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arXiv · 1804.05221

Temperature effect on the coupling between coherent longitudinal phonons and plasmons in n- and p-type GaAs

Jianbo Hu·Hang Zhang·Yi Sun·Oleg V. Misochko·Kazutaka G. Nakamura
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Abstract

The coupling between longitudinal optical (LO) phonons and plasmons plays a fundamental role in determining the performance of doped semiconductor devices. In this work, we report a comparative investigation into the dependence of the coupling on temperature and doping in n- and p-type GaAs by using ultrafast optical phonon spectroscopy. A suppression of coherent oscillations has been observed in p-type GaAs at lower temperature, strikingly different from n-type GaAs and other materials in which coherent oscillations are strongly enhanced by cooling. We attribute this unexpected observation to a cooling-induced elongation of the depth of the depletion layer which effectively increases the screening time of surface field due to a slow diffusion of photoexcited carriers in p-type GaAs. Such an increase breaks the requirement for the generation of coherent LO phonons and, in turn, LO phonon-plasmon coupled modes because of their delayed formation in time.

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Jianbo Hu, Hang Zhang, Yi Sun, Oleg V. Misochko, Kazutaka G. Nakamura. 2018-04-14. Temperature effect on the coupling between coherent longitudinal phonons and plasmons in n- and p-type GaAs. https://doi.org/10.1103/physrevb.97.165307

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