Resonant Raman scattering in hexagonal GaN

Abstract

We performed resonant Raman scattering in hexagonal GaN using discrete laser lines in the violet and UV spectral range for optical excitation. To tune the energetic position of the fundamental gap E0 of GaN relative to the exciting photon energy the sample temperature was varied between 77 and 870 K. Analyzing both Stokes and anti-Stokes Raman spectra, the resonance profiles for Fröhlich-induced one-E1(LO) and two-E1(LO) phonon scattering could be deduced, covering the energy range from 0.5 eV below the E0 gap up to the gap energy. The strength of deformation-potential scattering by the A1(TO) mode was used as an internal reference. For excitation slightly above the E0 gap energy E1(LO) multiphonon scattering up to the fourth order was observed, which reflects the stronger polarity of the Ga-N bond as compared to conventional III-V semiconductors.

Raman characterization of Ar+ ion‐implanted GaN

“…14 Second, the GaN material is Raman resonant at this excitation wavelength, giving far better sensitivity when a very thin material layer has to be probed. 15 Third, the energy of the exciting radiation is far larger than the GaN gap energy, allowing photoluminescence (PL) measurements to be made. All the measurements were performed at Jobin Yvon (Villeneuve d'Ascq, France) using a UV LABRAM Raman microspectrometer.…”

A Raman spectroscopy study of InN

“…The E 2 phonon is commonly not strongly affected by resonance excitation conditions since it is a non-polar phonon [17]. Comparison with resonant Raman scattering studies on GaN [17] suggests that resonant Raman scattering can be achieved in III-nitrides using excitation wavelengths within 200-300 meV of a critical point of the band structure. This result therefore indicates the presence of a critical point within about 200-300 meV of 1.49 eV in the InN band structure.…”

Raman scattering properties of GaN thin films grown on sapphire under visible and ultraviolet excitation

“…13 Further studies have also been carried out for GaN on the defect-induced RS in resonance with yellow luminescence, 14 subpicosecond time-resolved RS of the decay of LO phonons, 15 phonon dispersion and lattice dynamics, 16 quasi-LO and TO modes related to the wurtzite crystal structure, 17 ion implantation and annealing effects, 18 temperature dependence in a wide range of temperature, 78-870 K, 19 and phase-separated quantum dot structures. 20 Resonant Raman scattering (RRS), as a useful technique to gain an insight into the basic physical properties of materials, has been applied to hexagonal GaN, 21 InGaN-GaN 22 and GaN-AlGaN 23 quantum wells. Multiple LO phonon modes can be directly observed via 325 nm excitation at room temperature using a sensitive UV micro-Raman system.…”