Publication Details

Steele, J. A., Lewis, R. A., Henini, M., Lemine, O. M. & Alkaoud, A. (2013). Raman scattering studies of strain effects in (100) and (311)B GaAs 1-xBix epitaxial layers. Journal of Applied Physics, 114 (19), 193516-1-193516-6.


We report room-temperature Raman studies of strained (100) and (311)B GaAs1-xBix epitaxial layers for x ≤ 0.039. The Raman spectra exhibit a two-mode behavior, as well as disorder-activated GaAs-like phonons. The experimental results show that the GaAs-like LO(Γ) mode experiences a strong composition-dependent redshift as a result of alloying. The peak frequency decreases linearly from the value for pure GaAs (∼293 cm-1) with the alloyed Bi fraction x and the introduced in-plane lattice strain ε, by Δ ω LO = Δ ω alloy-Δ ω strain. X-ray diffraction measurements are used to determine x and ε allowing Δ ω alloy to be decoupled and is estimated to be-12(±4) cm-1/x for (100) GaAs1- xBix. Δ ω LO is measured to be roughly double for samples grown on (311)B-oriented substrates to that of (100) GaAs. This large difference in redshift is accounted for by examining the Bi induced strain, effects from alloying, and defects formed during high-index (311)B crystal growth.

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