Analysis of the VIS–NIR spectral reflectance of Bi/GaAs structures grown by MOVPE and UHVE

• Bismuth films have been grown onto GaAs substrates by MOVPE and UHVE.
• Optical properties of Bi/GaAs were investigated using an SR technique.
• Bismuth optical constants were determined in the range 400–1700 nm.
• SR signals show a peak at 0.9 eV attributed to bismuth.

Bismuth films have been deposited onto (001) GaAs substrates by metal organic vapor phase epitaxy and ultra-high vacuum evaporation. The optical and morphological properties of the Bi/GaAs samples were investigated using spectral reflectance (SR) and atomic force microscopy. The real refractive index and the extinction coefficient of bismuth were determined in the wavelength range 400–1700 nm using theoretical analysis of in situ and ex situ SR measurements. Best simulations of SR data versus time and wavelength allow the decoupling of the effects on reflectivity of parameters such as bismuth film׳s thickness, roughness and temperature. In the near infrared domain, SR signals present a peak at around 0.9 eV which can be attributed to bismuth.