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KMID : 1059519970410070329
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Journal of the Korean Chemical Society
1997 Volume.41 No. 7 p.329 ~ p.336
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Photoacoustic Investigation of Carrier Transport and Thermal Diffusivity in GaAs and Si
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Lim Jong-Tae
Han Ho-Youn
Park Seung-Han
Kim Ung
Choi Joong-Gill
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Abstract
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Photoacoustic spectroscopy was utilized to investigate the carrier tmnsport and the thermal diffusivity in GaAs and Si. From the frequency dependence of the photoacoustic signal, it is found that heat source was originated from the instantaneous thermahzation process in low frequency region. In high frequency region, however, the heat was generated by the nonradiative bulk recombination and the nonradiative surface recombination processes. It was also shown that the photoacoustic effects in GaAs of a direct band gap were governed by all three processes and those in Si of an indirect band gap were produced by the instantaneous thermalization and the nonradiative bulk recombination only. The phase of the photoacoustic signal showed a minimum value in GaAs. In Si, the phase of the photoacoustic signal was monotonically decreased as the modulation frequency was increased, demonstrating the above-mentioned mechanisms of the generation of heat. By measuring the photoacoustic signal, thermal diffusivities of semiconductors were determined to be ~0.35 cm2/s for GaAs and ~1.24cm2/s for Si. In addition, the similar values of thermal diffusivities were obtained from the curve fitting of photoacoustic phase spectra.
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