Raman scattering in In1−xGaxAsyP1−y quaternary alloys

Abstract

We report a resonant Raman scattering study of quaternary In1−xGaxAsyP1−y alloys which confirms the four-mode behavior of the alloy. The scattering amplitude shows resonance enhancement at the E1 edge of the alloy which diminishes with increasing value of x, corresponding to increasing compositional disorder. This disorder further manifests itself in broadening and line-shape asymmetry of the stronger LO-phonon lines.

Interfacial intermixing and arsenic incorporation in thin InP barriers embedded in In0.53Ga0.47As

“…These maxima arise from scattering by an InPlike and a GaP-like LO phonon mode, respectively, and are characteristic for ternary Ga͑AsP͒ or quaternary ͑InGa͒͑AsP͒. 8 When the nominal InP layer width is increased to 5 nm the InP LO phonon line emerges superimposed on the spectrum of ͑InGa͒͑AsP͒. From the Raman spectra shown in Fig.…”

“…This unintentional incorporation is due to memory effects in the MOCVD reactor, which are caused by deposits formed upstream in the reactor when growing ͑In-Ga͒As prior to InP. For In 1Ϫx Ga x As y P 1Ϫy lattice matched to InP (y/xϷ2.2), the composition dependence of the E 1 /E 1 ϩ⌬ 1 gap energy 10 and of the frequency of the InP-like LO phonon 8,11 is known. The quaternary barrier materials formed in the present heterostructures, however, are not necessarily lattice matched to InP, thus making a precise determination of the amount of As incorporated impossible.…”

Phonons in strained In1−xGaxAs/InP epilayers

“…[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Our polarized spectra are very similar to those reported by Pearsall et al 8 and Estrera et al, 18 except that the relative band intensities have changed because of the use of a quasibackscattering geometry in our case compared with the true backscattering geometry of Pearsall et al and Estrera et al In our scattering geometry for X(Y X)Y polarization, LO phonons are expected to dominate the spectrum, while for X(Y Z)Y polarization transverse optical ͑TO͒ modes are allowed. Because of the quasibackscattering geometry employed here, some mixing of TO modes into the LO mode spectrum can be expected.…”

Phonons inIn0.53Ga0.47As/IRowell1, Yu2, Lockwood3 et al. 2003Phys. Rev. B7000View full textAdd to dashboardCite

“…3,4 These techniques can also provide information on the atomic structure of the heterointerfaces and on confinement effects in very thin layers. 3,4 There have been many infrared [5][6][7][8][9][10][11][12][13][14][15][16][17][18] and Raman [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] investigations of the In 1Ϫx Ga x As alloy, principally in the form of strained ͑thin͒ or relaxed ͑thick͒ epilayers grown on GaAs or InP. However, there are wide differences among these investigations not only in the concentration dependence of the optical phonon frequencies but also in the number of modes observed and their origin ͑see, for example, Adachi 34 and Nash et al 35 ͒.…”