. Many of them exhibit similar resistance switching behavior but, until now, no unifying model can allow quantification of their voltage and time responses. Using a simple parallel circuit model, these responses of a newly discovered RRAM made of a thin-film random material are successfully analyzed. The analysis clearly reveals a large population of intermediate states with remarkably similar switching characteristics. Such modeling framework based on simple circuit constructs also appears applicable to several RRAM made of other materials. This …
Modeling All Spin Logic: Multi-Magnet Networks Interacting Via Spin Currents, Srikant Srinivasan
Modeling All Spin Logic: Multi-Magnet Networks Interacting Via Spin Currents, Srikant Srinivasan
Srikant Srinivasan
All-spin logic (ASL) represents a new approach to information processing where the roles of charges and capacitors in CMOS are played by spins and magnets. This paper (1) summarizes our earlier work on the input-output isolation and intrinsic directivity of ASL devices, (2) uses an experimentally benchmarked simulator for multimagnet networks coupled by spin transport channels to demonstrate a combinational NAND gate, and (3) describes the natural mapping of such ASL networks into neuromorphic circuits suitable for hybrid analog/digital information processing.
Purely Electronic Switching With High Uniformity, Resistance Tunability, And Good Retention In Pt-Dispersed Sio2 Thin Films For Reram, Albert Chen
Albert B Chen
Resistance switching memory operating by a purely electronic switching mechanism, which was first realized in Pt-dispersed SiO2 thin films, satisfies criteria including high uniformity, fast switching speed, and long retention for non-volatile memory application. This resistive element obeys Ohm's law for the area dependence, but its resistance exponentially increases with the film thickness, which provides new freedom to tailor the device characteristics.
Direct Measurement Of Graphene Adhesion On Silicon Surface By Intercalation Of Nanoparticles, Zong Zong, Chia-Ling Chen, Mehmet Dokmeci, Kai-Tak Wan
Direct Measurement Of Graphene Adhesion On Silicon Surface By Intercalation Of Nanoparticles, Zong Zong, Chia-Ling Chen, Mehmet Dokmeci, Kai-Tak Wan
Mehmet R. Dokmeci
We report a technique to characterize adhesion of monolayered/multilayered graphene sheets on silicon wafer. Nanoparticles trapped at graphene-silicon interface act as point wedges to support axisymmetric blisters. Local adhesion strength is found by measuring the particle height and blister radius using a scanning electron microscope. Adhesion energy of the typical graphene-silicon interface is measured to be 151±28 mJ/m2. The proposed method and our measurements provide insights in fabrication and reliability of microelectromechanical/nanoelectromechanical systems.
Low-Voltage And Short-Channel Pentacene Field-Effect Transistors With Top-Contact Geometry Using Parylene-C Shadow Masks, Yoonyoung Chung, Boris Murmann, Selvapraba Selvarasah, Mehmet Dokmeci, Zhenan Bao
Low-Voltage And Short-Channel Pentacene Field-Effect Transistors With Top-Contact Geometry Using Parylene-C Shadow Masks, Yoonyoung Chung, Boris Murmann, Selvapraba Selvarasah, Mehmet Dokmeci, Zhenan Bao
Mehmet R. Dokmeci
We have fabricated high-performance top-contact pentacene field-effect transistors using a nanometer-scale gate dielectric and parylene-C shadow masks. The high-capacitance gate dielectric, deposited by atomic layer deposition of aluminum oxide, resulted in a low operating voltage of 2.5 V. The flexible and conformal parylene-C shadow masks allowed fabrication of transistors with channel lengths of L = 5, 10, and 20 μm. The field-effect mobility of the transistors was μ = 1.14 (±0.08) cm²/V s on average, and the IMAX/IMIN ratio was greater than 10⁶.
Unidirectional Information Transfer With Cascaded All Spin Logic Devices: A Ring Oscillator, Srikant Srinivasan
Unidirectional Information Transfer With Cascaded All Spin Logic Devices: A Ring Oscillator, Srikant Srinivasan
Srikant Srinivasan
The authors have presented the first simulator that simultaneously describes magnetization dynamics as well as spin transport in multi-magnet ASL networks and used it to demonstrate the possibility of large scale functional spin logic blocks through the example of an All Spin ring oscillator.
Switching Energy-Delay Of All Spin Logic Devices, Srikant Srinivasan
Switching Energy-Delay Of All Spin Logic Devices, Srikant Srinivasan
Srikant Srinivasan
A recent proposal called all spin logic (ASL) proposes to store information in nanomagnets that communicate with spin currents in order to construct spin based digital circuits. We present a coupled magnetodynamics/spin-transport model for ASL devices that is based on established physics and is benchmarked against available experimental data. This model is used to show the linear dependence of switching energy and quadratic dependence of energy-delay of ASL devices on the number of Bohr magnetons comprising a nanomagnet. A scaling scheme that could lower the energy-delay of spin-torque switching while maintaining thermal stability is discussed.
Valley Splitting In Si Quantum Dots Embedded In Sige, Srikant Srinivasan
Valley Splitting In Si Quantum Dots Embedded In Sige, Srikant Srinivasan
Srikant Srinivasan
We examine energy spectra of Si quantum dots embedded in Si0.75Ge0.25 buffers using atomistic numerical calculations for dimensions relevant to qubit implementations. The valley degeneracy of the lowest orbital state is lifted and valley splitting fluctuates with monolayer frequency as a function of the dot thickness. For dot thicknesses ≤ 6 nm, valley splitting is found to be >150 μeV. Using the unique advantage of atomistic calculations, we analyze the effect of buffer disorder on valley splitting. Disorder in the buffer leads to the suppression of valley splitting by a factor of 2.5; the splitting fluctuates with ≈ 20 μeV …