Summary: | Photoluminescence (PL) and Raman spectra of GaAs1-xBix
samples grown at different rates (0.09 to 0.5 µm/h) were
investigated. The PL peak wavelength initially redshifted with the increase of growth rate and reached the longest
wavelength (1158 nm) for sample grown at 0.23 µm/h. This is followed by PL peak wavelength blueshift for higher
growth rates. The Raman data show peaks at 162, 228, 270, and 295 cm-1 which can be attributed to GaAs like
phonons. GaBi like vibrational modes were also observed at 183 and 213 cm-1. However, the intensity of Bi induced
phonons is significantly weaker compared to GaAs due to low concentration of Bi compared to As and thin GaAs1-xBix
epilayer. The PL data and GaAs transverse optical (TO) to longitudinal optical (LO) phonons intensity ratio indicate
that Bi concentration is highly dependent on the growth rate and the highest Bi concentration was obtained by sample
grown at 0.23 µm/h. It is found that the full-width-at-half-maximum (FWHM) of GaAs LO mode increases significantly
for samples grown at high growth rates suggesting crystal quality degradation due to lack of surfactant effects.
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