Electronic band structure of wurtzite GaP nanowires via temperature dependent resonance Raman spectroscopy

Abstract

Raman measurements are performed on defect-free wurzite GaP nanowires. Resonance Raman measurements are carried out over the excitation energy range between 2.19 and 2.71 eV.Resonances at 2.38 eV and 2.67 eV of the E 1 (LO) mode and at 2.67 eV of the A 1 (LO) are observed. The presence of these intensity resonances clearly demonstrates the existence of energy states with  9hh and  7V ( 7C ) symmetries of the valence (conduction) band and allows to measure WZ phase GaP band energies at the  point. In addition, we have investigated temperature dependent resonant Raman measurements, which allowed us to extrapolate the zero temperature values of  point energies, along with the crystal field and spin-orbit splitting energies. Above results provide a feedback for refining available theoretical calculations to derive the correct wurtzite III-V semiconductor band structure.

Forbidden Band‐Edge Excitons of Wurtzite‐GaP: A Theoretical View

“…These values together yield band positions of meV and meV below the VBM . The calculated band ordering is in agreement with experimental results …”

“…Higher‐energy transitions have been observed within the one‐phonon resonance Raman spectroscopy on wz ‐GaP NWs . Resonances have been found at 2.38 and 2.67 eV of the E 1 (LO) phonon mode and at 2.67 eV of the A 1 (LO) mode.…”

“…In the wurtzite geometry they may become direct semiconductors with the conduction band minimum at the point of the BZ . Indeed, wurtzite‐GaP but also wurtzite‐AlAs NWs have been grown and investigated . Moreover, Al x In 1− x P alloys have been grown in wurtzite geometry in core‐shell or unique NWs .…”

Optical study of the band structure of wurtzite GaP nanowires

“…Group theory predicts eight phonon normal modes at the C point: 2A 1 , 2E 1 , 2B 1 , 2E 2 for the WZ structure (see supplementary material, Fig. S4), 2,16,38 with one A 1 and one E 1 acoustic mode, while the remaining six modes are optical. Based on the expected shifts, the sharp peaks in Fig.…”

“…[10][11][12] Recently, the Auseeded growth of high purity WZ GaP nanowires via vaporliquid-solid (VLS) method was demonstrated, and the optical properties have been investigated. [13][14][15][16][17][18] Photoluminescence (PL) measurements on patterned arrays of WZ GaP wires showed optical emission at 2.09 eV with a short lifetime of $0.8 ns, indicating a direct band gap semiconductor. 13 Strain dependence of the optical emission 17 and estimation of the dielectric constant 18 provide additional information on this material system.…”