Characterization of GaAs(1-x) Bi(x) Epilayers by Raman Scattering and X-ray Diffraction

For the first time, the Raman spectra of GaAs1-xBix, mixed crystal layers have been analysed at different temperatures in dependence on the molar fraction x. A two-mode behavior well-known from other ternary III-V single crystals have been observed and the GaBi-related 1LO phonon-like mode identified at about 190 cm-1 (77k) and 184 cm-1 (300K). A strong first order mode showing a pronounced temperature dependence has been interpreted as GaAs-related coupled 1LO-phonon-plasmon mode L. Nevertheless, a better understanding of the Raman spectra of the GaAs1-xBix system, in particular of modes found between the main phonon branches, is expected from the comparison with Raman results obtained analogously on InAs1-xBix epilayers. Both the weak second order phonon spectra and the X-ray rocking curves indicate that it is possible to grow layers of a good crystal quality ba MOVPE.