Papers by Charles Rettner
Variations in critical dimension (CD) as a function of the proximity of an individual feature to ... more Variations in critical dimension (CD) as a function of the proximity of an individual feature to other exposed areas are continuing to be a problem in the lithography process. For example, the CD uniformity (CDU) may degrade significantly depending on the proximity to densely or sparsely exposed areas. These pattern density effects will continue to get worse and become more
Nature communications, Jan 28, 2017
Rabi oscillations describe the process whereby electromagnetic radiation interacts coherently wit... more Rabi oscillations describe the process whereby electromagnetic radiation interacts coherently with spin states in a non-equilibrium interaction. To date, Rabi oscillations have not been studied in one of the most common spin ensembles in nature: spins in ferromagnets. Here, using a combination of femtosecond laser pulses and microwave excitations, we report the classical analogue of Rabi oscillations in ensemble-averaged spins of a ferromagnet. The microwave stimuli are shown to extend the coherence-time resulting in resonant spin amplification. The results we present in a dense magnetic system are qualitatively similar to those reported previously in semiconductors which have five orders of magnitude fewer spins and which require resonant optical excitations to spin-polarize the ensemble. Our study is a step towards connecting concepts used in quantum processing with spin-transport effects in ferromagnets. For example, coherent control may become possible without the complications ...
Alternative Lithographic Technologies VII, 2015
72nd Device Research Conference, 2014
Numerical modeling is used to explain the origin of the large ON/OFF ratios, ultra-low leakage, a... more Numerical modeling is used to explain the origin of the large ON/OFF ratios, ultra-low leakage, and high ON current densities exhibited by BEOL-friendly Access Devices (AD) based on Cucontaining MIEC materials [1-5]. Motion of large populations of copper ions and vacancies leads to exponential increases in hole current, with a turn-ON voltage that depends on material bandgap. Device simulations match experimental observations as a function of temperature, electrode aspect-ratio, thickness, and device CD.
ACM Journal on Emerging Technologies in Computing Systems, 2013
The memory capacity, computational power, communication bandwidth, energy consumption, and physic... more The memory capacity, computational power, communication bandwidth, energy consumption, and physical size of the brain all tend to scale with the number of synapses, which outnumber neurons by a factor of 10,000. Although progress in cortical simulations using modern digital computers has been rapid, the essential disparity between the classical von Neumann computer architecture and the computational fabric of the nervous system makes large-scale simulations expensive, power hungry, and time consuming. Over the last three decades, CMOS-based neuromorphic implementations of “electronic cortex” have emerged as an energy efficient alternative for modeling neuronal behavior. However, the key ingredient for electronic implementation of any self-learning system—programmable, plastic Hebbian synapses scalable to biological densities—has remained elusive. We demonstrate the viability of implementing such electronic synapses using nanoscale phase change devices. We introduce novel programming...
The Journal of Physical Chemistry, 1982
General expressions are developed for the number of collisions per second a molecule makes with o... more General expressions are developed for the number of collisions per second a molecule makes with other molecules in an effusive molecular beam, a supersonic molecule beam, and a supersonic jet. When characterized by the same density and the same local temperature parameter, we find that the collision frequencies in an effusive beam, supersonic beam, supersonic jet, and a bulb are approximately in the ratio 1:(3/2):3:3. Collision rates appropriate to practical applications are discussed.
The Journal of Chemical Physics
Electron photodetachment from I− ions has been observed using an optogalvanic technique in which ... more Electron photodetachment from I− ions has been observed using an optogalvanic technique in which an electrical discharge in iodine vapor was probed with a pulsed dye laser. The first photodetachment threshold, corresponding to the onset of production of I(2P3/2) atoms, was located at 405.18±0.02 nm giving for the electron affinity Ea(I) =3.0591±0.0001 eV.
The Journal of Chemical Physics
ABSTRACT
We report on domain wall (DW) dynamics in permalloy nanowires. We demonstrate the precessional na... more We report on domain wall (DW) dynamics in permalloy nanowires. We demonstrate the precessional nature of the DW propagation above the Walker breakdown field. Time resolved resistance measurements were performed on 200 nm wide 10 nm thick permalloy nanowires. Oscillations in ...
The Journal of Chemical Physics
ABSTRACT
Science
or current). The stripe pattern disappears again ) when the electric field is removed and the cry... more or current). The stripe pattern disappears again ) when the electric field is removed and the crystal returns back to the high-resistive state. By the atomic force microscope measurement, the surface of the stripe pattern region was confirmed to be flat within 50 nm in height and hence the stripes are not due to groove-like strains. The dark stripe perhaps comes from metallic patches, because the metallic or nondimerized TCNQ stack gives rise to a lower reflectivity in the visible region (11). With use of the sensitivity of the totally symmetric (a g ) mode molecular vibration [CN stretching (v CN ) of TCNQ] to the dimeric (Peierls-like) distortion (10), the microscopic infrared spectroscopy (12) has confirmed that the dimerization is much reduced in the current-flowing region accompanying the stripe pattern, but less so in the nonstripe region (corresponding to the crystal edge part in ). Such a current-path region characterized as the alternative dark and bright regions can be viewed as the periodic phase-segregation into carrier-rich (dark) and -poor (bright) regions.
The crystallization behavior of phase change nanoparticles can provide useful insight into the sc... more The crystallization behavior of phase change nanoparticles can provide useful insight into the scaling properties of phase change materials and of related memory devices. While such nanoparticles can be fabricated using electron-beam lithography, this method is expensive and time-consuming. We have therefore developed fabrication techniques based on self-assembly-based lithographic processes. We have successfully made three types of phase change nanoparticle samples, and have applied time-resolved X-ray diffraction to study their crystallization behavior. Two kinds of self-assembling diblock-copolymers were applied to pattern the phase change materials. In one case self-assembled PS-b-P4VP (polystyrene-b-polyvinylpyridine) was formed on top of an amorphous GeSb phase change film and was used to locally grow SiO 2 dots on top of the P4VP domains. The SiO 2 dots then served as a hard mask to transfer the pattern into the GeSb film using reactive ion etching and ion milling, and isolated 15 nm diameter dots were formed. It was found that these GeSb nanoparticles have a crystallization temperature that is 15ºC lower than comparable blanket film. In the second case cylindrical-phase PS-b-PMMA (polystyrene-b-poly(methylmethacrylate)) films were used. After removal of the PMMA domains, AgInSbTe phase change material was deposited by sputtering using a substrate rf bias and a collimator for better conformality. After lift-off of the PS, isolated AgInSbTe nanoparticles of about 20nm diameter were obtained that showed a crystallization temperature of 175ºC, slightly higher than blanket film (165ºC). The same PS-b-PMMA template was used to deposit newly-developed spin-on phase change material. A GeSeSb precursor was synthesized by dissolving GeSe and Sb 2 Se 3 in hydrazine in the presence of additional elemental selenium. The template was filled with precursor by spin casting, then annealed to form an array of ~20 nm diameter GeSbSe nanoparticles. Finally, the PS template was dissolved to leave the nanoparticles. These arrays crystallized at about 215°C which is 35 °C lower than a blanket film. All of these experiments confirm that phase change devices should scale to well below 20nm.
... Co. Ltd. IBM Almaden Research Center, San Jose, CA Yuan Zhang, Marissa Caldwell, H.-S. Philip... more ... Co. Ltd. IBM Almaden Research Center, San Jose, CA Yuan Zhang, Marissa Caldwell, H.-S. Philip Wong Stanford University Stanford, CA Delia Milliron, Jennifer Cha IBM Almaden Research Center San Jose, CA Abstract Scalability ...
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Papers by Charles Rettner