Raman line-shape analysis of random and spontaneously orderedGaInP2alloy

Abstract

We have measured the temperature dependence of the Raman frequency and linewidth of the GaPlike LO phonon of random and spontaneously ordered GaInP2 alloys. The width of the asymmetric Raman band is strongly influenced by disorder and the anharmonicity of the lattice. The half-width towards the high-energy side of the Raman band of the GaP-like phonon is independent of temperature, while the half-width on the low-energy side does depend on temperature. Though no obvious differences are observed in the temperature dependence of the Raman spectra of the random and the ordered alloys, the GaP-like Raman band of the ordered samples narrows for incident photon energies near the fundamental gap of the alloy. We attribute the narrowing of the Raman band to the inhomogeneities in the material caused by the existence of a statistical distribution of partially ordered domains with different order parameters g. From the observed width of the dispersion of the Raman linewidth as a function of incident photon energies under resonance conditions, it is concluded that samples grown at higher temperatures possess a narrower distribution of domains.

Infrared dielectric function and phonon modes of highly disordered(AlxGa1−xHofmann1, Leibiger2, Gottschalch3 et al. 2001Phys. Rev. B322230View full textAdd to dashboardCite

“…A feasible alternative to access strain, composition, and ordering information is to study the phonon mode spectra of the solid solutions because chemical ͑composition͒, structural ͑strain͒, and configuration ͑ordering͒ effects influence the short-range force constants as well as the long-range electrostatic fields. 17 FIR-transmission 18 and -reflection 19,20 and Raman scattering [21][22][23][24][25][26][27][28][29][30][31][32][33] ͑RS͒ spectroscopy were employed to study ordering-induced changes in the phonon spectrum of Ga 0.52 In 0.48 P, whereas no reports seem to exist for solutions with xϾ0. CuPt ordering induces additional modes in the acoustic region at 60 cm Ϫ1 and 205 cm Ϫ1 , which were identified as L-to-⌫ folded acoustic phonons.…”

A-site strontium doping effects on structure, magnetic, and photovoltaic properties of (Bi1−Sr )FeO3− multiferroic ceramics

“…Oxygen motions strongly dominate in Raman modes above 260 cm À 1 . The four lowest and strongest Raman vibrations can be attributed to the E(1) mode near 70 cm À 1 , E(LO2) mode near 130 cm À 1 , A 1 (LO1) mode near 160 cm À 1 , and A 1 (LO2) mode near 220 cm À 1 [35]. The atomic vibrations near 220 cm À 1 mainly originate from the A 1 tilt mode of the FeO 6 oxygen octahedra.…”

“…As shown in Fig. 1(c), the A-site Sr 2 þ doped (Bi 1 À x Sr x )FeO 3 À δ compounds exhibit broadened Raman spectra in the E(2) and A 1 (1) modes, which likely result from lattice anharmonicity and from disorder consisting of fluctuations in the cation-site occupancy [35]. The A 1 (1) and A 1 (2) peaks are suppressed likely due to the symmetric reduction of FeO 6 oxygen octahedra resulting from Sr 2 þ doping, which could disturb the local equilibrium energy.…”

“…The atomic vibrations near 220 cm À 1 mainly originate from the A 1 tilt mode of the FeO 6 oxygen octahedra. Two higher frequency Raman E(LO4) and E(LO8) modes appear respectively near 280 and 480 cm À 1 [35], which mainly associate with atomic vibrations between the A-site atom and oxygen. As shown in Fig.…”

“…Bi atoms participate mainly in the low-frequency modes below 170 cm À 1 and Fe atoms are involved in vibration modes in the region of 150-270 cm À 1 [35]. Oxygen motions strongly dominate in Raman modes above 260 cm À 1 .…”