Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 12 of 12 for “"phonon imaging"”.
-
Phonon imaging
This thesis describes the development of the phonon imaging method. This technique permits the direct measurement of the angular and temporal distribution of phonons emitted from a point source of heat in insulators at low temperatures. It is a derivative of the ballistic heat pulse method, but one …
-
Dispersive phonon imaging in III-V semiconductors
… transport properties of high-frequency acoustic phonons are investigated in GaAs, InSb, InP and InAs using the phonon-imaging technique. In this method, a focused laser beam provides a movable heat source on one side of a cooled crystal (~ 2 K). A single small phonon detector on the opposite face …
-
Using Phonon Imaging to Probe Anisotropy in the Superconducting energy Gap of Lead
Submitted by Meng Tao (mengtao2@illinois.edu) on 2012-11-14T18:20:59Z No. of bitstreams: 1 Short_Jonathan.pdf: 7409344 bytes, checksum: 92684f5b5180376dd3bbfabec50d734b (MD5)
-
Study of phonon transmission through solid-solid interfaces and superlattices by phonon imaging
… the low-temperature propagation of heat pulses (phonons) through crystals and across solid-solid interfaces. The phonon imaging technique has been used to examine the angular and temporal dependence of the phonon-flux intensity in several systems, listed below. 1. Phonon focusing in cubic …
-
Probing the Superconducting Gap of Lead With Ballistic Phonons
… erroneous results for temperature dependences of phonon absorption. Instead, we assume that the phonon-imaging experiment creates small regions of raised temperature that contribute non-equilibrium quasiparticles to the system. Accounting for these quasiparticles, we extract consistent values of …
-
High-frequency phonon propagation and detection in III-V semiconductors
… and detection of high frequency acoustic phonons in GaAs and InAs is studied. Phonon imaging is used to study scattering of acoustic phonons in GaAs and angular dispersion of acoustic phonons in InAs. Photoluminescence spectroscopy is used to study the effects of nonequilibrium phonons on …
-
Acoustic waves in crystals: I. Ultrasonic flux imaging and internal diffraction. II. Imaging phonons in superconducting niobium
Acoustic wave propagation is studied via imaging techniques in two regimes not previously amenable to such experiments. (I) The low-temperature phonon-imaging technique is extended to ultrasonic frequencies at room temperatures where it is used to study the anisotropic propagation of acoustic waves …
-
The scattering of high-frequency acoustic phonons in silicon and gallium arsenide
… and propagation of high-frequency acoustic phonons in silicon and GaAs are studied at low temperatures ($\le$2K) using the phonon imaging technique. In this technique, a heat source is provided by a focused laser beam which is raster scanned across the surface of the sample which is immersed …
-
High frequency phonon propagation and detection in III-V semiconductors
… and detection of high frequency acoustic phonons in GaAs and InAs is studied. .Phonon imaging is used to study scattering of acoustic phonons in GaAs and angular dispersion of acoustic phonons in InAs. Photoluminescence spectroscopy is used to study the effects of nonequilibrium phonons on …
-
Photo-produced phonons in semiconductors
The techniques of phonon imaging are used in conjunction with photoluminescence measurements to determine the characteristics of optically generated phonon sources in Si, Ge and GaAs at 1.7K. Focused-laser excitation of a semiconductor generates phonons as a byproduct of electronic excitation. A …
-
Phonon scattering by ferroelectric domain walls in potassium dihydrogen phosphate
I have studied phonon scattering by ferroelectric domain walls in KH2P04 (KDP) using thermal conductivity and phonon imaging measurements of samples in both single-domain (poled) and multidomain states. Domains were eliminated by applying a 2- 3kV /em field using evaporated electrodes. Phonon …
-
The scattering of high-frequency acoustic phonons in silicon and GaAs
… and propagation of high-frequency acoustic phonons in silicon and GaAs are studied at low temperatures (~ 2K) using the phonon imaging technique. In this technique, a heat source is provided by a focused laser beam which is raster scanned across the surface of the sample which is immersed in …