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      https://www.ias.ac.in/article/fulltext/pram/035/02/0167-0176

    • Keywords

       

      Pressure-tuning; resonance Raman scattering; semiconductors

    • Abstract

       

      Hydrostatic pressure has been used to tune in resonance Raman scattering (RRS) in bulk GaAs. Using a diamond anvil cell, both the photoluminescence peak (PL) and the 2 LO and LO-phonon Raman scattered intensities have been monitored, to establish RRS conditions. When theE0 gap of GaAs matchesħωS orħωL, the 2 LO and LO-phonon intensity, respectively, exhibit resonance Raman scattering maxima, at pressures determined byħωL. With 647.1 nm radiation (ħωL = 1.916 eV), a sharp and narrow resonance peak at 3.75 GPa is observed for the 2 LO-phonon. At this pressure the 2 LO-phonon goes through its maximum intensity, and falls right on top of the PL peak, revealing thatħωS(2 LO) =E0. This is the condition for “outgoing” resonance. Experiments with other excitation energies (ħωL) show, that the 2 LO resonance peak-pressure moves to higher pressure with increasingħωL, and the shift follows precisely theE0 gap. Thus, the 2 LO RRS is an excellent probe to follow theE0 gap, far beyond the Γ-X cross-over point. A brief discussion of the theoretical expression for resonance Raman cross section is given, and from this the possibility of a double resonance condition for the observed 2 LO resonance is suggested. The LO-phonon resonance occurs at a pressure whenħωLE0, but the pressure-induced transparency of the GaAs masks the true resonance profile.

    • Author Affiliations

       

      A Jayaraman1 G A Kourouklis1 2 R People1 S K Sputz1 L Pfeiffer1

      1. AT&T Bell Laboratories, 600 Mountain Avenue, Murray Hill, NJ - 07974, USA
      2. School of Technology, Physics Division, Aristotle University of Thessaloniki, Thessaloniki, Greece
    • Dates

       
  • Pramana – Journal of Physics | News

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