Photoacoustic study of the effect of doping concentration on the transport properties of GaAs epitaxial layers

Abstract

We report a photoacoustic (PA) study of the thermal and transport properties of a GaAs epitaxial layer doped with Si at varying doping concentration, grown on GaAs substrate by molecular beam epitaxy. The data are analyzed on the basis of Rosencwaig and Gersho's theory of the PA effect. The amplitude of the PA signal gives information about various heat generation mechanisms in semiconductors. The experimental data obtained from the measurement of the PA signal as a function of modulation frequency in a heat transmission configuration were fitted with the phase of PA signal obtained from the theoretical model evaluated by considering four parameters-viz., thermal diffusivity, diffusion coefficient, nonradiative recombination time, and surface recombination velocity-as adjustable parameters. It is seen from the analysis that the photoacoustic technique is sensitive to the changes in the surface states depend on the doping concentration. The study demonstrates the effectiveness of the photoacoustic technique as a noninvasive and nondestructive method to measure and evaluate the thermal and transport properties of epitaxial layers.

Photoacoustic Method for Measurement of Thermal Effusivity of Fe3O4 Nanofluid

“…The obtained value for parameter (P 2 ≈ 1.28, Table 1) shows that the obtained PA signal has inverse frequency dependence in accordance with RG theory. George et al [22] used log-log plot to analyze the thermal diffusivity of GaAs semiconductor layer, and various mechanisms responsible to generate the signal have been discussed. Since the data and applied model are the same, residual error remains the same in normal and log-log scale (inside Figures 4(c) and 4(d)).…”