Abstract
•The buffer layer thickness governs the Bi incorporation in the subsequent layer.•The buffer layer surface feature governs the homogeneity of the InAsBi layer surface.•The shrinkage of the critical points energies confirms optically the Bi incorporation.
Different InAsBi/buffer-InAs/GaAs(100) and InAs/GaAs(100) heterostructures have been grown by metal-organic chemical vapor deposition at 375°C. The epitaxy was monitored, in the visible – near-infrared domain, by employing the reflectance spectroscopy (RS) technique. Bismuth (Bi) incorporation has been quantitatively and qualitatively discussed in the light of optical measurement performed by ex situ spectroscopic ellipsometry and in situ RS measurements; It induced a narrowing of the E1 and E1+Δ1 critical points in comparison to those of InAs. The shrinkage-rate was of 4.5meV/%Bi and 7.8meV/%Bi, respectively for E1 and E1+Δ1. The effect of various buffer layer thicknesses on physical, epitaxial, structural, and morphological modifications of InAs1-xBix layers have been explored using high-resolution X-ray diffraction and atomic force microscopy. We found that the InAs buffer layer surface structure and thickness dominate the structural features and the uniformity of the InAsBi films. The optical parametric quantities such as the refractive index and the extinction coefficient are determined in comparison with available experimental and theoretical data. The value of the bismuth composition obtained from the analysis of in situ reflectance data agrees very well with that given by HRXRD analysis. The presented results contribute to a better understanding of Bi-containing III–V alloys growth mechanisms.