Infrared absorption and Raman spectroscopy studies of InSbBi layers grown by liquid phase epitaxy

We report on the results of optical absorption and Raman spectroscopy measurements on InSbBi layers grown by liquid phase technique. A maximum Bi content of 0.4 at.%, as measured by energy dispersive X-ray (EDX) technique, is used in the experiments. Optical absorption measurements made on the samples indicate a room temperature energy band gap reduction up to about 6 meV with respect to undoped InSb layers grown by the same technique. Bi content calculated from this band gap reduction agrees with that obtained from EDX. A weak peak obtained at 152 cm−1 in the Raman spectrum of the material is identified with the longitudinal optical phonon mode of InBi. Further a mode at 140 cm−1 is observed due to isolated Bi atoms at the interstitial sites.