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Photothermal deflection measurement on heat transport in GaAs epitaxial layers

By C P Girijavallabhan, P Radhakrishnan, V P N Nampoori and D George Sajan


In this paper, we report the in-plane and cross-plane measurements of the thermal diffusivity of double epitaxial layers of n-type GaAs doped with various concentrations of Si and a p-type Be-doped GaAs layer grown on a GaAs substrate by the molecular beam epitaxial method, using the laser-induced nondestructive photothermal deflection technique. The thermal diffusivity value is evaluated from the slope of the graph of the phase of the photothermal deflection signal as a function of pump-probe offset. Analysis of the data shows that the cross-plane thermal diffusivity is less than that of the in-plane thermal diffusivity. It is also seen that the doping concentration has a great influence on the thermal diffusivity value. Measurement of p-type Be-doped samples shows that the nature of the dopant also influences the effective thermal diffusivity value. The results are interpreted in terms of a phonon-assisted heat transfer mechanism and the various scattering process involved in the propagation of phonons

Topics: Photothermal deflection, heat transport, GaAs epitaxial layers, Doping, thermal diffusivity, phonons
Publisher: 'American Physical Society (APS)'
Year: 2003
DOI identifier: 10.1103/PhysRevB.68.165319
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