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Durham e-Theses
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Ultrasonic studies in gallium arsenide and mercury telluride

Cottam, Ronald Ian (1973) Ultrasonic studies in gallium arsenide and mercury telluride. Doctoral thesis, Durham University.



Ultrasonic velocities and attenuation in GaAs and HgTe have been measured between 2 K and room temperature in the frequency range 40 to 750 MHz. An experimental evaluation has been made of the pulse-superposition technique used for measuring the ultrasonic velocities, and particular attention has been paid to determination of the uncertainties involved. A correlation has been found between the ultrasonic pure mode elastic constant combinations of GaAs, HgTe and other III-V and II-VI zinc-blende structure compounds and the group IV elements. The elastic constant temperature dependences are well represented by a phenomenological model based on the Debye phonon frequency spectrum; differences between the model and experimental temperature dependences for the two compounds are compared. The ultrasonic attenuation in GaAs is dominated by damping due to ultrasonic phonon-thermal phonon interactions. The results are interpreted on the basis of the Woodruff and Ehrenreich model and the detailed nature of the phonon-coupling Gruneisen parameter is examined. Two main mechanisms contribute to the low-temperature attenuation in HgTe: phonon-phonon damping and dislocation-resonance damping. A large attenuation peak below liquid nitrogen temperature is explained in terms of thermal unpinning of dislocations.

Item Type:Thesis (Doctoral)
Award:Doctor of Philosophy
Thesis Date:1973
Copyright:Copyright of this thesis is held by the author
Deposited On:13 Nov 2013 15:40

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