Non-resonant Raman scattering of wurtzite GaAs and InP nanowires

• It is now possible to synthesize the wurtzite crystal phase of most III-V semiconductors in the form of nanowires. This sparks interest for fundamental research and adds extra degrees of freedom for designing novel devices. However, the understanding of many properties, such as phonon dispersion, of these wurtzite semiconductors is not yet complete, despite the extensive number of studies published. The E2 L and E2 H phonon modes exist in the wurtzite crystal phase only (not in zinc blende) where the E2 H mode has been already experimentally observed in Ga and In arsenides and phosphides, while the E2 L mode has been observed in GaP, but not in GaAs or InP. In order to determine the energy of E2 L in wurtzite GaAs and InP, we performed Raman scattering measurements on wurtzite GaAs and InP nanowires. We found clear evidence of the E2 L phonon mode at 64 cm−1 and 54 cm−1, respectively. Polarization-dependent experiments revealed similar selection rules for both the E2 L and the E2 H phonon modes (as expected) where the intensity peaked with excitation and detection polarization being perpendicular to the [0001] crystallographic direction. We further find that the splitting between the E1(TO) and A1(TO) modes is around 2 cm−1 in wurtzite GaAs and below 1 cm−1 in wurtzite InP. We believe these results will be useful for a better understanding of phonons in wurtzite crystal phase of III-V semiconductors as well as for testing and improving phonon dispersion calculations.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Nanoteknik -- Nanoteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Nano-technology -- Nano-technology (hsv//eng)

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

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