A5028373521- Thermal properties of materials
- Advanced Thermoelectric Materials and Devices
- Force Microscopy Techniques and Applications
- Thermal Radiation and Cooling Technologies
- Mechanical and Optical Resonators
- Nanopore and Nanochannel Transport Studies
- Carbon Nanotubes in Composites
- Microfluidic and Capillary Electrophoresis Applications
- Adhesion, Friction, and Surface Interactions
- Thermography and Photoacoustic Techniques
- Heat Transfer and Optimization
- Molecular Junctions and Nanostructures
- Advanced Thermodynamics and Statistical Mechanics
- Advanced MEMS and NEMS Technologies
- Graphene research and applications
- Nanowire Synthesis and Applications
- Near-Field Optical Microscopy
- Microfluidic and Bio-sensing Technologies
- Surface and Thin Film Phenomena
- Advancements in Semiconductor Devices and Circuit Design
- Fuel Cells and Related Materials
- Integrated Circuits and Semiconductor Failure Analysis
- Analytical Chemistry and Sensors
- Electronic and Structural Properties of Oxides
- Advanced biosensing and bioanalysis techniques
Stanford University
2016-2025
SLAC National Accelerator Laboratory
2017-2023
Stanford Health Care
2018-2021
Breakthrough
2021
Stanford Medicine
2018-2020
University of California, Santa Barbara
1993-2017
Linac Coherent Light Source
2017
Lawrence Berkeley National Laboratory
2004-2016
University of California, Berkeley
2006-2016
National University of Singapore
2014
The thermal conductivity and thermoelectric power of a single carbon nanotube were measured using microfabricated suspended device. observed is more than 3000 W/K m at room temperature, which 2 orders magnitude higher the estimation from previous experiments that used macroscopic mat samples. temperature dependence nanotubes exhibits peak 320 K due to onset umklapp phonon scattering. shows linear with value 80 microV/K temperature.
Rapid progress in the synthesis and processing of materials with structure on nanometer length scales has created a demand for greater scientific understanding thermal transport nanoscale devices, individual nanostructures, nanostructured materials. This review emphasizes developments experiment, theory, computation that have occurred past ten years summarizes present status field. Interfaces between become increasingly important small scales. The conductance many solid–solid interfaces been...
The thermal conductivities of individual single crystalline intrinsic Si nanowires with diameters 22, 37, 56, and 115 nm were measured using a microfabricated suspended device over temperature range 20–320 K. Although the had well-defined order, conductivity observed was more than two orders magnitude lower bulk value. strong diameter dependence in ascribed to increased phonon-boundary scattering possible phonon spectrum modification.
A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, management nanoscale electronics, and nanoparticles for medical therapies are motivating studies the applied physics transport at nanoscale. This review emphasizes developments in experiment, theory, computation past ten years summarizes present status field. Interfaces become increasingly important on small...
Roughness measurements by optical interferometry and scanning tunneling microscopy on a magnetic thin-film rigid disk surface have shown that its is fractal in nature. This leads to scale-dependence of statistical parameters such as r.m.s height, slope curvature, which are extensively used classical models contact between rough surfaces. Based the scale-independent roughness parameters, new model isotropic surfaces developed. The predicts all spots area smaller than critical plastic contact....
We demonstrated nanoscale solid-state thermal rectification. High-thermal-conductivity carbon and boron nitride nanotubes were mass-loaded externally inhomogeneously with heavy molecules. The resulting system yields asymmetric axial conductance greater heat flow in the direction of decreasing mass density. effect cannot be explained by ordinary perturbative wave theories, instead we suggest that solitons may responsible for phenomenon. Considering important role electrical rectifiers...
A proper characterization of the multiscale topography rough surfaces is very crucial for understanding several tribological phenomena. Although nature warrants a scale-independent characterization, conventional techniques use scale-dependent statistical parameters such as variances height, slope and curvature which are shown to be functions surface magnification. Roughness measurements on magnetic tape, smooth textured thin film rigid disks, machined stainless steel show that their spectra...
By trapping molecules between two gold electrodes with a temperature difference across them, the junction Seebeck coefficients of 1,4-benzenedithiol (BDT), 4,4′-dibenzenedithiol, and 4,4′′-tribenzenedithiol in contact were measured at room to be +8.7 ± 2.1 microvolts per kelvin (μV/K), +12.9 2.2 μV/K, +14.2 3.2 respectively (where error is full width half maximum statistical distributions). The positive sign unambiguously indicates p-type (hole) conduction these heterojunctions, whereas Au...
Heat conduction in dielectric thin films is a critical issue the design of electronic devices and packages. Depending on material properties, there exists range film thickness where Fourier law, used for macroscale heat conduction, cannot be applied. This paper shows that this microscale regime, transport by lattice vibrations or phonons can analyzed as radiative transfer problem. Based Boltzmann theory, an equation phonon (EPRT) developed. In acoustically thick limit, ξL ≫ 1, much larger...
Atomic substitution in alloys can efficiently scatter phonons, thereby reducing the thermal conductivity crystalline solids to "alloy limit." Using In0.53Ga0.47As containing ErAs nanoparticles, we demonstrate reduction by almost a factor of 2 below alloy limit and corresponding increase thermoelectric figure merit 2. A theoretical model suggests that while point defects short-wavelength nanoparticles provide an additional scattering mechanism for mid-to-long-wavelength phonons.
We have observed experimentally that the thermal conductance of a 2.76-microm-long individual suspended single-wall carbon nanotube (SWCNT) was very close to calculated ballistic 1-nm-diameter SWCNT without showing signatures phonon-phonon Umklapp scattering for temperatures between 110 and 300 K. Although thermopower can be attributed linear diffusion contribution constant phonon drag effect, there could an additional contact effect.
We have batch-fabricated a microdevice consisting of two adjacent symmetric silicon nitride membranes suspended by long beams for measuring thermophysical properties one-dimensional nanostructures (nanotubes, nanowires, and nanobelts) bridging the membranes. A platinum resistance heater/thermometer is fabricated on each membrane. One membrane can be Joule heated to cause heat conduction through sample other Thermal conductance, electrical Seebeck coefficient measured using this in...
Boiling is a common mechanism for liquid−vapor phase transition and widely exploited in power generation refrigeration devices systems. The efficacy of boiling heat transfer characterized by two parameters: (a) coefficient (HTC) or the thermal conductance; (b) critical flux (CHF) limit that demarcates from high HTC to very low HTC. While increasing CHF has significant impact on system-level energy efficiency, safety, cost, their values water other fluids have essentially remained unchanged...
We report a nanofluidic transistor based on metal-oxide-solution (MOSol) system that is similar to metal-oxide-semiconductor field-effect (MOSFET). Using combination of fluorescence and electrical measurements, we demonstrate gate voltage modulates the concentration ions molecules in channel controls ionic conductance. Our results illustrate efficacy control nanofluidics, which could have broad implications integrated circuits for manipulation biomolecules sub-femtoliter volumes.
We review recent advances in experimental methods for high spatial-resolution and time-resolution thermometry, the application of these related measurements thermal transport low-dimensional structures. Scanning microscopy (SThM) achieves lateral resolutions 50 nm a measurement bandwidth 100 kHz; SThM has been used to characterize differences energy dissipation single-wall multi-wall carbon nanotubes. Picosecond thermoreflectance enables ultrahigh diffusion experiments characterization heat...
Maintaining human body temperature is one of the most basic needs for living, which often consumes a huge amount energy to keep ambient constant. To expand range while maintaining thermal comfort, concept personal management has been recently demonstrated in heating and cooling textiles separately through infrared radiation control. Realizing these two opposite functions within same textile would represent an exciting scientific challenge significant technological advancement. We demonstrate...
▪ Abstract This chapter presents a review of the technology scanning thermal microscopy (SThM) and its applications in thermally probing micro- nanostructured materials devices. We begin by identifying parameters that control temporal temperature resolution thermometry. The discussion SThM research is divided into three main categories: those use (a) thermovoltage-based measurements, (b) electrical resistance techniques, (c) expansion measurements. Within each category we describe numerous...
We demonstrate rectification of ionic transport in a nanofluidic diode fabricated by introducing surface charge discontinuity channel. Device current-voltage (I-V) characteristics agree qualitatively with one-dimensional model at moderate to high concentrations. This study illustrates flow control using patterning channels under bias voltages.
Theoretical modeling of ionic distribution and transport in silica nanotubes, 30 nm diameter 5 μm long, suggest that when the is smaller than Debye length, a unipolar solution counterions created within nanotube coions are electrostatically repelled. By locally modifying surface charge density through gate electrode, ion concentration can be depleted under current significantly suppressed. It proposed this could form basis field-effect transistor.