Resonance Raman study of spontaneous ordering inGaInP2

Abstract

Raman and resonance Raman spectroscopic techniques have been utilized to study the phenomenon of spontaneous ordering in epitaxial Gao»Ino 48P grown on (001) GaAs substrates at difterent temperatures. Raman selection rules suggest larger deviations from cubic zinc-blende symmetry for samples exhibiting a greater degree of ordering. Raman excitation profiles show a redshift and broadening of the resonance peak as the samples become more ordered. In addition, the anisotropy of the absorption coefficients along the [110] and [110]crystallographic directions in the rhombohedral phase of the ordered material enables us to estimate the crystal-field splitting. Our results support the recently proposed microstructural model for ordering in these alloys.

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.…”

Optical properties of highly disordered InGaP by solid-source molecular beam epitaxy with a GaP decomposition source

“…Superperiodicity along the ordering direction lowers the symmetry from cubic ðT d Þ to rhombohedral ðC 3v Þ; and the resultant halving of the Brillouin zone leads to the folding of the conduction band at the L point of the original material to the zone center of the ordered alloy. The repulsion between the G 1 conduction band and the folded state results in band-gap reduction [15]. Therefore, the band gap of InGaP (generally measured by LT-PL) under a constant composition (In 0.483 Ga 0.517 P) can characterize the degree of atomic ordering, i.e., Z To date, band gap as high as 2.01070.007 eV of InGaP grown by LPE was considered as that of completely disordered [16].…”

NREL Photovoltaic Program. FY 1994 annual report, October 1, 1993--September 30, 1994

“…Microstructural studies were carried out by X-ray diffraction (XRD) and by transmission electron microscopy (TEM) using Philips 400, 420 and 430 instruments, two of which were equipped with EDAX energy-dispersive microchemical analysis instruments (EDS). Composition analyses were also carried out by secondary ion mass spectrometry (SIMS), and by EDS during scanning electron microscopy (SEM).…”