Thanks to ultrafast acoustics, a better understanding of acoustic dynamics on a short time scale has been obtained and new characterization methods at the nanoscale have been developed. Among the materials that were studied during the development of ultrafast acoustics, nitride based heterostructures play a particular role due to their piezoelectric properties and the possibility to generate phonons with over-THz frequency and bandwidth. Here, we review some of the work performed using this type of structure, with a focus on THz phonon spectroscopy and nanoscopy. First, we present a brief description of the theory of coherent acoustic phonon generation by piezoelectric heterostructure. Then the first experimental observation of coherent acoustic phonon generated by the absorption of ultrashort light pulses in piezoelectric heterostructures is presented. From this starting point, we then present some methods developed to realize customizable phonon generation. Finally we review some more recent applications of these structures, including imaging with a nanometer resolution, broadband attenuation measurements with a frequency up to 1THz and phononic bandgap characterization.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.ultras.2014.09.020 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Direct Observation of Substantial Phonon Nonequilibrium Near Nanoscale Hotspots in Gallium Nitride.
Adv Sci (Weinh)
January 2025
School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei, 430072, P. R. China.
Phonon modal nonequilibrium is believed to widely exist around nanoscale hotspots, which can significantly affect the performance of nano-electronic and optoelectronic devices. However, such a phenomenon has not been explicitly observed in 3D device semiconductors at the nanoscale. Here, by employing a tip-enhanced Raman thermal measurement approach, substantial phonon nonequilibrium in gallium nitride near sub-10 nm laser-excited hotspots is directly revealed for the first time.
View Article and Find Full Text PDFAchieving Ultralow Lattice Thermal Conductivity and High Thermoelectric Performance in BiTeSe Alloys via Introducing Organic & Inorganic Nanoparticles.
Small
January 2025
Key Lab of Photovoltaic and Energy Conservation Materials, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei, 230031, P. R. China.
N-type BiTeSe(BTS) is a state-of-the-art thermoelectric material owing to its excellent thermoelectric properties near room temperatures for commercial applications. However, its performance is restricted by its comparatively low figure of merit ZT. Here, it is shown that a 14% increase in power factor (PF) (at 300 K) can be reached through incorporation of inorganic GaAs nanoparticles due to enhanced thermopower originating from the energy-dependent carrier scattering.
View Article and Find Full Text PDFEffects of Homogeneous Doping on Electron-Phonon Coupling in SrTiO.
Nanomaterials (Basel)
January 2025
Department of Physics and Natural Science Research Institute, University of Seoul, Seoul 02504, Republic of Korea.
Bulk n-type SrTiO (STO) has long been known to possess a superconducting ground state at an exceptionally dilute carrier density. This has raised questions about the applicability of the BCS-Eliashberg paradigm with its underlying adiabatic assumption. However, recent experimental reports have set the pairing gap to the critical temperature (Tc) ratio at the BCS value for superconductivity in Nb-doped STO, even though the adiabaticity condition the BCS pairing requires is satisfied over the entire superconducting dome only by the lowest branch of optical phonons.
View Article and Find Full Text PDFEffects of Intrinsic Defects on the Carrier Lifetime in CdZnTe: Insights from Ab Initio Calculations.
J Phys Chem Lett
January 2025
School of Physics, Nankai University, Tianjin 300071, China.
CdZnTe (CZT) has garnered substantial attention due to its outstanding performance in room-temperature semiconductor radiation detectors, where carrier transport properties are critical for assessing the detector performance. However, due to the complexities of crystal growth, CZT is prone to defects that affect carrier lifetime and mobility. To investigate how defects affect nonequilibrium carrier transport, nonadiabatic molecular dynamics (NAMD) is employed to examine six types of intrinsic defects and their impact on electron-hole (e-h) recombination.
View Article and Find Full Text PDFLattice Anisotropy-Driven Reduction of Phonon Velocities in Black Phosphorus.
ACS Nano
January 2025
James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States.
Phonon dynamics and transport determine how heat is utilized and dissipated in materials. In 2D systems for optoelectronics and thermoelectrics, the impact of nanoscale material structure on phonon propagation is central to controlling thermal conduction. Here, we directly observe in-plane coherent acoustic phonon propagation in black phosphorus (BP) using ultrafast electron microscopy.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!