Author
Peter Hadley
Other affiliations: Stanford University, Delft University of Technology, Kavli Institute of Nanoscience ...read more
Bio: Peter Hadley is an academic researcher from Graz University of Technology. The author has contributed to research in topics: Josephson effect & Silicon. The author has an hindex of 26, co-authored 90 publications receiving 5445 citations. Previous affiliations of Peter Hadley include Stanford University & Delft University of Technology.
Papers published on a yearly basis
Papers
More filters
TL;DR: This work demonstrates logic circuits with field-effect transistors based on single carbon nanotubes that exhibit a range of digital logic operations, such as an inverter, a logic NOR, a static random-access memory cell, and an ac ring oscillator.
Abstract: We demonstrate logic circuits with field-effect transistors based on single carbon nanotubes. Our device layout features local gates that provide excellent capacitive coupling between the gate and nanotube, enabling strong electrostatic doping of the nanotube from p-doping to n-doping and the study of the nonconventional long-range screening of charge along the one-dimensional nanotubes. The transistors show favorable device characteristics such as high gain (>10), a large on-off ratio (>10(5)), and room-temperature operation. Importantly, the local-gate layout allows for integration of multiple devices on a single chip. Indeed, we demonstrate one-, two-, and three-transistor circuits that exhibit a range of digital logic operations, such as an inverter, a logic NOR, a static random-access memory cell, and an ac ring oscillator.
2,642 citations
TL;DR: Single-crystal field effect transistors of the organic semiconductor dithiophene-tetrathiafulvalene (DT-TTF) were prepared by drop casting and the highest hole mobility observed was 1.4 cm2/Vs, which is the highest reported for an Organic semiconductor not based on pentacene.
Abstract: Single-crystal field effect transistors of the organic semiconductor dithiophene-tetrathiafulvalene (DT-TTF) were prepared by drop casting. Long, thin crystals connected two microfabricated gold electrodes, and a silicon substrate was used as a back gate. The highest hole mobility observed was 1.4 cm2/Vs, which is the highest reported for an organic semiconductor not based on pentacene. A high ON/OFF ratio of at least 7 x 105 was obtained for this device.
301 citations
TL;DR: Organic single-crystal field-effect transistors based on materials related to DT-TTF are presented and a clear correlation between the crystal structure and the electrical characteristics is observed.
Abstract: Recently, it was reported that crystals of the organic material dithiophene-tetrathiafulvalene (DT-TTF) have a high field-effect charge carrier mobility of 1.4 cm2/(V·s). These crystals were formed by a simple drop-casting method, making this material interesting to investigate for possible applications in low-cost electronics. Here, organic single-crystal field-effect transistors based on materials related to DT-TTF are presented and a clear correlation between the crystal structure and the electrical characteristics is observed. The observed relationship between the mobilities in the different crystal structures is strongly corroborated by calculations of both the molecular reorganization energies and the maximum intermolecular transfer integrals. The most suitable materials described here exhibit mobilities that are among the highest reported for organic field-effect transistors and that are the highest reported for solution-processed materials.
251 citations
TL;DR: Bifurcation theory is used to discuss the role that symmetry plays in determining the form and the stability of these oscillations, and it is found that arbitrarily large, dc-biased, arrays of Josephson junctions will phase lock most strongly when the capacitance parameter ${\ensuremath{\beta}}_{c}$1 and the bias current is about the same as the critical current of the individual junctions.
Abstract: We report the results of a stability analysis of coherent oscillations in series arrays of Josephson junctions shunted by a common load. The analysis has found the parameter values for which the coherent, in-phase solution is stable and gives a quantitative measure of the stability. We find that arbitrarily large, dc-biased, arrays of Josephson junctions will phase lock most strongly when the capacitance parameter ${\ensuremath{\beta}}_{c}$\ensuremath{\approxeq}1 and the bias current is about the same as the critical current of the individual junctions. We use bifurcation theory to discuss the role that symmetry plays in determining the form and the stability of these oscillations. Simulations with up to 100 junctions confirm the results of the stability analysis. Arrays of nearly identical junctions are also discussed.
200 citations
TL;DR: It is found that due to the steric, polarizable environment and the structural changes induced by local intermolecular charge delocalization, the calculated lambdareorg for DT-TTF decreases, which is of the same order of the previously reported value found for the isolated pentacene molecule.
Abstract: We report on a computational study to understand the high mobility found in dithiophene-tetrathiafulvalene (DT-TTF) transistors, with respect to that known for pentacene, using an extended measure of the reorganization energy (λreorg). We demonstrate the high importance of considering intermolecular interactions to assess hole-hopping mobilities. We find that due to the steric, polarizable environment and the structural changes induced by local intermolecular charge delocalization, the calculated λreorg for DT-TTF decreases from 0.574 eV in the isolated molecule to 0.042 eV in the crystal embedded molecule, which is of the same order of the previously reported value found for the isolated pentacene molecule, 0.098 eV.
160 citations
Cited by
More filters
28 Jul 2005
TL;DR: PfPMP1）与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。
18,940 citations
TL;DR: Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites; energy storage and energy conversion devices; sensors; field emission displays and radiation sources; hydrogen storage media; and nanometer-sized semiconductor devices, probes, and interconnects.
Abstract: Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites; energy storage and energy conversion devices; sensors; field emission displays and radiation sources; hydrogen storage media; and nanometer-sized semiconductor devices, probes, and interconnects. Some of these applications are now realized in products. Others are demonstrated in early to advanced devices, and one, hydrogen storage, is clouded by controversy. Nanotube cost, polydispersity in nanotube type, and limitations in processing and assembly methods are important barriers for some applications of single-walled nanotubes.
9,693 citations
TL;DR: This approach has the potential of converting mechanical, vibrational, and/or hydraulic energy into electricity for powering nanodevices.
Abstract: We have converted nanoscale mechanical energy into electrical energy by means of piezoelectric zinc oxide nanowire (NW) arrays. The aligned NWs are deflected with a conductive atomic force microscope tip in contact mode. The coupling of piezoelectric and semiconducting properties in zinc oxide creates a strain field and charge separation across the NW as a result of its bending. The rectifying characteristic of the Schottky barrier formed between the metal tip and the NW leads to electrical current generation. The efficiency of the NW-based piezoelectric power generator is estimated to be 17 to 30%. This approach has the potential of converting mechanical, vibrational, and/or hydraulic energy into electricity for powering nanodevices.
6,692 citations
TL;DR: Electronic Coupling in Oligoacene Derivatives: Factors Influencing Charge Mobility, and the Energy-Splitting-in-Dimer Method 3.1.
Abstract: 2.2. Materials 929 2.3. Factors Influencing Charge Mobility 931 2.3.1. Molecular Packing 931 2.3.2. Disorder 932 2.3.3. Temperature 933 2.3.4. Electric Field 934 2.3.5. Impurities 934 2.3.6. Pressure 934 2.3.7. Charge-Carrier Density 934 2.3.8. Size/molecular Weight 935 3. The Charge-Transport Parameters 935 3.1. Electronic Coupling 936 3.1.1. The Energy-Splitting-in-Dimer Method 936 3.1.2. The Orthogonality Issue 937 3.1.3. Impact of the Site Energy 937 3.1.4. Electronic Coupling in Oligoacene Derivatives 938
3,635 citations
TL;DR: In this paper, ultrathin epitaxial graphite films were grown by thermal decomposition on the (0001) surface of 6H−SiC, and characterized by surface science techniques.
Abstract: We have produced ultrathin epitaxial graphite films which show remarkable 2D electron gas (2DEG) behavior. The films, composed of typically three graphene sheets, were grown by thermal decomposition on the (0001) surface of 6H−SiC, and characterized by surface science techniques. The low-temperature conductance spans a range of localization regimes according to the structural state (square resistance 1.5 kΩ to 225 kΩ at 4 K, with positive magnetoconductance). Low-resistance samples show characteristics of weak localization in two dimensions, from which we estimate elastic and inelastic mean free paths. At low field, the Hall resistance is linear up to 4.5 T, which is well-explained by n-type carriers of density 1012 cm-2 per graphene sheet. The most highly ordered sample exhibits Shubnikov−de Haas oscillations that correspond to nonlinearities observed in the Hall resistance, indicating a potential new quantum Hall system. We show that the high-mobility films can be patterned via conventional lithographic...
3,315 citations