The indices of refraction of molecular-beam epitaxy-grown BexZn1−xTe ternary alloys
We have used a combination of prism-coupling, reflectivity, and ellipsometric techniques to investigate the indices of refraction, n, of a series of BexZn1−xTe thin films grown on InP substrates. After determining the concentrations of each of the BexZn1−xTe alloys using x-ray diffraction measurements, we measured their n at discrete wavelengths using a prism-coupler setup. In addition, we used reflectivity measurements to complement the prism-coupler data and arrive at the dispersion relations of n for the BexZn1−xTe alloys below their fundamental energy gaps. We then employed a rotating analyzer-spectroscopic ellipsometer to measure the complex reflection ratio for each of the films at angles of incidence of 65°, 70°, and 75°. By using the n values obtained from both the prism-coupler and the reflection-spectroscopy techniques to guide the ellipsometric analysis, we were able to obtain accurate results for the dispersion of n for the BexZn1−xTe alloys, not only below their fundamental energy gaps, but also above their energy gaps (up to 6.5 eV) using these three complementary techniques.
Peiris, F.C., Buckley, M.R., Maksimov, O. et al. Journal of Elec Materi (2003) 32: 742. doi:10.1007/s11664-003-0063-9.
Journal of Electronic Materials