Raman scattering studies of dilute InP1−xBix alloys reveal unusually strong oscillator strength for Bi-induced modes
Room-temperature Raman scattering studies of new InP1−xBix alloys grown by molecular beam epitaxy are reported. Two new Bi-induced vibrations observed at 149 and 171 cm−1 are assigned to InBi-like TO and LO phonon modes, respectively, and exhibit an unusually strong intensity for the dilute regime. Two additional modes at 311 and 337 cm−1 are resolved as well with unknown origins. The Raman intensities of the InBi-like TO and LO bands, as well as the new mode at 337 cm−1, exhibit strong and linear dependence on the Bi concentration for the composition range studied, 0.003 ≤ x ≤ 0.023. This correlation may serve as a fast and convenient means of characterizing bismuth composition not only in the ternary alloy InP1−xBix but also in the quaternaries such as In1−yGayP1−xBix and In1−yAlyP1−xBix.