A5039113455- Thermal properties of materials
- High-pressure geophysics and materials
- Thermal Radiation and Cooling Technologies
- Diamond and Carbon-based Materials Research
- Surface and Thin Film Phenomena
- Advanced Thermoelectric Materials and Devices
- Silicon Carbide Semiconductor Technologies
- Quantum and electron transport phenomena
- Heat Transfer and Optimization
- Advancements in Semiconductor Devices and Circuit Design
- nanoparticles nucleation surface interactions
University of California, Riverside
2021-2023
The goal of this study is to determine how bulk vibrational properties and interfacial structure affect thermal transport at interfaces in wide band gap semiconductor systems. Time-domain thermoreflectance measurements conductance G are reported for between nitride metals group IV (diamond, SiC, Si, Ge) III–V (AlN, GaN, cubic BN) materials. Group semiconductors have systematic differences properties. Similarly, HfN TiN also vibrationally distinct from each other. Therefore, comparing formed...
We report the results of investigation bulk and surface acoustic phonons in undoped boron-doped single-crystal diamond films using Brillouin-Mandelstam light scattering spectroscopy. The evolution optical same set samples was monitored with Raman It found that frequency group velocity decrease nonmonotonically increasing boron doping concentration, revealing pronounced phonon softening. change shear-horizontal high-frequency pseudo-longitudinal degenerately doped diamond, as compared to...
To better understand the many effects of temperature on optical properties metals, we experimentally and theoretically quantify electron vs. phonon contributions to thermoreflectance spectra gold. We perform a series pump/probe measurements nanoscale Pt/Au bilayers at wavelengths between 400 1000 nm. At all wavelengths, find that changes in temperature, not are primary contributor Au. The is most sensitive wavelength ~480 nm due interband transitions d-states Fermi-level. In near infrared,...
Interfaces often govern the thermal performance of nanoscale devices and nanostructured materials. As a result, accurate knowledge interface conductance is necessary to model temperature response or materials heating. Here, we report boundary between metals insulators that are commonly used in spin-caloritronic experiments. We use time-domain thermoreflectance measure such as Au, Pt, Ta, Cu, Al with garnet oxide substrates, e.g., NiO, yttrium iron (YIG), thulium (TmIG),...
A number of technological applications and scientific experiments require processes for preparing metal multilayers with electronically thermally conductive interfaces. We investigate how in situ vs ex synthesis affect the thermal conductance metal/metal use time-domain thermoreflectance to study transport Au/Fe, Al/Cu, Cu/Pt bilayer samples. quantify effect exposing bottom layer an ambient environment prior deposition top layer. observe that exposure Fe air before depositing Au...
The thermal conductivity Λ of wide bandgap semiconductor thin films, such as AlN, affects the performance high-frequency devices, power and optoelectronics. However, accurate measurements in films with sub-micrometer thicknesses > 100 W m−1 K−1 is challenging. Widely used pump/probe metrologies, time–domain thermoreflectance (TDTR) frequency–domain thermoreflectance, lack spatiotemporal resolution necessary to accurately quantify properties high Λ. In this work, we use a combination...
We report the results of investigation bulk and surface acoustic phonons in undoped boron-doped single-crystal diamond films using Brillouin-Mandelstam light scattering spectroscopy. The evolution optical same set samples was monitored with Raman It found that frequency group velocity decrease non-monotonically increasing boron doping concentration, revealing pronounced phonon softening. change shear horizontal high-frequency pseudo-longitudinal degenerately doped diamond, as compared to...