Temperature dependence of the InP(001) bulk and surface dielectric function

The bulk dielectric function, the surface reflectance anisotropy, and the surface dielectric anisotropy of InP(001) were determined from room temperature up to 875 K. Measurements were performed in-situ on as-grown samples in both a metal-organic vapour phase epitaxy and a chemical beam epitaxy (CBE) system using a rotating analyser type ellipsometer (SE) and a reflectance anisotropy spectrometer (RAS). The temperature dependence of the bulk critical points was deduced by performing a direct line shape analysis of the SE spectra. A high-temperature bulk dielectric function database for optical in-situ studies was established by applying a combined cubic spline/harmonic oscillator interpolation scheme to the measured data. Three InP(001) surface reconstructions were found by reflection high-energy electron diffraction (RHEED) measurements in the CBE system: (2 x 1) and c(4 x 4) under phosphorus-rich conditions and a (2 x 4) reconstruction under reduced phosphorus supply. Characteristic RAS spectra are assigned to these reconstructions. The temperature shift of the main features of the surface dielectric anisotropy spectra are compared to those of the bulk critical points.